TUNNEL LINING.pdf

Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy.A single copy of this document is licensed to URS On 04/03/2015 This is an uncontrolled copy. Ensure use of the most current version of the document by searching the Construction Information Service. TRANSPORT and R O A D RESEARCH L A B O R A T O R Y Department o f the ~ n v i r o n m e n t Department o f Transport Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. SUPPLEMENTARY REPORT 335 A REVIEW OF T U N N E L L I N I N G PRACTICE I N T H E U N I T E D K I N G D O M by R N Craig and A M M u i r Wood (Sir William Halcrow and Partners) The work described in this Report was sponsored by t h e T R R L A n y views expressed in this Report are n o t necessarily those o f the Transport and Road Research Laboratory o r o f any other division of either the Department o f the Environment o r the Department o f Transport Prepared f o r the Tunnels Division Structures Department Transport and Road Research Laboratory Crowthorne, Berkshire 1978 Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. CONTENTS Abstract 1. Introduction 2. Investigation methods Purpose and methods of lining tunnels 3. 3.1 General 3.2 Market for tunnel linings (1970-76) 3.3 Previous forms of tunnel linings 3.3.1 Timber 3.3.2 Brickwork 3.3.3 Masonry Cast iron and steel tunnel linings 4. 4.1 Cast iron tunnel linings Bolted grey iron tunnel linings 4.1.1 Bolted spheroidal graphite iron tunnel linings 4.1.2 Expanded grey iron tunnel linings 4.1.3 Expanded spheroidal graphite iron tunnel linings 4.1.4 4.2 Steel tunnel linings 4.2.1 Bolted steel tunnel linings 4.2.2 Expanded steel tunnel linings 4.2.3 Liner plates 5. Precast concrete tunnel linings 5.1 Moulds 5.2 Steel reinforcement 5.3 Joints 5.3.1 Plane or helical joints 5.3:2 ~ o n c a v e / c o n v e xand convex/convex joints 5.3.3 Tongue and groove joints 5.4 Bolted and dowelled tunnel linings 5.5 Expanded concrete tunnel linings 5.6 Grouted smooth bore concrete tunnel linings 5.7 Expanded grouted concrete tunnel linings 5 . 8 Pipe jacking with concrete pipes Cast in-situ concrete tunnel linings and temporary ground support 6. 6.1 Cast in-situ concrete tunnel linings 6.2 Rock bolting 6.3 Sprayed concrete tunnel linings 6.4 Temporary arch and lagging supports Instrumentation, monitoring, research and development 7. 7.1 General 7.2 Deformation of tunnel linings t s porewater pressure changes 7.3 Sub-surface n ~ o v e n ~ e nand Horizontal sub-surface movements transvers to tunnels 7.3.1 Horizontal movements parallel to the centre line of tunnels 7.3.2 7.3.3 7.3.4 Vertical ground movements Porewater pressure changes Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Ownership of the Transport Research Laboratory was transferred from the Department of Transport to a subsidiary of the Transport Research Foundation on 1'' April 1996. This report has been reproduced by permission of the Controller of HMSO. Extracts from the text may be reproduced, except for commercial purposes, provided the source is acknowledged. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. 7.4 Surface settlement Development of settlement profile and trough 7.4.1 7.4.2 Extent of settlement Discussion on ground movements and settlement 7.4.3 7.4.4 Settlement above multiple tunnels Settlement above tunnels constructed using pipe jacking methods 7.4.5 7.5 Stresses and hoop loads in linings 7.6 Recent instrumentation and monitoring of tunnels 7.7 Research 7.8 Development 8. Design 8.1 Designmethods 8.1.1 Soft ground tunnels 8.1.2 Rock tunnels 8.2 Joints in linings 8.3 Openings in preformed linings 8.4 Linings in mining areas 9. Waterproofing 9.1 Grouting 9.2 Lead caulking 9.3 Cement based caulking compounds 9.4 Flexible caulking compounds 9.5 Sealing strips 9.6 Grummets 10. Tunnel construction 10.1 Rates of Progress 10.2 Suggested tunnel lining methods 10.2.1 Bolted cast iron linings 10.2.2 Expanded cast iron linings 10.2.3 Bolted concrete linings 10.2.4 Grouted smooth bore concrete linings 10.2.5 Expanded concrete linings 10.2.6 Expanded grouted concrete linings 10.2.7 Steel liner plate linings 10.2.8 Steel circular membranes 10.2.9 Bolted and expanded steel linings 10.2.10 Cast in-situ concrete linings 10.2.1 1 Sprayed concrete or gunite linings 10.2.12 Rock bolting 10.2.13 Pipe jacking 10.3 Special ground conditions 10.3.1 Aggressive ground conditions 10.3.2 Mining areas 11. Costs 11.1 Unit cost of linings 11.1.1 Precast concrete linings 11.1.2 Cast iron linings 1 1.1.3 Secondary linings ' Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. 12. Maintenance 12.1 Road tunnels 12.2 Railway tunnels 12.3 Small diameter tunnels 13. Recommendations 13.1 Standardisation 13.2 Specifications 13.3 Developinent of linings 13.4 Waterproofing 13.5 Instrumentation, monitoring and research Acknowledgenlents 14. Appendix 1 List of organisations consulted 15. Appendix 2 Primary and secondary linings - General 15.1 Tunnel lining demand, 1970-76 15.1.1 Collection of data 15.1.2 Total length of tunnels constructed 15 .I .3 T o t a l excavated volume of tunnels constructed 15.1.4 Average external diameters of tunnels 15.1.5 Tunnelling in 1976-1980 15.1.6 Tunnelusage 15.2 Secondary linings 15.2.1 Brick lining 15.2.2 Cast in-situ concrete linings 15.2.3 Infill panels 15.2.4 Thin cement mortar linings 15.2.5 Sprayedmortarorgunitelinings 15.2.6 Steel linings 15.2.7 Glass reinforced linings 15.2.8 Other forms of secondary linings 16. 15.3 Developments overseas 15.3.1 Concrete linings 15.3.2 Cast iron linings 15.3.3 Steel linings 15.3.4 Other forms of lining Appendix 3 Cast iron and steel tunnel linings 16.1 Grey iron 16.2 Spheroidal graphite iron 16.3 Manufacture of cast iron linings 16.4 Steel linings 16.5 Bolted grey iron linings 16.6 Bolted spheroidal graphite iron 16.7 Bolted steel linings 16.8 Expanded grey iron lining 1 6.8.1 Articulated grey iron lining 16.8.2 Expanded bolted grey iron lining 16.9 Expanded steel linings 16.10Steel liner plates 16.10.1 Armco liner plates 16.10.2 Com~nercialHydraulics liner plates Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. 17. Appendix 4 Precast concrete tunnel linings 17.1 General 17.2 Manufacture 17.3 Moulds 17.4 Reinforcement 17.5 Joints 17.6 Bolted and dowelled concrete linings 17.6.1 LTE - Central Line extension 17.6.2 Deep tunnel air raid shelters in London 17.6.3 Defence installation - Dorset Coast 17.6.4 Standard bolted concrete linings 17.7 Expanded concrete linings 17.7.1 Don-Seg lining 17.7.2 Wedge Block lining 17.7.3 Greenwood to Potters Bar tunnels 17.7.4 LTE running tunnels 17.7.5 Heathrow Cargo tunnel 17.7.6 Collins lining 17.8 Grouted smooth bore tunnel lining 17.8.1 McAlpine lining 17.8.2 Spun Concrete Flexilok lining 17.8.3 Spun Concrete Extra Flex lining 17.8.4 Charcon Tunnels Rapid lining 17.8.5 Charcon Tunnels Universal lining 17.8.6 Rees Mini tunnel 17.8.7 Mersey Kingsway and Dartford Duplication tunnels 17.9 Expanded grouted concrete tunnel linings 18. Appendix 5 Cast in-situ concrete tunnel linings and temprary ground support 18.1 Cast in-situ concrete tunnel linings 18.1.1 Roadtunnels 18.1.2 Railway tunnels 18.1.3 Water tunnels 18.1.4 Sewer tunnels 18.2 Rock bolting 18.2.1 Mechanical anchored bolts 18.2.2 Resin anchored bolts 18.2.3 Other forms of anchor 18.3 Sprayed concrete tunnel linings 18.4 Temporary arch and lagging supports 18.4.1 Steel arches 18.4.2 Bernold system 19. Appendix 6 Instrumentation, monitoring research and development 19.1 Instrumentation and monitoring 19.1.1 LTE Central Line extension to Ilford (1942) 19.1.2 MWB Ashford Common tunnel (1952) 19.1.3 LTE underground tunnels (1952-5 6) 19.1.4 River Clyde water tunnel (1953-55) 19.1.5 Shell building 1957 19.1.6 MWB tunnels (1955-75) 1 8 LTE .1.1. URS Infrastructure.1 . 20.22 NWA Tyneside sewerage scheme .2 Morgan's ~ e t h o d ~ ' 20.6 Temporary design conditions 20.9 LTE Victoria Line (1960-1968) 19.Tyne Syphon (1974) 19.1.1.24 NWA Kielder scheme (1974) 19.Fleet Line at New Cross (1973) 19.1.Heathrow cargo tunnel (1968) 19.1.1.23 Kings Lynn mini tunnel (1974) 19.I 6 Cleveland Potash: Boulby Shaft (1973-1975) 19.4 Schulze and Duddeck Methods 20.13 Ely-Ouse water tunnel (1969-1973) 19.10 Elephant and Castle shopping centre (1963-1965) 19.1 5 CEGB Severn-Wye cable tunnel (1972-1973) 19.8 CEGB.1 Bull's Method 20.Fleet Line at Regents Park (1973-1974) 19.1 1 BAA .Hebburn contract (1973-1974) 19.19 LTE .7 Clyde vehicular tunnel (1954-1961) 19.7 Terzaghi's Method References 0 CROWN COPYRIGHT I978 Extracts from the text may be reproduced except for commercial pulposes provided the source is acknowledged . Sizewell Power Station cooling water tunnels (1962-1963) 19.1.Willington Gut (1974-1975) 19.3 Development Appendix 7 Design methods 20.Licensed copy from CIS: URS.1.1.28 Tunnels crossing at right angles or on the skew 19.1 7 BR Liverpool Loop-Moorfields Station (1 973-1975) 19. Uncontrolled Copy.1.29 Settlement at the surface 19.1. 04/03/2015.14 LTE Fleet Line at Green Park (1972-1973) 19.1.1.1.1.1.25 TRRL Chinnor trials (1974) 19i1.12 Mersey Kingsway tunnels 2A and 2B (1968-1972) 19.1. 19.3 Muir Wood's Method 20.2 Research 19.20 NWA Tyneside sewerage scheme .1.5 Peck's Method 20.27 Channel Tunnel Stage 2 (1974-1975) 19.1.1. 2 1.26 Warrington sewer (1975-1976) 19.21 NWA Tyneside sewerage scheme . This Report is divided into two parts with details of tunnel linings. Uncontrolled Copy. After discussion with Sir William Halcrow and Partners. The several methods of lining are discussed in Chapters 3 . are seldom unanimous on the best lining to use in given circumstances. Methods of waterproofing tunnels. In addition. recohmended that a review be carried out of tunnel lining . 04/03/2015. the senior author was seconded to the Transport and Road Research Laboratory t o carry out the survey. 1. 3 . in 1970 1. ABSTRACT This Report outlines the several methods used in the United Kingdom for lining tunnels and gives brief details of some of the more recent tunnels constructed with each form of lining.S. Tumellers. The ground conditions in which each lining has been constructed are given together with tunnel usage. Consulting Engineers. 4.A.A REVIEW OF TUNNEL LINING PRACTICE I N T H E U N I T E D KINGDOM Licensed copy from CIS: URS. INTRODUCTION Following the Organisation for Economic Co-operation and Development (OECD) Advisory Conference on Tunnelling held in Washington. including brief details of some o f t h e more recent tunnels. The approximate annual length and volume of tunnels constructed for the period 1970-76 are given. broken down into different types of lining and tunnel usage. However. 4 and 5. in the Appendices.theTransportand Road Research Laboratory's Research Committee on Tunnels. in some instances the choice of lining may not necessarily have been that most suited t o the ground conditions.Om diameter t o the largest road tunnels. the ground conditions likely to be encountered may not have been accurately known or may be so variable as to require a highly tolerant scheme. weak rock or shattered or heavily jointed rock. use of secondary linings and cost data are included. The Report is aimed to give comprehensive information on tunnelling practice and research on tunnel linings in the United Kingdom which will be useful not only t o those who have a wide knowledge but also to those with little or no knowledge of tunnelling who may be considering the use of tunnels for future schemes. The different methods available for lining tunnels are discussed taking into account the tunnel usage and the ground conditions. URS Infrastructure. like most groups of engineers.s and 6 with additional data in Appendices 2. There is a predominant use in the United Kingdom of preformed linings since the localities for much o f the recent tunnelling are found in soft ground.practice in the United Kingdom. There is great skill in knowing when t o specify the .2 on the advice of the Panel on Tunnel Linings. The instrumentation of tunnel linings and of ground movements during the construction of tunnels have been examined and the design methods are discussed. design and recommendations in the main text which is supplemented with more detailed data. It covers the whole field of tunnels from the 1 . research. U. Recommendations are given for research and development of tunnel linings. 04/03/2015. URS Infrastructure. to cover both extremes of the tolerant and the specific types of lining. take into account tunnel usage and ground conditions and have therefore.Licensed copy from CIS: URS. . however. When making suggestions for future research and development. given in Chapter 10. This Report attempts t o distinguish between fact and opinion. Uncontrolled Copy. The market for tunnel linings in the United Kingdom is briefly discussed in Chapter 3 with more detailed information in Appendix 2 . t o some extent. pointing t o the factors which should be considered in selecting a tunnelling system. types of linings and methods which have been well tried and proven over the last 2 0 to 100 years and when to pioneer the new tunnel linings and/or construction methods which have greatly contributed to reduce the overall cost o f tunnelling. some new ideas have been put forward as a basis for discussion. I n each instance there will be a choice and the final decision must be an engineering judgement after weighing up the technical and economic considerations. The recommendations for the methods of lining tunnels. where statistics are given of the approxiinate annual length and volume of tunnels constructed. broken down into the several forms of tunnel linings and tunnel usage. research organisations and universities working on tunnelling problems. b u t this has to be seen in the knowledge that a wider investigation would entail diminishing returns.Licensed copy from CIS: URS. At the outset of the survey. manufacturers of linings. A list of organisations was drawn up consisting of the larger local authorities. assistance and free discussion with disclosure of much valuable and sometimes confidential material. It was clearly impossible to cover more than a small percentage of those organisations concerned in tunnelling. The authors and the Transport and Road Research Laboratory are very grateful to all these organisations for their co-operation in this survey. In particular. a list of which is given in Appendix 1. many on several occasions. INVESTIGATION METHODS The survey has been carried out by reference to published literature on design and construction of recent tunnels and by discussions with interested and experienced organisations. In almost every case there was good co-operation. from this material and with the consent of the organisations concerned. the importance o f personal discussions and visits t o tunnelling sites was seen as far more fruitful than the circulation of questionnaires. it has been possible to draw up the histograms and graphs of lengths of tunnels constructed and of related costs. 2. . shields and waterproofing materials. a selection of the larger tunnelling consulting engineers and contractors. 04/03/2015. URS Infrastructure. Uncontrolled Copy. Some fifty such organisations were visited. for underground railways and associated tunnels and for the larger sewer and water tunnels. for sewers. sandstones and medium strength Carboniferous coal measures. URS Infrastructure. PURPOSE AND METHODS OF LINING TUNNELS 3. up t o 3 m internal diameter. 3 ni to 6 m internal diameter. water and cable tunnels. Very strong and extremely strong rock above 100 The hard Carboniferous and older rocks. the discontinuity characteristics and the amount of A method commonly used for indicating the intensity of ( . Uncontrolled Copy. Strong rock 5 0 to 100 Many Triassic and Permian rock formations. The size of tunnels constructed in the United Kingdom may be classed in three categories. which may be classified under the headings given in Table I . Cretaceous and Jurassic stiff fissured clays. silts and clays and boulder clay. 6 m upwards internal diameter.1 General Licensed copy from CIS: URS. is the proportion of a borehole core that discontinuities is that of Rock Quality Designation R Q D ) ~which eath her in^. for convenience for tunnelling methods and techniques. c) Large diameter tunnels. TABLE 1 Ground classification Classification Compressive strength M N / ~ ~ Ground type - (a) Recent alluvium and glacial drift deposits including waterbearing sands. . gravels. b) Medium diameter tunnels. These tunnels are constructed through a large variety of ground types.^'^?^ * The Geologist would describe 'soft ground' as 'unconsolidated deposits' but this designation would be confusing in the engineering context. - (b) Eocene. Triassic (Keupar) Marl and Jurassic rock formations. for road and main line railway tunnels. predominantly in soft ground* or weak t o moderately strong rock.3. a) Small diameter tunnels. Soft ground This classification is based on the rock strengths and terminology given in the Geological Society Engineering Group. 04/03/2015. Cretaceous Chalk. The rock groupings have been reduced to three. Working Party Report 3 and on the new British Standards Institution draft code of practice on site investigations4 . the limestones and harder rocks. The classification of rock masses should also include the structure of the rock. underground chambers and larger tunnels associated with underground railways. Very weak to moderately strong rock up to 5 0 Low strength rocks including shales. only some of which require secondary linings. URS Infrastructure. All tunnels.lm. The secondary lining will provide a smooth bore finish to the tunnel and may be necessary to prevent erosion o f the primary lining or t o act as an anti-corrosion barrier. 04/03/2015. Rock classification by strength and discontinuity spacing has been used t o indicate preferred methods of excavation?*10 However.consists of intact lengths longer than O. This was later used t o classify the stronger rocks7 . where the ground is self supporting are lined with a "primary lining" which is designed to support the ground loads and t o sustain such deformations of the lining which may occur in the temporary conditions and for the design life of the structure. shotcrete and rock bolts are commonly used for temporary ground support. The primary lining should also exclude or control the ingress of water into the tunnel.1 m lengths is insensitive t o variations in rock quality when the mean discontinuity spacing is greater than 0. A secondary lining may also be used as a waterproof umbrella. The most severe stress conditions for many preformed linings may occur during handling of the segments or from thrust from the shield rams. for the design of tunnel support systems more complicated designations are necessary as discussed in Chapter 8. Three forms of lining may be used during the construction of a tunnel: a) Temporary ground support b) Primary lining c) Secondary lining In rock tunnels where the ground is not fully self supporting and where the primary lining is not erected or cast as the excavation proceeds. A 'secondary lining' may be required to convert the primary lining to a form suitable for the tunnel use. They advocated presenting rock quality information in terms of average fracture spacing or frequency.3 m. Secondary linings are briefly included in Appendix 2 in order that cost comparisons can be made concerning the different forms of primary linings. Uncontrolled Copy. Steel arches. Priest and Hudson 8 have shown that the conventional RQD based on 0. such as the bolted linings which are not usually designed to take full bending moments across the joints. as insulation or to provide an aesthetic finish. 1: a) a bolted grouted lining b) an expanded lining c) a smooth bore grouted lining d) a cast in-situ lining . a "temporary ground support" may be necessary t o support the ground until the primary lining is complete. as illustrated in Fig. Table 2 gives details of the types of primary lining in relation t o the usage of the tunnels and the need for a secondary lining.' Licensed copy from CIS: URS. The primary lining for a tunnel may be one of several forms of lining. Several forms of primary lining are commonly used ranging from the monolithic cast in-situ concrete linings to the flexible types of articulated linings which have a number of segments allowing the lining t o deform to reach an equilibrium state with the forces acting on the lining. except in sound unjointed rock. In between these extremes there are linings of different degrees of stiffness. which allows the line of contact to rotate from the designed position without overstressing the joint. This form of lining has been manufactured in concrete. After erection the void behind the lining is grouted or alternatively filled with pea gravel and then grouted. The segments are bolted together along the longitudinal flanges t o form rings and along the circumferential flanges for erection purposes and for continuity in the longitudinal direction. The lining is erected and bolted t o the previous ring and the void between the external periphery of the lining and the excavation filled with a grout or with pea gravel and grout. aesthetic lining required if not incorporated in primary lining The 'bolted' lining is made up of a number of segments cast with a skin or web curved to the radius of the tunnel with flanges along each of the four sides. The lining may be expanded in the crown or a t or near the axis level (see Section 5 . URS Infrastructure. waterproof.3). The 'expanded' lining is made up of a number of segments which are erected without bolts in the longitudinal joints and are expanded t o fit the profile of the excavation (see Fig. The 'smooth bore' lining is made u p of a number of solid segments with plane or articulated joints. 04/03/2015.'ordinary' segments. These linings have been manufactured only in concrete. The articulated joint may be of a convex/convex or concave/ convex profile. waterproof. a smaller 'key' segment and adjacent 'top' segments. Usage Bolted linings Smooth bore linings Sewer Smooth bore finish required Generally no secondary lining Water Smooth bore finish required Generally no secondary lining Cable Generally no secondary lining unless for waterproofing reasons Underground railways Generally no secondary lining unless for waterproofing or acoustic reasons High speed railways Smooth bore finish probably required Generally no secondary lining unless for waterproofing reasons Road and Pedestrian Passages Secondary. 5 ) . The linings are normally erected either on a former ring or with reinforcement in the joint (or in the centre of the ring) o r each ring may be bolted t o the previous ring. 1). cast iron and steel. . The present form of this lining is used with a tailless shield in self supporting ground in which a true circular profile can be cut. The longitudinal joints may be plane or articulated (see Section 5. Uncontrolled Copy. The rings are made up of three types of segments . cast iron and steel.TABLE 2 Need for secondary lining related t o type of tunnel usage Type of primary preformed lining Licensed copy from CIS: URS. This form of lining has been manufactured in concrete. aesthetic lining required Secondary. The plane joint gives a flat contact surface between segments while the articulated joint gives theoretically a line or point contact. .1 * 5.1 74 18 49 24 Includes the Mersey Kingsway 2B Tunnel 3.5 6. Licensed copy from CIS: URS.O 3. Uncontrolled Copy.2 Market for tunnel linings (1970-76) During the course of the latter part of the survey it was possible. to obtain data on the production and delivery of tunnel linings. These data represent the first compilation of such information in a comprehensive manner and should form a reliable datum for future tabulation and predictions.9 5. These statistics are included in Appendix 2 and a summary of the combined data is given in Table 3. In order t o obtain a realistic figure for the length of tunnels constructed the total number of rings of each diameter delivered t o the sites for each calendar year was abstracted from the records of each manufacturer.6 2. taking into account the type of tunnel usage and the ground conditions.The 'cast in-situ' lining is generally used in rock where only temporary ground support is required during the excavation for the tunnel.1 2. URS Infrastructure. The lining is then cast as a separate operation.1 68 67 71 71 75 88 80 27 24 20 13 15 5 15 46 28 58 49 53 72 48 32 42 21 14 16 5 33 3. TABLE 3 Tunnel statistics Year 1970 1971 1972 1973 1974 1975 1976 Length constructed Total volume of excavation Average external diameter km 100. s and 6 the type of primary linings used in the United Kingdom are briefly discussed with additional data in Appendices 3 . This is due mainly to the introduction of new materials and tunnelling techniques which have enabled the construction of tunnels t o be carried out at rates of progress many times those previously attained. or with cast in-situ concrete or left unlined were estimated from site data.000 m3 65 62 83 122 77 81 81 4. brickwork and masonry.1 3. In Chapters 4 . In Chapter 10 general recommendations are given on the types of lining to be used for particular tunnels. 3.3 8. 04/03/2015. 5O 6. These chapters give a general background to the individual linings with information on where and in what ground conditions they have been used. The lengths of tunnels lined with segments cast on site. with the co-operation of the lining manufacturers.6 . 4 and 5.8 3.3 Previous forms of tunnel linings Many of the tunnels in service today have been in use for up to 150 years and were constructed with forms of linings which have not been used for new tunnels for many years.2 Average * Percentage of total length Percentage of total volume sewer water sewer water m % % % % 3 . The three main forms of lining which fall into this category are timber.9 3. Many millions o f bricks were required for the longer tunnels. The use of timber headings. enlargements and the economic shape of the sewer. For sewers. In the United Kingdom where soft ground tunnelling predominates. over 1000 in number. Uncontrolled Copy. The thickness of the brickwork varied from tunnel t o tunnel b u t was normally between four and eight rings. The majority of these brick sewers are now about 100 years old and many of these may well require considerable repairs or replacement during the next two decades. breakups for enlargements and openings. For underground railways. Timber has a limited life except for pitch pine and elm in the fully saturated state. Apart from the use of brickwork as a secondary lining inside a precast concrete primary lining (see Section 15. There is little standardisation in the cross-section profile of these tunnels though they are usually a horseshoe shape. brickwork was often used for the cut and cover section and for tunnels and station walls constructed in headings. For deep tunnels. brickwork has been used for many hundreds of kilometres of tunnel and was the main form of lining for sewers constructed until the 1930's except for sections in difficult ground where cast iron linings were installed. for temporary ground support in timber headings o r at special locations such as junctions. Mersey Railway Tunnel and the Severn Railway Tunnel are beneath rivers. such that subsequently the clay softened and the invert support was lost often aided by inadequate or blocked drainage. 3. which was once common for small diameter pipes or cable ducts in built up areas has reduced during the last decade. This is mainly due to the introduction of new smaller-diameter tunnelling techniques. In poor ground. URS Infrastructure. For shallow and medium depth tunnels many faces were worked simultaneously t o speed construction. 1 0 m high and 120 rn long. States as a structural lining in-conjunction with an internal skin of brickwork or concrete.1 Timber: Timber is a traditional building material and has been used on a limited scale in the United Licensed copy from CIS: URS. on British Railways (BR) routes are brick lined and were constructed 75 to 125 years ago. supported by timber formwork in the crown. 04/03/2015. Great cost and effort was given to the quality and precision of the brickwork. The brickwork was built up or the in-situ concrete cast from the invert upwards until the whole section.2 Brickwork: Brickwork linings have been used for a considerable length of tunnel in the United Kingdom. The thickness of the brickwork varied from 2 rings of bricks for the smaller diameter sewers in clay to 4 rings for larger tunnels. The system of crown bars may be seen as a forerunner of the tunnel shield. The egg-shaped sewer is one such profile. very few brick-lined sewers have been constructed during the last 2 0 years. coupled with the increased cost of timber and of skilled workmen with the accon~panyingdecline in timbering skills. brick railway tunnels were often constructed without a structural invert. for example 36 million were used for the Kilsby Tunnel in the 1820's and 3 8 n~illionfor the Mersey Railway Tunnel in the 1880's. Brickwork has been used extensively for canal and river tunnels.13 For some tunnels the bricks were made in the vicinity of the construction and often from the excavated material.2). This method incorporated a bottom haulage heading which was constructed ahead of the main tunnel. Several of these old tunnels. The great majority of railway tunnels.3. A t o p heading was then excavated 3 m to 6 m ahead supported by crown bars extended from the section previously constructed. however. Economics dictate that timber is used today as a temporary ground support in conjunction with steel arches for rock tunnels. In stiff clays. Many of these tunnels were constructed using the 'English Method' of tunnelling. had been constructed.3. Brickwork has advantages for sewers in that the sectional profile may readily be altered t o suit junctions. a n d has normally t o be imported to this country. In deep road tunnels the use of brickwork has been confined to internal architectural finishes.3. the largest probably being those built for the deep level station on the Mersey Railway at Hamilton Square and James Street which are 15 m wide.13 The majority of railway tunnels are twin track tunnels with u p t o 100 metres of overburden. brickwork linings have seldom been built except for special sections at junction openings or overbridge passages. . followed b y the bottom half. timber has normally been used only as a temporary ground support until the final structural lining is constructed. such as the Thames (Wapping) Tunnel. additional thicknesses were often necessary. The enlargement for the top half of the tunnel was then excavated. Local stone was used in the interest of economy and was not always resistant to severe atmospheric conditions associated with steam driven engines.Licensed copy from CIS: URS. Disadvantages of brick tunnels include the large quantity of timber work and centering which is required and the consequent congestion at the face. Uncontrolled Copy. These tunnels which were replaced by the new Woodhead Tunnel have been relined and now carry Central Electricity Generating Board (CEGB) cables. most of these being water or railway tunnels. The repair of brickwork and masonry tunnels is briefly discussed in Chapter 12 on maintenance.3 Masonry: There are few tunnels in Britain lined with masonry. The old Woodhead Twin Tunnels provide an example where severe deterioration of the mortar in the joints between the stones resulted in falls during the last years of the railway life. precautions are necessary to avoid the thrust loads causing damage to the newly erected brickwork. The use of multiple faces compensated for this t o some degree by allowing the alternation of excavation and brickwork gangs between faces. 04/03/2015. . Progress was bound to be slow due to the delay in erecting the brickwork lining after the excavation and timbering for a length of tunnel. URS Infrastructure.3. For railway tunnels this form of lining was only economic when used in place of a thick brick lining where heavy loads were anticipated. Although brick linings have been used in conjunction with a shield. 3. the grouting of the void between the ground and the external surface of the lining is carried out after the shield has been shoved forward for the next ring.6 and 9. the San Paulo Metro.000 tonnes of spheroidal graphite iron were exported to South America. Thus in the larger diameter tunnels. Cast iron linings. Fig. and the early stages of the first Mersey Kingsway Road Tunnel. CAST IRON A N D STEEL TUNNEL LININGS Licensed copy from CIS: URS. 2 shows the annual production.500 tonnes). Uncontrolled Copy. have been competitive with the conventional grey iron linings. has seldom been used in the United Kingdom (see Sections 5.000 tonnes were cast at an annual production rate of approximately 45. rings of widths up t o 1. have been of the bolted type and have usually been used with a shield for long drives.1). with fewer circumferential bolts and thus reduced erection times. This lining was used in good cohesive ground in conjunction with a tailless shield and was later used for sections of the Victoria Line. the LTE Fleet Line (Stage l ) . is mainly adopted for special sections or for tunnels in waterbearing ground where a cast iron lining can be made more watertight than a concrete lining. Alternatively pea gravel may be injected in the void as the shield is shoved forward and the grouting carried out at a later date. The lining was erected without bolts in the longitudinal joints and with fewer bolts in the circumferential joints than for the conventional bolted lining. in tonnes. however. In the early 1960's an expanded form of grey iron lining was developed for the experimental tunnel for the London Transport Executive (LTE) Victoria Line. for which approximately 12. generally. The peak of production during the period 1963-67 is mainly due to the LTE Victoria Line. Cast iron linings have traditionally been manufactured from grey iron which derives its name from the grey crystalline appearance of its fractured structure on account of the presence of free flake graphite. When a shield is used in non-cohesive ground the lining is erected within the shield tail skin. Spheroidal graphite iron is more expensive than grey iron but.000 tonnes. which overlaps a short length of the previously erected ring. During the last decade successful experiments have been carried out with tunnel linings cast in spheroidal graphite iron which has a chemical composition similar t o grey iron except that the impurities of manganese. spheroidal graphite iron is likely to be more economical for most diameters of tunnels. thinner and wider sections can be designed which may be more economical. . sulphur and phosphorus are reduced. This latter method. During the last decade the use of this type of lining has reduced as a percentage of the total length of tunnel constructed. The flake graphite is changed to spheroidalgraphite by the addition of very small proportions of cerium or magnesium.2 m . for which 120.4. the Blackwall Road Tunnel (25. in good cohesive ground with long stand up time.000 tonnes) and the Tyne Road Tunnel (45. Cast iron linings have been used for a relatively small number of large projects which have been influenced in their timing by financial constraints. The smaller peak 1967-70 included the LTE Victoria Line extension to Brixton (37.000 tonnes). of cast iron segments in the United Kingdom for the period 1963-74 broken down into the weights of grey iron and spheroidal graphite iron used both in the United Kingdom and exported for use abroad 1 4. URS Infrastructure. on account of its higher tensile strength. 04/03/2015. short lengths of tunnel have been excavated and t h e lining erected by hand without a shield. the BR Liverpool Loop Railway. The bolted form of cast iron lining. The 197 1-74 peak included part of the lining for the second Mersey Kingsway Road Tunnel.now rarely used for tunnels in good ground apart from step plate junctions between tunnels. although. In the future. the Washington Metro and part of the lining for the early stages of the Dartford Duplication Road Tunnel. Steel has been used relatively little for primary tunnel linings in the United Kingdom mainly on account of its high cost. During the period an average of 10 per cent of the production was for export with a peak of over 35 per cent in 1973. The production of cast iron segments. The present capacity is between 20.000 tonnes of cast iron with variations depending upon the ratio of grey iron to spheroidal graphite iron. however. The majority of schemes using cast iron linings require a production of less than 45. the percentage by weight of cast iron segments was only 1.000 tonnes and a trough of 6.5 per cent of the total production. although a number of foundries will manufacture small quantities of special linings. The. Brief details of the types of cast iron and steel linings used in the United Kingdom are given in the following sections with further details including the characteristics and manufacture in Appendix 3. Its main use has been for special lengths of tunnel where the loads from the ground or from the shield have caused high bending moments or tensile stresses in the lining. b) Expanded fabricated flanged steel linings which are also generally similar t o the bolted cast iron lining but with special jacking recesses at the points of expansion of the linings. . their main use being as a secondary lining in water tunnels as discussed in Appendix 2.000 tonnes and for the twelve year period under review only the production for the LTE Victoria Line has been above this figure. c) Steel liner plates pressed from steel sheet metal. will probably confine the use of the bolted form of steel linings t o short lengths of tunnel subject to high or uneven loading except for the possible use of liner plates for small diameter tunnels. URS Infrastructure.Licensed copy from CIS: URS. Stanton and Staveley (a subsidiary of the British Steel Corporation) and Head Wrightson. providing comparable strength characteristics at lower costs than fabricated steel.000 tonnes and a trough of 6.000 tonnes with a correspondingly reduced peak of 33. The average production for use in the United Kingdom during this period was therefore approximately 18. represents less than one per cent of all cast iron production in the United Kingdom. Fortunately the foundries can often be turned over to casting other products during these lean periods.000 tonnes. During the peak period of 1964.000 and 40. During the last two decades the number of foundries casting segments has gradually reduced to two. Large differences in production requirements from year to year lead to considerable problems for the foundries in forecasting future demands and for budgeting for their investment on research and new casting plant. Uncontrolled Copy. In these instances steel has been used as a replacement to a grey iron lining. d) Steel circular membranes. 04/03/2015.000 tonnes. The preference for spheroidal graphite iron. Although these have been used extensively in the United States they have only been used in the United Kingdom for short sections of tunnel as temporary ground support.000 tonnes per annum with a peak of over 36. Fabricated steel segments have been used at openings or at special and transitional sections in tunnels where it would have been uneconomical or inadequate to cast a small number of segments in grey iron. average production of cast iron segments for the period 1963-74 excluding the Victoria Line was approximately 21. The main types of steel lining which have been used in the United Kingdom are: a) Bolted fabricated flanged steel lining of a form generally similar t o the bolted cast iron linings. These have not been used as a structural primary lining. A large number of tunnels.85 m internal diameter. it was not until 1869 that it was first used as a permanent lining for a tunnel.H. t o the present LTE Fleet Line tunnels of 3. During the next 4 5 years these linings were always specified for the deep tunnels in the London Underground.8 m internal diameter linings were erected in 20-30 minutes.1.4.1 t o 3. Bolted grey iron linings have continued t o be widely used for all tunnels in underground railways in waterbearing noncohesive ground where adequate waterproofing of the tunnels is essential (see Plate 1). concrete bolted linings (see Section 5. following Marc lsambard Brunel's patent for a shield in 1818. In the early years of the use of grey iron for tunnel linings an original design of lining was produced for each scheme as each project was owned by a different client1'. It is possible that. but due t o teething troubles. Table 2 4 in Appendix 3 shows how the internal diameters of the deep underground running tunnels in the London Underground have gradually increased from 3. but the majority have been for medium and large diameter tunnels for railways and roads. outfalls.6) while the short sections at the ends of the tunnel in less stable ground are lined in grey iron. with steel-faced precast concrete smooth bore grouted lining (see Section 5. concourse and station tunnels have still been in bolted grey iron. at present under construction. The London Underground system consists of shallow lines.3) have been introduced. Except for special sections in bad ground. Although these latter linings have been used extensively for running tunnels in good ground conditions. have been constructed with bolted grey iron linings during the last 1 0 0 years for all forms of tunnel use. the Tower Subway under the Tlianies.4) expanded concrete linings (see Section 5. machine chambers. All circular road tunnels under rivers have been constructed using bolted grey iron linings (see Plate 2) since the first Blackwall road tunnel under the River Tharnes (1892-97)17 until the construction of the Mersey Kingsway ~ u n n e l s (1967-74) l~ in Bunter Sandstone and the Dartford Duplication Tunnel. linings for escalators. In the 1890's mechanical excavators were introduced.1 Cast iron tunnel linings 4. Before that date the tunnels constructed. Medium diameter bolted grey iron linings were first used in deep running tunnels for the City and South a n d o n Railway in 188615 and for the Waterloo and City Railway for station and other associated tunnels in 89416. which were constructed using cut and cover methods t o carry large rolling stock and the deep lines constructed in tunnels t o carry smaller rolling stock than most underground railways. he would have incorporated a bolted grey iron lining in the Thames Tunnel (1815) if a circular cross-section had been chosen. At the turn of the century the Price machine was used on the London Underground Charing Cross t o Hampstead Railway and maximum rates of progress increased from 3 t o 4 m per day for hand excavation to 5 m per day1 6. With the increased demands on raw materials for re-armament purposes in 1937 and subsequently due t o the increased cost of bolted grey iron linings and t o technical advances. These two latter tunnels are lined. The 3. century for permanent linings for shafts. .1 nl internal diameter. tunnels under rivers and for large chambers these linings have not been used extensively for small diameter tunnels 15 . b u t it was not until J. Greathead designed the first circular shield for the Tower Subway that the linings were used in a tunnel 15 . for the City and South London Railway in 1886.1 Bolted grey iron tunnel linings: Although grey iron had been used since the end of the eighteenth Licensed copy from CIS: URS.1. 04/03/2015.with the exception of some sewer tunnels were of a non-circular cross-section. there was little increase in the rates of progress. in chalk. URS Infrastructure. in good ground. Details of some of these linings and the evolution of the joint details are discussed in Appendix 3. mainly in soft ground. The grey iron linings were usually erected behind a shield with the excavation carried out by hand. Two types of lining were normally used. a heavy lining for sections in waterbearing strata and a light section for London Clay or similar ground 1 6. Uncontrolled Copy.5) and expanded grey iron linings (see Section 4. With unmachined circumferential flanges a lip is cast at the back of the flange and the caulking carried o u t behind the bolts.6 m wide throughout the range. The minimum number of bolt holes per segment (apart from the key) for erection purposes is three. excluding the more recent road tunnels. two types of linings of different widths have often been used for different ground conditions. These linings can normally be erected more accurately than linings with unmachined circumferential joints although treated timber packings may be required t o keep the tunnel correct to line and level. The Curves (a). For larger schemes with a single diameter such as road tunnels. the stiffness of the adjacent rings is greatly increased and if well built the linings will sustain higher thrust loads from the shield rams.9 m internal diameter and 0.46 m wide above 4. caulking is thereby easier and quicker and the volume of lead required considerably reduced. Although the additional cost of machining exceeds these savings. while above 8 m the metric linings are lighter. 1 4 and 17. is milled on the front edge of the flange. while yarn or plastic tubing may be used in the joints for hand driven tunnels and shafts. Grummets are fitted o n all bolts for both machined and unmachined joints where watertightness is required. Since the 1330's a single lining has been specified in most types of strata up to depths of the order of 40 to 50 m. 04/03/2015. Where the circumferential flanges are machined a caulking groove. The first tunnels constructed with cast iron linings were built with continuous longitudinal joints but by the early 1900's it was customary t o erect linings with staggered joints. Bolt holes were originally cast into the flange as circular holes. The imperial linings are 0. preferably of wedged shape.5 1 m wide up t o 4. The early linings were generally cast in low quality grey iron there being no system of grading in existence. Timber or other packings are necessary in the joints to spread the thrust forces from the shield.e.9 m internal diameter. rather thall the two types used previously. This method has the additional benefit of improving the watertightness of the tunnel.Licensed copy from CIS: URS. For both grey iron and spheroidal graphite iron rusting of the two faces in contact partly seals the joints which are subsequently caulked. URS Infrastructure. 4 shows typical details of a grey iron bolted lining for the 1890's and the present day. rolling one ring compared with the next. and the new metric linings Curve (d). and with either machined or unmachined circumferential flanges. A comparison of the standard imperial linings Curve (c). but later elongated holes were introduced to allow for the inaccuracies in machinifig the radial joints with respect to the locations of the circumferential bolt holes.i. Although in very soft strata this may now be specified it is not a general practice except for large . and only occasionally the higher Grades. Tapered rings have been incorporated for many years for vertical and horizontal curves but more recently they have been used for controlling the alignment of the tunnel. plotted against the external diameter of the ring. 3 shows a graph of the weights of grey iron tunnel linings per metre. Uncontrolled Copy. One main improvement in cast iron linings in the last 30-40 years has been a reduction in the number of circumferential bolts (see Table 2 4 in Appendix 3). These rings are rolled t o the required pitch t o give the horizontal and vertical adjustment necessary to keep the tunnel correct for line and level without using timber or other packings. Fig. Grey iron bolted linings are available with machined longitudinal flanges. the bolt holes are now normally drilled circular. During the last 4 0 years Grades 1 0 o r 12 iron (see Appendix 3) have been specified. The metric linings were designed t o have machined circumferential flanges but due to production schedules this was not generally possible for the first stage of the LTE Fleet Line. while the new metric linings are 0. Through the years much discussion has taken place on the advantages and disadvantages of staggering or breaking joints . shows that for external diameters below 8 m the two curves are virtually identical. when large quantities are involved. employing jigs for precision location. Recent subaqueous tunnels have had linings with all joints machined. (b) and (c) are best fit curves for a large variety of lining types and diameters. With modern machining techniques. Fig. Licensed copy from CIS: URS. that this effect would be obtained without also using high strength friction grip bolts. with possible undesirable effects on the stability of the face.61 m. URS Infrastructure. In the United Kingdom spheroidal graphite iron has been used subsequently for a short length of arch construction for large concourses for two stations for the BR Liverpool Loop (see Plate 3 ) . The first experimental length of tunnel with this form of lining was constructed in June 1968 as a pilot tunnel for an enlargement for a crossover tunnel for the LTE Victoria Line extension to ~ r i x t o n ' ~details > ~ ~ of . however. this standard is still widely specified. In good cohesive materials or in weak rock under open ground and in particular where there is sufficient cover of good ground above and below the tunnel. Wider rings of spheroidal graphite linings may be used more readily since lighter sections may be designed with this material. 04/03/2015.2 Bolted spheroidal graphite iron tunnel linings: Spheroidal graphite bolted linings have only been used to date for short lengths of tunnel in the United Kingdom.diameter subaqueous tunnels in very weak ground where stiffness in bending is desirable.46 m and 0. for short lengths of the service tunnel. Other factors favouring lower widths have been the lower grade of cast iron. For the larger subaqueous tunnels the widthshave varied between 0. leading to overstressing and possible failure of the lining accompanied by more settlement at the surface. grouting capacities and risks of possible additional settlement. The width of the LTE linings has been restricted as they are required to be used either with or without a shield and the main criterion has been the weight of the segment for hand-driven tunnels. the rate of progress with bolted cast iron linings depends on the following factors: a) rate of excavation and removal of the material b) speed of erection of the lining c) speed of grouting d) width of ring Through the years the rate of excavation has generally increased considerably.1. or where mixed faces are expected. failure t o grout immediately may cause uneven loading on the lining after grouting. and for parts of the Tyneside Rapid Transit Scheme. as a result of the increasing use o f mechanical aids in the face and full face tunnelling machines. If large deformations of the lining occur. at cross passages and in areas of bad ground. In such circumstances grouting may be carried out at the end of the shift or during the erection of subsequent rings.46 m and 0. The results of this experimental length have encouraged a more general use of spheroidal graphite iron. is shown in Fig. for the Stage 2 Channel Tunnel* works. Until the 1950's. has increased only marginally in small diameter tunnels. it was customary to grout each ring immediately it was erected as the shield was shoved forward. which has mainly been for export. the width of cast iron rings used in the United Kingdom has generally been between 0. however. which are given in Appendix 3. the flanges may crack at the bolt holes. 2. however. In these instances. Apart from any question concerning the use of special expedients. 4. In non-cohesive ground. The method was introduced originally to help the building of the lining although it was also felt that there would be additional strength against bending in the longitudinal direction. It is unlikely. although mechanical methods of erection have helped considerably in the medium and large diameter tunnels. . The annual production of this form o f lining. * The Channel Tunnel Scheme was abandoned in 1975. some relaxation has often been allowed. Except for large diameter subaqueous tunnels. it is not recommended that any relaxation of grouting procedures are given. Uncontrolled Copy. The speed of erection of the lining.76 m as discussed above. With improved techniques in casting.5 mm compared with 19 mm for grey iron. Bolted spheroidal graphite linings are likely to be specified in the future more frequently for tunnels in the United Kingdom. however. also made the segments more susceptible to damage during handling. fractures could occur and a number of the segments in the crown had to be either replaced or strengthened with steel plates after the tunnel was complete. An experimental lining of this type was manufactured by Pont et Mousson for the French side of the Channel Tunnel Stage 2 Works.61 m. which was interchangeable with the conventional bolted grey iron lining of 3. with only minor modifica~ . There was a saving in the weight and therefore the cost of the grey iron per unit length of tunne1. 04/03/2015. eliminating the need for machining. Station tunnels in London Clay may be constructed with or without a shield and often running tunnels are taken through the station as pilot tunnels.in good cohesive ground. When a mechanical shield is used for the running tunnel the rates of progress for the . The reduced moment of resistance of the segments. Spheroidal graphite iron is currently being used on the Continent where its first extensive use was for the Vienna Underground railway. The lining. was later used for a total length of 3.0 km of the Victoria ~ i n e ' The discussed in detail in Appendix 3. A short experimental length was driven in 1958 which was later followed b y a 1.1. was not economical. These linings were 1.but the main advantage of the lining was the speed of erection and therefore the increase in the rate of advance of the tunnels. 4. because of the minimum casting thickness. below 5 to 6 m. spheroidal graphite iron is likely to be used for smaller diameters. Each sub-segment may be cast at high speed and accuracy.22 m wide respectively being generally wider than those used in the United Kingdom.9 km length of experimental tunnel for the LTE Victoria Line in 1960-6121. this form of lining is unlikely t o be used in preference to bolted or expanded concrete linings.5 mm gave a relatively narrow width for locating the shoes of the shield rams. When point loads built u p o n the lining.5 1 to 0. and the introduction of large capital cost equipment. One application meriting further study is that of fabricating segments from a number of simple pan-shaped sub-segments. except in waterbearing unstable strata or for lengths of tunnel subjected t o special conditions of loading or stability. More economical sections can be designed in spheroidal graphite iron with the neutral axis near the median of the cross section. while the width of the ring was increased from 0. These pilot tunnels have normally been lined in bolted grey iron or. The flanges were approximately half the depth of those for the bolted lining but slightly thicker. and the sub-segments glued together with epoxy resin to form the main segment. The lining. on account of voids or soft areas behind the lining. The total weight of each ring was similar. more recently. which were of comparable length to the conventional grey iron lining. Uncontrolled Copy.3 Expanded grey iron tunnel linings: The expanded articulated grey iron lining was developed between 1949 and the late 1950's. For larger tunnels the saving in the weight of the lining more than offsets the large increase in the cost of the cast material over that of grey iron linings (see Chapter 11).0 and 1.Licensed copy from CIS: URS. In the early 1970's the use of spheroidal graphite bolted linings for small and medium diameter tunnels. with fewer bolts. leads to consequential savings in the cost of erection. In addition the use of wider segments. when compared with grey iron bolted linings.71 m internal diameter. Spheroidal graphite bolted linings have been exported to San Paulo for the metro scheme and for the Washington Metro. in expanded concrete linings if the future station tunnels are t o be constructed with a shield. However. lining is shown in Plate 4 and tions. The present normal minimum casting thickness for the skin is of the order of 12. had six segments per ring. URS Infrastructure. The small flange depth of 63. When Dungeness 'B' Power Station was constructed. due to excessive shove forces resulting from the small size of the ports in the diaphragm of the shield. construction of these pilot tunnels in conventional bolted grey iron are low. The lining for the inlet tunnels was redesigned in steel to take these excessive loads. Details of these linings are given in Appendix 3. b) For special segments at openings in cast iron tunnels where it would be uneconomical to use cast iron segments or where lintel beams are required. lengths of running tunnels were constructed using this lining as an alternative t o the expanded articulated cast iron or concrete linings.2. At Dungeness 'A' Power Station the original lining for the inlet tunnel was of cast iron but. (See Plate 6). In these permanent conditions steel wedges and packings or cast iron machined packings and wedges were used. The use of special segments at openings in cast iron lined tunnels is discussed in Section 8. compared with grey iron. discussed in Section 4.1. The lining? have been used in two main conditions: a) For lengths of tunnel where excessive loads have been expected either from the shield during the construction or from the ground.1. although designs were considered for possible use in sections of the Channel Tunnel. for approximately 0 . a few years later. The total length constructed for both pilot and permanent tunnels for the LTE Victoria Line and Piccadilly Line extension was 1. This form of lining has recently also been used in the LTE Piccadilly Line extension t o Heathrow. During the construction of the LTE Victoria Line. Uncontrolled Copy. In the United Kingdom there has only been one recent example of a long tunnel in bolted steel linings. Future applications of expanded cast iron linings for permanent conditions will probably be in spheroidal graphite iron which has superior tensile characteristics t o grey iron thus avoiding some of the difficulties encountered t o date.Licensed copy from CIS: URS.4 Expanded spheroidal graphite iron tunnel linings: Expanded tunnel linings in spheroidal graphite iron have not been used for lining tunnels to date. A form of expanded temporary lining using timber packings in the longitudinaljoints between segmentswas developed and used for a number of station pilot tunnels (see Appendix 3). the flanges of the iron cracked. Steel linings have been used in several schemes in the United States and in Europe .in particular at Chicago. and the reduced erection time would considerably reduce the cost differential between cast iron linings and concrete linings. a new steel lining was designed for both the outfall and inlet tunnels.3. These linings would be cast and expanded in much the same manner as the grey iron expanded lining. .3.1 Bolted steel tunnel linings: The fabricated bolted flanged steel linings are made up of segments of a similar form to the bolted cast iron lining. 04/03/2015. 4.2 Steel tunnel linings 4.4 km. Following the experimental use of the expanded bolted grey iron lining for pilot tunnels. The saving in the weight of the material. experiments were carried out with methods of expanding these bolted linings22. 3 km of pilot tunnels for the crossover to the east of Heathrow Central Station (see Plate 5). 4. San Francisco and Vienna. URS Infrastructure. causing high bending moments or tensile stresses. A bolted steel lining has also been designed for twin railway tunnels in compressible silt under the River Ij in Amsterdam where a strong stiff lining would be required (see Appendix 3). 4. 5. the Victoria Line tunnels passed beneath three BR lines and the LTE Circle Line tunnel. and at Kings Cross Station2 3. The Armco liner plate. This. and the concourse tunnel. No significant deformation o f t h e lining was recorded and the columns in the store settled less than 1.3 Liner plates: Two forms of thin pressed steel segmental linings. Details of the lining construction are given in Appendix 3 (see Plate 7). however. the load later being taken by steel wedges or wedges and rockers. The Commercial Hydraulics lining is flanged and bolted in both the circumferential and radial directions. At both Oxford Circus and King's Cross these tunnels were instrumented and details of the results are given in Appendix 6.2 Expanded steel tunnel linings: Expanded flanged steel linings were used for short lengths of tunnel on two contracts for the LTE Victoria Line.2. details of which are given in Appendix 3 (see Plate 8). At Oxford Circus the hoop load built up within five months to approximately 90 per cent o f t h e overburden pressure based on the loadings from the store and depth of the clay24.48 m internal diameter southbound station tunnel was only a metre or so below the third basement of Peter Robinson's store. In tliese conditions the plates are not given special protection against corrosion.4 M N / ~ ' were indicated. At King's Cross the hoop load after seven months was approximately 55 per cent of the overburden pressure for the northbound station tunnel and after five months was just over 9 0 per cent for the concourse tunnel. both of which are manufactured on the continent.63 m internal diameter. This lining is lapped and bolted in both the circumferential and longitudinal directions (see Plate 10). An expanded steel lining which was grouted in the crown was designed t o prevent possible settlement of the footings and to accommodate the jacking stresses.5 m below the footings o f the brick arches o f the BR twin track Midland Curve and single track Hotel Curve which were built without inverts. The linings were used a t Oxford Circus Station. The crown of the northbound station tunnel. The maximum settlement of the brick arch tunnels was of the order of 37. where heavy or eccentric loads were expected close t o the lining. This Multiplate lining is manufactured in the UK. Uncontrolled Copy. Recently the linings have been used for a number of contracts which were specified as pipes laid in timber headings and for which the contractor put forward liner plates as an alternative for the ground support before laying the pipes. and over the LTE Northern Line and Piccadilly Line tunnels. called liner plates.5 mm half of which was associated with the construction o f the cross passages. jacks of 100 tonne capacity were used for expanding the linings. passed some 1. 04/03/2015.4. At Oxford Circus Station the crown of the 6.are generally available in the United Kingdom. For both the Oxford Circus tunnel and the King's Cross tunnels. 6. Licensed copy from CIS: URS. URS Infrastructure. At King's Cross. and thus the new tunnels gradually traversed below the concentrated point loads from these arches giving eccentric loadings.32 m internal diameter. Details of these linings and data on a number of schemes in which the linings have been used are given in Appendix 3. The design of the upper half of the lining was complicated by the fact that the tunnels passed below the brick arches at an oblique angle. was only equivalent to about 5 0 per cent of overburden based on the full depth of clay. this is used as a temporary ground support with a cast in-situ concrete primary lining26 (see Plate 11). To prevent settlement of the brick arches an expanded steel lining was designed for b o t h the northbound station tunnel and the concourse tunnel. These linings have been used in only a few instances in the United Kingdom although their use has increased during the last few years. Complete details of the foundations were n o t available before excavation commenced but loads of the order of 0. 17 . designed as a primary lining for the permanent ground conditions. A second form is also available with more corrugations. which is used for relining old tunnels. While the demand is small it is not economical to manufacture t h e plates in this country and thus there are additional importing costs.5 mm. The segments are flanged and bolted in the circumferential direction a n d lapped and bolted in the radial direction. is galvanised and does not require a n internal lining unless a smooth bore is required2' (see Plate 9).2. 5. Records of the delivery of precast concrete segments and of site cast segments are given in Section 3. URS Infrastructure. These linings are suitable for most ground conditions. the segments have been cast on or close t o the site. c) Smooth bore grouted precast concrete linings were the first form of precast concrete lining t o be introduced (1903) but only became available as standard linings in the late 1950's. For expanded linings. and the incomplete data for the 1960's have therefore not been included. the different types of precast concrete tunnel linings and their manufacture are discussed. but such moulds have been found t o distort excessively.5). b u t their use in self supporting clays has increased considerably during the last decade.Additional moulds may be cast whenever . These linings. composite steel/aluminium moulds o r . These linings were first introduced in the late 1930's and are available as a standard lining and cover the majority of the present day market in precast concrete linings. which are of the smooth bore type. Records were only available from some of the precasting manufacturers for the previous years. steel and concrete ~nouldsConcrete segments may be cast in all-concrete moulds. all steel moulds.5. with further data in Appendix 4.2 and Appendix 2 for the period 1970-76. This is not usually economical for standard linings. or dowelled linings of a similar form to the bolted cast iron linings. 04/03/2015. During the 1939-45 war various types of moulds were investigated 77 . Uncontrolled Copy.1 Moulds Little information is generally available on the manufacture of the early concrete segments but these were generally cast in steel or cast iron moulds. concrete moulds with timber sides. including timber. Concrete moulds for each particular manufacturer's bolted segments are all cast from concrete master segments in the casting yard. on account of the relatively small number of schemes. In the following sections. thus all segments should be identica~'~. Use of these linings is generally confined to tunnels in soft ground or weak rock. Precast concrete tunnel linings were first introduced in the United Kingdom in 1903 but were not used extensively until the 1930's and were not available as standard linings until the late 1940's and early 1950's. A few segments have been cast from aluminium moulds with timber sides. Four main types of lining have been used: a) Bolted precast concrete linings. records are available since 1950 when these linings were first used (see Section 5. d) Expanded grouted precast concrete linings are the latest form of precast concrete lining and have recently been used for the first time in weak rock in the Service Tunnel for the Channel Tunnel Stage 2 Works. Precast concrete linings are generally cast in manufacturer's works and transported t o the sites by road. for the smaller segments. except where the size of the individual segments is large. b) Expanded precast concrete flexible linings were first introduced for small diameter tunnels in London Clay. however. PRECAST CONCRETE TUNNEL LININGS Licensed copy from CIS: URS. fibre glass. usually of large size and using special linings. For a relatively small number of schemes. are not generally available as standard linings. URS Infrastructure. Reinforcing bars have also been used to a small extent as aids to building the ring of the lining. or (ii) to withstand the permanent ground load conditions. 4 or 6 segments 250-350 All steel Horizontally 250-350 Composite steel and aluminium Horizontally 250-350 generally.2 Steel reinforcement Steel reinforcement may be provided in precast concrete segments either (i) to increase the section resistance to tensile and bending stresses imposed during the temporary conditions of handling and erecting the lining. 04/03/2015. Uncontrolled Copy. as in the case of the McAlpine lining and the Charcon . All moulds should be regularly inspected and concrete moulds refurbished when required: the refurbishing of steel moulds is often expensive. Although steel moulds have occasionally been fabricated at the precasting yard. with their extrados upwards. 600 in certain instances Fibre glass Horizontally up to 6 0 0 All steel Vertically. Table 4 summarises the different moulds and linings. singly or in pairs 100-350 but depends more o n programme Composite steel and aluminium Vertically Up to 800 have been obtained Type of linings Types of mould Bolted grouted Smooth bore grouted or expanded Special segments 5. and shoving the shield. required to suit the programme or to replace wornout moulds. The methods of manufacture of concrete moulds are discussed in Appendix 4 and Plates 12 and 1 3 show typical concrete andxteel moulds. they are usually obtained from an outside supplier. The special segments for larger diameter tunnels are normally cast in a vertical position. TABLE 4 Moulds for precast concrete segments Casting method Average number of castings per mould Concrete with timber sides Horizontally 250-350 All steel Horizontally 250-350 Composite steel and aluminium Horizontally 250-350 Concrete with timber sides Horizontally 250-350 All concrete Horizontally or Vertically in 2 . In some instances 600 or 800 uses of the moulds have been obtained where special care has been taken in the design.Licensed copy from CIS: URS. 4 or 6 segments thus saving considerable space in the casting area and the mould storage area. The segments for the bolted linings and for many of the smooth bore grouted linings are cast in a horizontal position. in steel moulds and often in special precasting yards at or near the site. Both forms of moulds are normally used for between 250 and 350 castings. fabrication and use of the moulds (see Appendix 4). on their sides. The smaller solid concrete segments with plane or slightly curved radial joints may be cast in a vertical position on their sides in groups of 2 . 1 where the option of adding reinf~rcementis compared with the alternative of a n additional thickness of concrete. Reinforcement is costly to use in precast concrete segments as the labour costs of bending and fixing the relatively short lengths.6). are high in relation to the weight of the steel. the expanded Wedge Block lining (see Section 5. In Appendix 4 the minimum cover t o reinforcement is discussed in relation t o the corrosion of reinforced precast concrete.Universal lining (see Section 5.1. For plane joints some relief from local overstress between abutting concrete faces may be achieved by coating the surfaces with bituminous paint or similar compound or. i. 5. 5.1 Plane or helical joints The longitudinal joint for all standard bolted linings (see Section 5. with greater effe.4). often to close tolerances. 2) The reinforcement required in the vicinity of the longitudinal joint: consider alternative joint design and the possibility of packing pieces t o improve load distribution. 5 . Uncontrolled Copy. For wedge shaped segments all longitudinal joints are helical.3 Joints Four main types of joints are used in precast concrete linings: a) Plane or helical joint b) Concave/convex joint C) Convex/convex joint d) Tongue and groove joint These types o f joints are shown in Fig.aspect ratio of segment (see l(a) above). 3) The reinforcement required to withstand secondary stresses caused by ground loads: consider changes of .e. URS Infrastructure.ct. . A number of examples of reinforced precast segments are discussed in Appendix 4. the ratio of the length or width of segment to the thickness. In general the cover to reinforcement for precast segments is 13 t o 25 mm except for special linings which may be in contact with seawater or a similar aggressive environment where the cover should be 25 mm t o 40 mm. 1) The reinforcement required for handling: consider a) reductions of aspect ratio of the segment.3. b) alternative means of reducing vulnerability t o damage. When designing segments for special schemes the principal factors concerning the use of reinforcement t o be considered are as follows: Licensed copy from CIS: URS. This point is discussed in some detail in Section 11.6) are all plane joints and similarly the circumferential joint of most other forms of lining. In addition the presence of the reinforcement in the mould will add t o the costs of casting the segments. a bituminous felt or other packing piece inserted in the joint. 04/03/2015.5) and the smooth bore grouted Universal lining (see Section 5. The edges of solid segments with plane joints may be chamfered t o reduce the risk of local spalling. 04/03/2015. 5. The design of an articulated joint is a critical feature in the design of the lining as it largely determines the areas of maximum compressive and tensile stress concentration.5) were convex/convex in both the longitudinal and radial directions (see Fig. in practice with expanded linings this does not always happen.3. on account of friction in the joint. It was expected. The concave/convex joint is intended to act as a self-centering joint which helps in the erection of the lining.74 m and a total length of 4. it is desirable that the ring should consist of a number of segments. The history of the lining is discussed in Appendix 4.6). as for the smooth bore grouted Flexilok and Rapid linings (see Section 5. T o limit bending moments in the individual segments. probably a minimum of 1 0 to 12. by compression and shear between the ground and the lining.4 tonnes) compared with the cast iron ring (1. 5. during the construction of the eastward extension of the LTE Central Line.Licensed copy from CIS: URS. The main features of the lining were the introduction of concrete stiffeners which helped to take the shield ram forces.4 km of running tunnel was constructed using the lining. and the reduction of the number of bolts in each circumferential joint from 52 for the corresponding conventional grey iron lining to 3 129 .distribution of load from thrust rams may present problems on account of the thin concrete section available. there was the likelihood of a shortage of cast iron. Uncontrolled Copy.3. The internal diameter of the final lining was 3. This form of joint avoided the risk of concentrations of load near the edge of the segment which may be a cause of damage where the ring has not been built square and true.2 Concave/convex and convex/convex joints: The concave/convex joint and the convex/convex joint are articulated longitudinal joints which ensure that the load is transmitted near the centroid of the section and allow the ring to take up the shape of the excavation. It was realised that the concrete segments would not stand up to the rough handling given to the grey iron segments and that additional care would be required by the miners. Further developments are proceeding to refine the geometry of such joints. Although the lining was introduced originally to overcome the difficulty arising out of the shortage of cast iron it was hoped that the lining would lead to appreciable reductions in the cost of tunnelling and on that contract the manufacturing cost of the concrete lining was about 60 per cent of the cost of the grey iron lining.4 Bolted and dowelled tunnel linings In 1937. however. and thus the need of reinforcement.3 Tonge and groove joints: The tongue and groove profile is normally confined to the circumferential joint. to give adequate flexibility of movement at the joints. is mobilised to achieve equilibrium. investigations were started on a precast reinforced concrete lining of similar form t o the traditional cast iron lining. the joints can be considered to be placed centrally as there is little play in the bolting of the formerring. The principle of the design of articulated linings is that inequality in applied loading from the ground will cause the ring to deform until sufficient passive loading. may be taken to vary approximately linearly with L2 . URS Infrastructure.6 tonnes) the same progress would be . and eccentric loading can occur. In Appendix 4 the different types of linings that have recently been used are listed with details of their joints. The convex/convex joint is more readily designed as an unreinforced joint than the concave/convex joint for which reinforcement is generally required near the concave face to prevent bursting. For a solid segment of aspect ratio L (circumferential length to radial thickness) the secondary stresses r caused by uneven loading around the ring. 5). The longitudinal joints of the expanded lining for the LTE Fleet Line (see Section 5. For thin segments in shield driven tunnels. When former rings are used for the erection of the lining. that with the slightly reduced weight of the concrete ring (1. The shaped joint provides some security in locating segments during erection. 5. The number of circumferential bolts has been reduced and the number of reinforcing bars in each of the flanges reduced from four to two (see Plate 15). In practice. Uncontrolled Copy. URS Infrastructure. During the 1939-45 war this form of lining was used extensively for tunnels and air raid shelters. The depth of the flanges of the larger diameter tunnels was similar t o that for the cast iron linings to provide the same internal diameter for corresponding external diameters and to allow for the interchange of the two types of lining when used behind a shield. the time required to erect both types of rings was approximately 2 0 minutes. A number of tunnels have been lined internally with sheets of resin mortar or fibre glass reinforced plastic. These internal linings are discussed in Appendix 2 . has reduced (see Chapter 1 1). . 430 m long. adjacent to existing LTE Stations. especially in the diameters below 3 m for the sewer market. These segments were later replaced3' (see Section 5.03 ni internal diameter tunnels. an internal or secondary lining is required when a bolted concrete lining is used for the primary lining. This market has increased considerably over the last decade and with the help of improved production and quality control methods the cost of these linings.61 m for the whole range of diameters while the depth of the flanges has been increased and the flange width decreased. The linings for the standard range of diameters now available are of a design modified from those used in the war years31. in London. 04/03/2015.03 m internal diameter tunnels in London a number of segments fractured.obtained. The niiijority of these tunnels were at depths of less than 30 In. Licensed copy from CIS: URS.5): Bituniinous packings were inserted in the radial joints for most of the early schemes.5 1 m but this was increased to 0. Where it is necessary for a tunnel t o have a smooth bore finish.44 m . For the larger diameter tunnels the width of the ring was 0. The width of the ring has been increased to 0. Special steel thrust ribs and rubber pads were designed for the shield rams to enable the thrust t o be transferred through the skin of the linings.03 m internal diameter mainly at a minimum depth of 37 In 27 . two thirds of which were lined with bolted concrete linings. this was partly caused b y distortion of the ring by the faulty erection of the key segments. in real terms. as for a sewer or water tunnel. b u t with increases in cost and the reduction in the number of skilled tunnel bricklayers. and 5. During the construction of the 5. Inany being shield driven. when such packings were omitted squatting of the tunnel sometimes caused excess local loading of the flanges with consequential cracking. Only in the last few years have these standard linings been used more generally for larger diameter tunnels. Originally the standard linings were used mainly in tunnels of small diameter (up to 4 m) and for shafts for the larger diameters. These internal linings were originally o f brick. Following the 1939-45 war the use of the bolted concrete linings increased considerably. These standard linings have been used in all types of ground conditions and account for the major part of the small diameter market. Two interesting uses during this period were: a) eight air raid shelters each of twin 5.61 m for the smaller diameters. (See Plate 14). cast in-situ concrete or precast infill panels are now normally used. The design of all these linings was based on the original design for the LTE Central Line running tunnels. b) a series of tunnels for the War Office on the Dorset coast of 2. after educating the miners in new techniques. 2 1 In 1955 the Building Research Establishment (BRE) carried out an experiment for London Transport on three cast iron rings in an old deep running tunnel adjacent to new tunnelling38. high ram thrusts may impose excessive loads on the skin of the lining.4 m internal diameter or above. thus confirming that the joints transmitted small bending moments. locating dowels and sockets for the interlock between the solid segments both longitudinally and Ltd 31 with circumferentially.37 was introduced in 1950. until completion of grouting. . however.Licensed copy from CIS: URS. Before tunnelling commenced strain gauges were fitted to the rings as large deformations were expected. URS Infrastructure.85 m to 10. Where steering is a problem a compensating bead should be fitted to the shield. Many of these schemes have been for tunnels at depths greater than 3 0 m or where large pressures were expected from the shield rams.61 m . Recently an alternative design with a solid invert called the Smoothvert lining has been introducted by Buchan Concrete . A new lining which can be bolted and grouted. The longitudinal joint bolts were used chiefly to help the erection of the ring and little bending moment could be carried by these joints. The use of solid invert segments reduces the cost of cleaning up the tunnel compared with the conventional bolted lining and reduces the possibility of cracking invert segments by excessive ram pressures (see Plate 16 and Appendix 4). a result expected from analysis of the conditions. Bolted concrete linings of up to 1 m width have been widely used overseas. With the increased use of bolted concrete linings for larger shield driven tunnels it is llkely that the width of larger diameter rings may be increased. In the United Kingdom the width of the bolted rings is generally 0. Frequently the bolts were omitted or not fully tightened. In such cases the hoop load was virtually concentrated in the skin with average stresses of the order of 14 MN/m2. Uncontrolled Copy. The width of segments has been dictated in the main by the weight that can easily be handled.76 m width33>34. although a number of schemes have used linings of 0. As the first result of these studies the Don-Seg lining36. Where ground conditions permit the degree of burial of the cutting edge should be controlled with the minimum trimming of the excavation carried out by the shield during the shoving. Special bolted concrete linings have been designed for a number of schemes of 2. These experiences led in the late 1940's to studies to develop a lining that could be expanded into the ground. All the other segments are common t o both types of lining32. one at each of the knees. require more reinforcement for handling purposes than that required for the permanent conditions. or expanded. deduced from strain readings on adjacent cast iron rings.5 Expaoded concrete tunnel linings Investigations of a fairly widespread fracture of the concrete flanges of a bolted concrete lining in a tunnel during the mid 1940's showed that incorrect positioning of the key segment had resulted in eccentric loading of the flanges3'. a constraint reduced by the increasing use of mechanical handling. 5. Excessive thrusts are normally avoidable if adequate supervision is provided at the face.0 m. 04/03/2015. It was recognised that bolting of the circumferential joints was only essential for erection purposes. When the bolts in the longitudinal joints were subsequently slackened there was little effect on the strain distribution in the segments. In a shield driven tunnel. which was later followed by linings for the Greenwood to Potters Bar tunnels35 and for the experimental length of the LTE Victoria Line. The lining should therefore be designed for the expected ram thrusts to avoid cracking of the skin. and in water-bearing ground for waterproofing reasons. thus avoiding the necessity for bolting and grouting of the lining. The bolted lining will have a key segment near the crown while for the expanded lining this is replaced by two small wedges. The larger segments may. has recently been designed for the LTE for a range of diameters from 3. Data on a number of these schemes are given in Appendix 4. The ground has varied from soft clay t o hard and blocky clay and. until the lining is expanded. is often used to reduce the friction between the ground and the back of the lining during the expanding operation. mechanical or hand. but also reduce the reliance on 'stand-up' time for the ground. Any voids caused by over excavation can be filled with a soft clay and back grouted at a later date to ensure even loading on the lining. Expanded linings have been used subsequently in 32 tunnelling schemes over a period of 25 years for a total length of over 150 km. the ground moves onto the shield relatively quickly and consequently a wedge or block of reduced circumferential length may be necessary to avoid overstressing of the ring. must be used for a tunnel with an expanded lining to give an accurately excavated profile t o provide an even bed for the completed lining. Eight forms o f expanded linings have been developed during this period. Halcrow lining (see Plate 20) and the Mott Hay and Anderson designed for t h e LTE .for the Victoria ~ i n e ' the lining (see Plate 21) and another Halcrow lining for the Fleet Line and for the extension for the Piccadilly line 42 (see Plate 22). they have also been used in Lias Clay and the Gault. URS Infrastructure. Although the majority of tunnels constructed with expanded linings have been in London Clay. the other by one or more circumferential jacks which expand the ring. This expedient has been used successfully in both the Metropolitan Water Board (MWB).1). The linings. When the rings are expanded by more than one wedge or jack it may be necessary t o adjust the sequence of the operation if holes in the segments for brackets t o carry cables or other services are to be accurately aligned between adjacent rings. now the Thames Water Authority (TWA).Licensed copy from CIS: URS. For soft clay. A shield. The first expanded lining t o be used in the United Kingdom was the Don-Seg lining for the experimental tunnel for the MWB Thames-Lee Valley scheme in 1950-5 I 36. . The Don-Seg and Wedge Block linings together account for approximately 8 0 per cent o f the total length of tunnel constructed using expanded concrete linings. Expanded concrete linings were first used for medium diameter tunnels on the LTE experimental length of running tunnel for the Victoria Line in 196121 (see Plate 19). partly due to the quicker erection of the segments with no delays for bolting and grouting operations and partly.40 The Wedge Block lining. trailing head boards may be used. Subsequently three different linings have been ~ . the ring being expanded against the boards and grouted after shoving for the next ring. Alternatively. Both linings are expanded by the use of one or more wedges. temporarily supporting the ground. Table 5 gives basic data on each of these linings which are mentioned below and discussed in Appendix 4. Alternatively. with bands of rock and claystones. A lubricant. 39. immediately ahead of lining and the working face. Two basic methods of expansion have been used. for mechanical shields. Rates of progress for both hand and mechanical shields have increased dramatically with the use o f expanded linings. When building expanded linings additional care is required to ensure that the face of the circumferential joint is always in plane. thus forming one o r more spaces to be filled either with dry pack concrete o r a close fitting concrete block. Increased driving rates not only directly reduce the overall cost of tunnelling. (see Plate 17) was developed from the Don-Seg lining (see Plate 18) by the M W B ~ ~ and was first used in 1955. t o improved designs (see Section 10. an adjustable bead may be used on the front of the shield or a tail bead at the rear of the shield finally t o trim the clay. occasionally. Where bands o f claystone or rock are encountered a slightly increased circumference of ring may be required. 04/03/2015. are erected in the usual sequence with the top half held either on the erector arm or on support bars from t h e shield or b y the shove rams. Uncontrolled Copy. such as soap solution o r bentonite. The expansion of the ring is usually carried out either in the crown or near the axis level or knee joint of the lining. one using wedged shaped blocks which are shoved longitudinally by a ram on the shield to stress the ring against the ground. which are of solid segments and usually unreinforced.and LTE tunnels. 04/03/2015. . The lining for the rest of the two tunnels was designed to have the same thickness of 152 mm. on the Piccadilly Line extension some 1000 rings of the Victoria Line. Uncontrolled Copy TABLE 5 Expanded concrete tunnel linings N cn * t a trial length of 5 0 metres was constructed in this thinner lining. Mott Hay and Anderson lining were used for the first section of one of the two tunnels. URS Infrastructure.Licensed copy from CIS: URS. The articulated joint was first used for the experimental length of the Victoria Line. Fig. 5.3). All subsequent medium and large diameter expanded linings have used this type of joint either in the convex/concave form or the convex/convex form (see Section 5. subdivided into different types of expanded lining. The major use of these linings has been for water tunnels. In difficult ground or adjacent to portals a tail was attached to the shield and the drive continued in cast iron lining.08 m internal diameter.3 k m to 2 7 k m . The present generation of smooth bore linings was introduced in the late 1950's and 1960's following the introduction of the bolted and expanded precast concrete linings. with lengths varying fro111 0. and increases costs. which reduces progress. In developing expanded linings the use of an alternative lining must be foreseen which can be quickly and easily interchanged with the expanded lining if difficult ground conditions are encountered.The first use of an expanded lining in a large diameter tunnel. Usually the internal diameters are kept similar. During this period six projects were under construction using the Wedge Block lining. the annual length of tunnel constructed has varied considerably. The total volunle of tunnel excavated has increased only marginally since the increased length of tunnels is in the smaller range of diameters. The Don-Seg lining has also been used for a number of tunnels in Belgium.lining with several modifications was used intermittently until the early 1960's. The Greenwood to Potters Bar linings had tongue and groove longitudinal and circumferential joints. where the annual length constructed has doubled in the last ten years. 8. while the circumferential joints of b o t h linings and the other longitudinal joints of the Wedge Block lining were flat surfaces. Uncontrolled Copy. the present depths of the flanges are not compatible. the 10.3 m internal diameter Cargo Vehicular tunnel at Heathrow Airport London. In 1966-68 the largest tunnel with an expanded lining. The total number of projects under construction during these periods is also shown. and were therefore part of a surface of a helix. URS Infrastructure. Expanded linings have only recently been used in sewer tunnels . or if the excavated diameter is t o be kept constant there must be some reduction in the finished diameter o f the grouted lining.the major sector of tunnelling in the United Kingdom.6 Grouted smooth bore concrete tunnel linings The grouted smooth bore form of precast concrete lining was first introduced in 1903 when the McAlpine lining was used for an experimental tunnel for a sewer in ~ l a s g o w This ~ ~ . two LTE projects and one project using the Don-Seg lining. . On account of the small number of schemes using expanded concrete linings. A trial length of sewer tunnel using a new expanded lining called the collinsa lining was carried o u t in Stoke in mid 1974 (see Plate 25). For smaller diameter tunnels. Several of these linings have articulated joints as described in Section 5. however. The longitudinal inclined joints of the Don-Seg lining and the wedge joints for the Wedge Block lining were designed for full face contact. was constructed for the British Airports Authority H BAA)^^ (see Plate 24). The histogram shows that the use of expanded linings is generally increasing although at times such as the early 1960's and mid 1970's. The thickness of the concrete lining was compatible with the thickness of the cast iron linings plus the grouting space. Licensed copy from CIS: URS. was for three railway tunnels for the BR Greenwood to Potters Bar duplication in 1 9 5 5 ~ ' (see Plate 23). 7 gives the annual lengths of tunnel constructed for the period 1970-76 and shows the fluctuation between successive years. This increase in length is almost solely due to the use of the Wedge Block lining under licence to the TWA. 6 shows a histogram of the total lengths of tunnel constructed and the total volume of tunnel excavated for each of the 5 year periods since 1950. 04/03/2015.3. Fig. For the LTE running tunnels and the BR Greenwood to Potters Bar railway tunnels the concrete linings were designed to be interchangeable with standard bolted cast iron linings. where a standard bolted concrete lining is used in difficult ground conditions. there has been a temporary decline. If the internal diameter is to be kept constant excavation is necessary outside the diameter of the shield. The linings have been used in all strata from soft silts to extremely strong rock. made in sections. However.47 . Uncontrolled Copy. The number of segments to the ring is usually higher than for a bolted lining t o reduce the bending moments in the segments. the weight for handling purposes and damage during handling and erection. These forms of erection d o not require a shield. having a smooth bore internal finish which does not require a secondary lining. The smooth bore linings fall into two main categories: a) The standard ranges of tunnel linings manufactured mainly for sewer tunnels. URS Infrastructure. The Flexilok and Rapid linings use a temporary steel channel segmental former ring which is removed when the grout is set.Flexilok and Extraflex linings. The thickness of the lining is similar to that for the bolted lining of the same diameter (see Plate 28). The segments are solid and effectively unreinforced. with the exception of the three-segment Mini tunnel. The Spun Concrete Extraflex lining was developed in the middle 1960's for tunnels through areas where future mining is anticipated46. Caulking grooves are cast into the internal edges of all joint faces for sealing the joints with a caulking compound or mortar pointing. During 1976 and 1977 two new smoothbore linings have been introduced by Empire Stone Ltd and Croxden Gravels respectively. namely: McAlpine lining. The standard smooth bore concrete linings are generally of a similar cost to the standard bolted concrete linings and erection times and costs are generally similar. 04/03/2015.F. This was later changed t o conventional casting methods (see Plate 26). The majority of tunnels in these linings. The basis of the lining is similar to that of the Flexilok lining with the exception that the circumferential joint has been changed from the knuckle form to a spigot and socket joint t o allow for horizontal strain and tilting between adjacent rings (see Plate 27). Rees Ltd . within the thickness of the ring.Licensed copy from CIS: URS. Table 6 gives data on each of the linings which are also briefly mentioned below and described in detail in Appendix 4. while the Universal and the McAlpine linings incorporate permanent hoop bars. except where dictated by the ground. however. require a temporary or permanent circular support for erection purposes. b) The special linings developed by one engineer or contractor or for individual contracts. and in a few instances in compressed air. It is usually recommended that the unbolted linings are not used in a length of tunnel that requires blasting as the linings tend t o squat in response to the transient pressure waves. The Spun Concrete Flexilok lining was developed during the 1950's38>46 as an alternative to the laying of pipes in timbered heading or to the use of bolted concrete lining. The standard smooth bore linings. there is a substantial saving in programme time as no secondary lining is required and the costs of cleaning out the tunnel at the end of the drive are reduced.Mini tunnel. have not been in waterbearing strata. The standard range of smooth bore linings was first introduced as an alternative t o the bolted precast lining in soft ground and weak to moderately strong rock in conditions which were unsuitable for expanded linings. with and without hand shields. The initial manufacture was based on the firm's long experience in casting pipes and the segments were spun in rings of segments. The Charcon Rapid lining was developed in the early 1960's for a similar market to the Flexilok lining38.Rapid and Universal linings and W. . namely: Spun Concrete Ltd . and are therefore suitable for short lengths of tunnel. Mersey Kingsway Road Tunnels and Dartford Duplication Road Tunnel. Charcon Tunnels Ltd . S . 04/03/2015. m d I I C'II.X .0 I I - 8 C'I 2 N 0 I 2 m - 9 9 $ m u d-111 !m a m! m F I - 111 52 a d ! 0 c 1 11 + \? o? I \? t 3 P - .-F -. d 2 "3 I a 111 0 I - v. Uncontrolled Copy. e . a ? P s T J z 5s e-14 r 2 r c a$ 8 . 4 0) . . 0 0 2 I. Z N $ f3 - + ~c PI m o z m I m "! c 4 ". 2 " 2S v l -U .I 2 w ~ -+ I c% Y m m P M E X L4 + e. w 4 U - - & 0 x 2.. 0 0 0 - ". 111 X c c e. m ". m w o 'QP o m P N m w 2I -- m M I 2 m P ~r 'Q m m d 2 . a. u! m 111. m z .O E 9. 5 a* 2 5 Z c Qzz E 2 $ 2 & x e.2 " n e.5 x b s d d m -G Y e.2.d +. .E + C O P - 2 -m1 b - 2 - - % 1 a 2 c .C x 'L-b b E - e. c% m a! u ! 2 a!. 2 % 2 c Y * 0 0 m m m % w s d e. URS Infrastructure. e.osa fE -G ~I m l =! o M w I I V3 C 0 P ZZ5 'g E F E S ' 2 p * -- e NC'I m g 2 + m m 'Q g z 2 2 0 0 -- a0 0 .-0 . m d 2 2 m 0 P 2 2 2 2 P \D m 2 3 C .X m 'Q. 2 o z .-a m 2 - V) m i = P . ? - .o w G - c . 9. m 0 fl OC) 2> e >.% Yo3 g a 0 0 * X a.4- 0 + 5.x Licensed copy from CIS: URS. > > "-08 S 3 g $ S > m 0 U G F v X + 'Q 'Q 2 2 m - m I a m x . 0 2 - 3 % . e.2gj. m I 0 I 'QP I 0 I 1 I m m 2 a I o o m~ I I - m co m m 2 2 P a 2 a a I - 9 C - m I I g 2 . V3 EL ?L I P. m I N dI - m m vr.9 9 9 "i N .Z .s y< ea. The special linings considered in this group are those which are manufactured for an individual contract in many instances on or near to the construction site. The subsequent grouting filled the overbreak and at the same time acted as a partial seal against ingress of water into the tunnel (see Plate 33). smoothness of the bore depends upon the cutter head design rather than. The lining was erected with two semi-circular hoop bars in the tongue and groove joints and after pointing these joints the ring was grouted49 (see Plate 31). as the diameter increases the size of the segments become unmanageable and too heavy to lift without mechanical means. with the introduction of standard smooth bore modifications to the original lining in 191 1 linings and other alternatives in the late 1950's and 196OYs. The lining is not strictly an articulated lining although the toggles provide some flexibility at the joint (see Plate 29). the additional excavation required for manipulation of the segments into a ring would become uneconomic. This form of lining has a particular application in pressure tunnels where the depth of overburden is insufficient to take the internal hydrostatic pressure. expanded and smooth bore linings. . In the Mersey Tunnels the contractor employed a method of erection using longitudinal bars screwed to couplers within the previous ring. Alternatively special cylinders may be inserted at the joints to form 'pin joints' .(see Appendix 4). is available only in the small diameter range of 1. In these conditions this form of lining may be expanded into the ground and then grouted. A grouted form of expanded lining has recently been designed and used for the first time in a long length of tunnel for the Service Tunnel of the Stage 2 contract for the Channel ~"nnel". thus reducing erection time t o a minimum. The McAlpine lining has changed very little following However.0 m to 1. The Channel Tunnel lining was cast with four projecting pads on the back of each segment. In addition. The same method.3 m and competes mainly with the open cut and pipe jacking methods of construction. such as a former ring. Uncontrolled Copy. The Charcon Universal lining was developed in 1970 as an alternative to the bolted concrete.7 Expanded grouted concrete tunnel linings An experiment was carried out with the Don-Seg lining in the late 1950's whereby the lining was surrounded by two hoops of prestressing wire against which the lining was expanded37. The lining is erected on two segmental hoop bars which pass through the centre section of the ring and which are screwed together with toggles. to reduce manufacturing costs47. The linings for the two schemes are similar. is being used for the Dartford Tunnel (see Plate 32). The void between the clay and the outside of the lining was then grouted. The lining consists of three segments and requires no temporary support.Licensed copy from CIS: URS. the pads providing initial support against the excavation. The Rees Mini tunnel was introduced in 1969 as the first fully integrated tunnelling system in the United ~ i n ~ d o The m ~system ~ . and the discontinuities of the rock. on the cutting edge of the shield. .45749950 For the Mersey Kingsway Road ~ u n n e l s and l ~ for the Dartford Duplication Road Tunnel special articulated linings were designed for those sections in stable rock as alternatives to the more expensive cast iron linings. URS Infrastructure. In good cohesive ground the lining may be expanded in a similar way to tile Wedge Block lining but the expanded form has not yet been used to date. The three segment ring without a key is practically restricted to the small diameter range because as the thickness of the segments increases. as for a soft ground tunnel.this lining has not been used since 1961. with an increased number of bars. Where a tunnel is excavated by fullface tunnel boring machine in weak rock. 04/03/2015. The use o f 'Chocolate block' crack inducers permits controlled cracking in the event of deformations (see Plate 30). during erection. 5. the main difference being the width of the ring and therefore the weight of segments. using conventional tunnelling methods for the larger s i . Uncontrolled Copy. higher tolerances (say + 75 mm) should be allowed than for conventional tunnelling methods. There has been a large increase in the last few years in the number of firms carrying out pipe jacking work. particular thought needs t o be given to the condition of the embankment core. For pipe thrusting under existing railway embankments. Likewise there have been many occasions when the method has been used for small sections of long tunnels that pass below embankments or other structures whose owners have required these methods to be used. when the final level is critical as for a sewer. intermediate jacking stations.8 Pipe jacking with concrete pipes Licensed copy from CIS: URS. as an alternative t o open cut or heading methods either for direct economy or to reduce disturbance at the surface. In addition there is now a tendency for longer and larger contracts to be undertaken. in preference to tunnelling.5. One tendency has been t o attempt thrust boring too close to the surface.a ~ ~ .e. are designed to withstand the thrust forces and are therefore of a higher grade than would normally be required for a pipe at the same depth.0 m to 2. at which level drag of the ground rnay give rise to disturbance. Pipe jacking and thrust boring embrace a wide field of underground construction ranging from pipes of less than 150 m m diameter to large reinforced structures for bridge abutments. the loss of ground a t the face of the excavation may be highly dependent on the method and the workmanship. roads and railways where open cut methods would be particularly uneconomic. subways and underpasses. for long thrusts.are employed which are built into the lining and subsequently removed. be required. which may be poorly conlpacted. URS Infrastructure. to avoid settlement or interruption of the services (see Plate 34). . The insertion of polythene sheeting between the ground and the unit has recently been used successfully for a similar purpose. Back grouting may. double acting jacks rnay be installed thus enabling smaller shove forces to be used from the thrust pit or intermediate jacking stations. For the larger diameters and the longer lengths of thrust a lubricant may be necessary . One of the main criticisms of pipe jacking is the difficulty of keeping to the correct line and level. This method will reduce settlement associated with the radial movement of the ground for a grouted lining. mainly pipe jacking for the range of internal diameters from 1. The Pipe Jacking Association has recently been formed and has published a code of conduct binding on all members and which enforces standards54. long thrust. however. Though this has been improved with modern methods. One of the reasons for using pipe jacking under existing structures is that a rigid lining is provided immediately after excavation in the shape of a pipe with relatively little over excavation. A larger diameter internal section than necessary may be used with provision for a cast in-situ invert to accommodate the adjacent levels of the sewer.usually a bentonitelfly ash grout injected behind the shield. This section is confined t o the application of pipe jacking in preference to conventional tunnelling methods. Pipe jacking is suited to short lengths of tunnel of 100 n~to 150 m between jacking points and is often used for sections of pipe under embankments. on account of the need to keep traffic moving continuously. 04/03/2015.5 m. Pipe jacking is the process of pushing or jacking pipes through the ground from a thrust pit with the material at the face being excavated within a shield. which may have flexible joints. i. for the smaller diameter sewers. Waterproofing is obtained with the conventional watertight rubber rings in the flexible joints. however. Steering and adjustments for line and level may be made at the shield where.~ e s ~For ~ .which will cause unavoidable overbreak. In addition standard Conditions of Contract for pipe jacking and a design and specification bulletin have been drawn up for publication in conjunction with the Concrete Pipe Association 5 4 . using pipe jacking. The pipes. and which.1 Cast in-situ concrete tunnel linings The cast in-situ form of lining is economical where the whole length of the tunnel can be excavated and requires only ground support until the drive is complete. ground support may comprise one or more of the following: rock bolting. The choice of method of ground support prior to lining depends on the quality of the rock. In poor quality rock it may be necessary to cast the lining close behind the face and. Where water problems are likely during the construction of a tunnel one or more of several measures may be taken to reduce the ingress of water. with poorer quality rock. either by pumping from the surface using well points and/or by pumping from within the tunnel. For downhill drives a pilot tunnel in the invert will help to improve the working conditions for the main drive by taking the water away from the face.12but while each provides a first guide. This latter method includes: a) diverting the water behind the temporary lining in ducts to a drain below the invert. with pea gravel which can be subsequently grouted. or constituent materials. d) for larger flows from exposed fissures by forming channels and sealing with quick-set mortars. A pilot tunnel. These indices are briefly discussed in Chapter 8. e.the highest quality .however. the presence of water and the susceptibility to weatheringor swelling. to use a shield to limit overbeak and provide safety for the miners. or at axis level or in the invert of the main tunnel. URS Infrastructure. compared with a precast lining. c) the use of a mesh and plastic sheet behnd the permanent lining with drains on each side of the invert. For uphill drives water problems at the face will be reduced and thus this preferred method should b e used where practical. and steel arches and laggings. in certain circumstances may also improve the permanent conditions.no support is required before casting the primary lining. with or without steel mesh.g. the discontinuity characteristics. may be located either in the crown. These measures may include the injection of stabilising materials into the surrounding ground. ground freezing. with the main aim of improving the working conditions for the excavation and the lining of the tunnel. A main object of a pilot tunnel.6. CAST IN-SITU CONCRETE TUNNEL L I N I N G S ARID TEMPORARY GROUND SUPPORT Licensed copy from CIS: URS. In these instances some delays are bound to occur on account of interference between the removal of spoil and the delivery of mixed concrete. Uncontrolled Copy. Cast in-situ concrete tunnel linings have been used as permanent primary linings for rock tunnels since the turn of the century. well pointing and the use of compressed air. The principal factors affecting the behaviour of rock around a tunnel are: the structure of the rock.none dispenses with the need for careful assessment of the particular circumstances. The two main operations are thus separated with little delay caused by interference. in which case it may be necessary to consider the relative merits of a cast in-situ. when the permanent lining can be constructed. . b) placing a permeable layer behind the permanent lining.is usually that of locating the position of any likely problems of water inflow. 6. For weak rocks the ratio of the strength of the rock to overburden pressure at the depth of the tunnel should also be taken into account. constructed prior t o the driving of a large diameter tunnel. Alternatively small flows may be diverted. shotcrete.in severe cases. For strong intact rock . De-watering may be used to reduce the ingress of water. Several classification schemes have been proposed 7910911. 04/03/2015. when precast units are normally used t o give a good roadway t o the face. Alternative mixes such as the introduction of PFA t o replace the additional cement should be considered. the latter methods have been used with complete success although only for experimental sections in the United Kingdom. homogeneous and without serious cracking. while in the multi-unit shutter system the concrete is in various stages of curing along the length of the combined shutters. For large diameter tunnels. where a thick reinforced lining may be necessary. at depth. The minimum thickness of the arch concrete is normally 250 mm which is the least that can economically be placed. the concrete may be mixed at the surface and delivered by skip or agitator transit cars prior t o pumping or placing behind the shutter. In many tunnels the specification requires that the temporary arches are outside the nominal thickness of the lining and thus the theoretical minimum thickness is considerably greater and will be further increased by overbreak (see Fig. The whole lining may be cast in one operation or in two parts . An alternative method. 8). There are a number of alternative procedures which may be employed for casting the concrete linings. URS Infrastructure. In all cases. there may be difficulty in casting the crown and systematic grouting is usually therefore required at a later date t o fill any voids. While reinforcement may reduce the required thickness its use is seldom economic for small and medium diameter tunnels.is the casting of discontinuous lengths of tunnel with conventional shutters and s t o p ends. or on a continuous 24 hour cycle. for long tunnels this is not normally economic. Uncontrolled Copy. Alternatively. The individual shutters may be 6 t o 1 0 m long with two t o ten shutters used in the system to enable concreting to be carried out either on a one shift basis with stop-ends between each section. however.which is rarely used except for short lengths or large diameter tunnels.. The invert concreting may be cast using conventional invert shutters or with slipform methods. however.Licensed copy from CIS: URS. 04/03/2015. Shrinkage cracks may be reduced with this method but the construction takes longer. The method has been used t o concrete up t o 300 m of tunnel per week.tters on rails for erection for the next section of tunnel. which will allow the concreting t o be carried out without interference. The arch shutters may be of similar form t o those described above and the concreting process may be carried out while the tunnelling operation is in progress if the shutter is suitably designed. In weak to moderately strong rock an invert slab or a sub-invert slab may be cast. For short lengths of tunnel timber shuttering is normally used but for long tunnels the additional cost of collapsible steel shuttering is often warranted. When the whole lining is cast in one operation the excavation will normally have been completed for that drive. . a mix 25 per cent to 40 per cent stronger may be necessary to improve flowability and t o give a concrete which is sound. In the two shutter system one shutter leap-frogs while the other shutter is being concreted. The concrete may be delivered to the site ready mixed and pumped down the tunnel.the invert followed by the arch or vice-versa. the economics of a concrete with a higher compressive strength should be considered. The intermediate lengths are then cast after a period of time when the adjacent sections have cured. or some distance ahead of the concreting of the arch. When the invert is placed first i t may either be constructed immediately behind the excavation. often b y pneumatic placer. Telescopic forms may be used which can be collapsed and taken through the remaining sh. In the latter case provision can be made for the rails carrying the arch shutter. The minimum cover to reinforcement should be 5 0 to 75 mm and to steel arches 150 mm. or alternatively precast slabs may be laid as the excavation proceeds t o provide a lateral strut for the colliery arches and also a roadway for the removal of the excavated material. The invert shutter may be a separate unit to allow this t o be positioned before the arch shutter is moved into position. Comparatively low characteristic concrete strengths of 2 0 to 30 MN/mZ are usually specified but due to the method o f placing. 2 and Appendix 2. If several cartridges of resin with different setting times are used a controlled build up of load in the anchor can be obtained. Harecastle and Liverpool Loop and Link Tunnels.2 Rock bolting Rock bolts are used as a form of rock reinforcement. recent Briston sewers 61 . Details of a number of tunnels recently constructed with cast in-situ linings are given in Appendix 5. Two main groups are available which may be classified as passive dowels and actively-tensioned units o r mechanical bolts These bolts are discussed in more detail in Appendix 5 (see Plate 40). 04/03/2015. The resin bolts are normally grouted over their full length and tensioned or left untensioned. and hence the figures are subject to a wide annual variation. They may be made of mild or high tensile steel reinforcing bars or. The road tunnels include the Newport-Crindau ~unnels". The arch shutters are normally single shutters which are moved forward 12 t o 2 4 hours after each concreting operation and are designed t o allow continued access t o the tunnelling face. and the Edinburgh 0 u t f a 1 1 ~ ~Plate 6. Plate 36). Licensed copy from CIS: URS. The invert concrete is normally cast when the excavation and the arch concrete are complete and the cleaning out of the tunnel is in progress. when they are used as support t o the face and subsequently excavated. URS Infrastructure. In view of the small number of large diameter road and rail tunnels.is often carried out in advance of the invert construction when heavy support is required close to the face or before the excavation is complete. Cross Hands ~ u n n e l s ~ ' the . both of which were constructed using shields. they may be of wood. Such tunnels generally belong t o large single projects. The mechanical bolts are fixed at the base of a drilled hole with an expanding anchor. Plate 35). The BR rail tunnels include the woodheadS8. in the latter case rock movement which may develop at joints generates the tension in the bolt. and the Birmingham. the length of which will be designed to suit the type of rock. either t o cause jointed rock around an excavation t o behave monolithically and/or to provide the tension members of a composite structure. while. The anchor may take the form of a wedge which is forced into a slot thus enlarging the end of the bolt or an expanding sleeve which is tensioned by tightening the projecting end against a plate which bears against the rock. Uncontrolled Copy. 63764. These forms o f bolts may be subsequently grouted with the injection of cement grout or with the use of resin cartridges inserted with the bolt. Great Charles Street ~ u n n e l s ' ~(see . The diameters of the tunnels are generally larger than for tunnels lined in precast concrete. . This form is usually used for anchoring into the rock some distance from the excavation. The passive dowels may be inserted into a drilled hole and grouted if required or they may be driven into weak rock. and the Gibraltar-Hill Monmouth ~ u n n e l s ' ~(see .The concreting of the archin full or in part. Resin mixes are designed in relation to the temperature in the ground which controls setting time. A third form of rock bolt is the rock anchor which may take the form of a long cable grouted into a drilled hole. thus for a weak to moderately strong rock the anchor length will be considerably greater than for an extremely strong rock. The length and volumes of tunnels constructed during the last seven years and lined with cast in-situ concrete are discussed in Section 3. Alternatively the bolts may be grouted over only part of their length. those selected for discussion are up to 25 years old. the sewer and water tunnels discussed have been constructed since 1970. 39 shows cocreting in a small diameter tunnel. Rock bolts may be used on their own or in conjunction with steel arches. (see Plates 37 and 38). The water and sewer tunnels include the Foyers ~ r o j e c t ' ~the . mesh or sprayed concrete. Sprayed concrete has been used in the United Kingdom mainly for the repair and maintenance o f tunnels. In the United Kingdom rock bolts have been used in a number of tunnels as ground support. Other recent applications include sections of the B R Liverpool Loop railway. increasing interest in the technique both for tunnels and for coal mines 66.) While such materials have had wide application in the United Kingdom. Licensed copy from CIS: URS. It has seldom been used as a primary structural lining. however. Sprayed concrete may be used in conjunction with rock-bolting and wire niesh as a ground support. including repairs to existing tunnels by specialist contractors. The sprayed concrete layer may be reinforced with steel mesh or ordinary steel reinforcement according to the type of work. however.3 Sprayed concrete tunnel linings In the United Kingdom 'Gunite' is a trade name for sprayed mortar or concrete. In most instances for the construction of new tunnels it has been used as a method of ground support in areas of poor quality jointed rock. presence of water and type of drill. For new tunnels. T h s development is discussed in Appendix 5.67968 (see Appendix 5). design and pattern of the bolts 65 . was successfully sprayed to a thickness of about 100 nim. There is. (see Chapter 12).Pull out tests are often specified to help in the selection of the type. while sprayed concrete in tunnels is often called 'shotcrete'. In the United Kingdom a considerable annual quantity of sprayed concrete is applied to structures. 6. sections of the . especially brick tunnels. One of the first applications in this country in a tunnel was in the mid 1950's when remedial measures were necessary t o the cooling water tunnels for the Stockport Power Station. During the last few years sprayed concrete with steel or glass fibres has been introduced which gives a small increase in the con~pressivestrength and a large increase in the flexural strength when compared with ordinary sprayed concrete69. (In the United States the term 'shotcrete' is used for both sprayed concrete and sprayed mortar. URS Infrastructure. On a number of occasions it has been used as a permanent lining at openings and junctions between tunnels which otherwise would have been difficult to construct in other forms of lining. (see Appendix 2) and in the construction of new tunnels t o prevent degradation and weathering of the rock following excavation. where the quantities involved have been small and often not of a continuous nature the work has often been carried out by the tunnel contractor's labour. from the repairs of cooling water towers t o fire resisting steel columns. The application of a thin layer of sprayed concrete may completely or partially arrest the rock deformation while penetration of the joints and fissures will strengthen the loosened rock and help to develop a continuous stable arch. Uncontrolled Copy. There is a considerable variation in pull out loads not only between different rock types but also within each type of rock depending upon the physical and chemical conditions of the rock. The spraying of concrete is a skilled operation and the mix must be properly designed to suit the rock's condition and the plant involved. 04/03/2015. their use in tunnels has been limited by comparison with most other European countries and the United States. for secondary linings. A 380 m length of tunnel. In coal mines 9 0 per cent of the bolts used are now resin anchored. where there was evidence o f small rock falls. The use of large diameter bars should be avoided and the spacing of reinforcement should be arranged t o minimise interference with the concrete application. In the 1960's grouted or mechanically anchored bolts were generally used but more recently the use of resin bolts has greatly increased. the access tunnel to the Channel Tunnel works. The design of rock bolts is discussed in Chapter 8. prior to the casting o f an in-situ concrete lining. The distance between supports may be altered to suit the ground conditions. The use of arches is normally restricted to weak to strong and highly jointed rock tunnels. Plate 41 shows a sprayed concrete lined tunnel. In the United Kingdom open boarding is usually employed for the side walls with close boarding in the crown where spalling and loosening of the rock are likely to occur. which is laterally supported with spacers or struts with intermediate lagging7'. rib or frame. liner plates have been used behind the arches with pea gravel and grout to seal the void behind 6 1 (see Section 4. In most instances the laggings are primarily to prevent falls of the rock and thus act as a safety curtain for the miners. The loads from the rock are transferred either through timber blocks or packings directly to the arches at intervals around the periphery of the arch or alternatively through the laggings and thus to the arches. sprayed concrete will not be used as a primary lining but for ground support in difficult ground conditions. made up of a number of short intermittent lengths As part of the preliminary studies for the Kielder aqueduct at present under construction for the Northumbrian Water Authority an experimental tunnel has recently been constructed (see Appendix 6) in which sprayed concrete was used for a number of sections of tunnel7'. At the foot of the arch. In addition. 6. may be positioned behind the arches or between the flanges of the joist sections (see Plate 42). Uncontrolled Copy. except where a full circle rib is used. The close boarding will act as a form of temporary curtain. normally ofjoist cross section. normally from 1 metre centres down. For the main tunnel. For larger tunnels where pilots. steel invert struts may be used to control heaving of the base of the excavation. When close boarding is used the space behind may be filled with pea gravel or suitable selected spoil and grouted when required.3). The supports can be erected close to the face immediately after excavation. At the time of preparing this Report experiments are in progress investigating the use of long permeable bags filled with grout as a form of lagging between the arch and the ground73. heading or benches are used there is an advantage in designing the supports so that those removed from the temporary heading can be reused in the completed excavation. For the Liverpool Loop the running tunnels were constructed through Bunter Sandstone with roadheader machines and temporary steel arch supports where necessary. The total length with sprayed concrete was approximately 1 km. The different types of arches and the method of bolting are discussed in Appendix 5. Drainage pipes may be used to take the water into the invert if the void behind is grouted.4 Temporary arch and lagging supports The traditional method of temporary support in the United Kingdom over the last 25 years has been the steel arch. corrugated or perforated steel sheets. The base blocks may be cast into a concrete invert or sub base roadway to prevent lateral movement. . A cast in-situ lining was used for those lengths with temporary support while the unsupported sections were sprayed with 75 mm of concrete to prevent long term deterioration of the sandstone. In a few instances. iron bank bars or wire mesh. the loads are transferred to the rock through base blocks. A second application was made at a later date according to ground conditions.2. URS Infrastructure. or be strutted with steel beams if excessive side loads are anticipated or encountered. In either method the rock must be in physical contact to prevent excessive movement before appreciable load is transferred to the arches. For the CEGB Dinorwic Power Station a thin layer of sprayed concrete was applied behind the face immediately after excavation. diverting any water entering the tunnel. The use of sprayed concrete will prbbably increase during the next few years as the number of tunnels in moderately strong to strong rock is likely to increase. Licensed copy from CIS: URS. Arches may also be used in conjunction with rock bolting to improve the rock support or with shotcrete to prevent weathering. 04/03/2015. although they have been used on a small number of occasions in cohesive soils. which may be close or open boarded concrete or timber.Kielder experimental tunnel and the preliminary works for the CEGB Dinorwic Power Station. whlch may cause overstressing of the arch in bending. These laggings. The design of arches and laggings is discussed in Chapter 8. and the rock where visible. URS Infrastructure. In this system. The system requires a good fit between the components. It has. A form of temporary lining which has not been extensively used in the United Kingdom. The instrumentation of arches is briefly discussed in Section 7. steel perforated and corrugated sheets are used. A fuller description is contained in Appendix 5 . Regular inspections should be made of the arches. In soft ground or incompetent rock where subsidence at the surface should be rninirnised a lining erected close t o the face is generally preferred t o arch supports. and is expensive but may occasionally be justified in special circumstances. however. except for an experimental length. 04/03/2015.Licensed copy from CIS: URS. been used as ground support for short sections of tunnel through poor ground during construction of the NWA Kielder aqueduct. but which has been used for considerable lengths of tunnel on the continent is the Bernold system72 (see Plate 43). Uncontrolled Copy. acting partly as a support shutter for the cast in-situ concrete primary lining and partly as reinforcement to the full lining. to observe possible signs of overloading of the temporary s-upports and lateral movement of the arches. .5. and the deformations of. dusty and have large variations in temperature and humidity.6. MONITORING. This environment is likely to be wet. The instruments should be designed for the required accuracy and be simple to calibrate. the lining. The results of these researches help to improve the design methods for tunnel linings and to enable indications of the likely surface settlements to be established and thus the risk of damage to structures above. INSTRUMENTATION.7 .2 Deformation of the tunnel linings When a tunnel is constructed in soft ground or weak rock the applied loading around the ring will cause deformation of the lining until sufficient passive loading resistance at the sides of the tunnel is mobilised by compression and shear between the ground and the lining. where possible. If a rigid lining is used the deformation may be reduced. 7. 04/03/2015. and thus a better understanding of. The readings obtained from the instrument should where possible be analysed as the work proceeds. The number of sets of readings taken during this period should be as large as possible if large changes in the readings are anticipated. at the expense of bending moments developed in the lining. withstand the environment in which they will be installed. The instruments should thus be relatively cheap to enable a sufficient number to be installed. They should be sufficiently robust to withstand the curiosity of the tunnel labour force and covered to withstand shock. Uncontrolled Copy. The objectives of any research programme should be examined to establish the likely benefit to the understanding of the ground and the lining behaviour. The early instrumentation was limited mainly t o monitoring from w i t h the tunnel of the loads and stresses in the lining. Instruments should be designed t o be easily installed and. the consequential changes in porewater pressures. fixed or cast into the lining before the segments go to the tunnel face thus minimising delays to the tunnelling programme and.2 to 7. statutory authorities and universities. research organisations. the behaviour of the lining and of the ground during the construction of a tunnel and subsequently until long term equilibrium is reached between the ground and the lining. the pressures on.1 General Licensed copy from CIS: URS. The different forms of instrumentation and monitoring of tunnels are discussed in Sections 7. The programme should take into account that the major portion of the monitoring will be over a relatively short period of hours or days when the tunnel is constructed past the point of observation. if possible. RESEARCH AND DEVELOPMENT 7. more recently. The instrumentation and monitoring of tunnel linings and the ground in the vicinity of a tunnel are carried out to provide more detailed information on. The relaxation of the . The funds available for research of tunnels are normally limited and much of the equipment non-recoverable. readings should be taken remotely from the location of the instruments. thus enabling errors in the instruments or the reading techniques to be found during the course of the works rather than at a later date. The monitoring has been carried out by consulting engineers. Movements within the ground as a tunnel is constructed have been monitored on a number of occasions in the last 10 to 15 years and. Instruments installed in the lining should be designed to cause as little modification to the structural performance of the lining as possible otherwise they will be measuring conditions different from those of the standard lining. URS Infrastructure. in relation to an articulated lining. For the design of a lining an estimate of the likely magnitude of any deformation is a fundamental requirement. The output should therefore be designed to suit the results required for the final objectives and not obscured by a large quantity of data that may never be used. dirty. The instrumentation and monitoring of tunnels and the fullscale laboratory testing of linings have been carried out in the United Kingdom for many years. All instruments should be reliable and constructed to. a tunnel lining may be subjected t o further deformations if a tunnel is constructed adjacent to it.3 m linings. Two cases of an increase in the vertical diameter have been monitored in the United Kingdom.Licensed copy from CIS: URS. and the deforn~ationsof. 04/03/2015. Uncontrolled Copy. When these face support techniques are used the deformations will be considerably smaller. In many instances particularly with expanded for example. Deformations of tunnel linings have been recorded subsequently for a number of tunnels in the United Kingdom. have been recorded.5 per cent. considerably larger deformations than for tunnels in stiff clay have been recorded in a number of instances. URS Infrastructure. the deformations may be negligible. although with compressed air some further deformations will occur when the air is turned off. The extent o f the deformations wili be dependent upon the state of stress in the ground at the time the lining is erected.1 per cent and 0. These instances were either tunnels constructed in compressed air or in soft clays or silts and in all cases t h e deformation reversed with time with increases in the horizontal diameter. two rings were monitored to determine the stresses in. It is probable that the compressed air pressure which is normally based on the head of water at the invert reduced the overburden loading on the lining thus allowing greater horizontal pressure to develop.015 per cent of the diameter. the coefficient of earth pressure at rest < 1) and thus the lining will tend to deform to an elliptical shape with the major axis horizontal. deformations of small diameter tunnels of 100 mm. . the lining. with the exception of soft clays and silts.4 per cent (say 5 to 2 0 mm for a 5 m diameter tunnel) over a period of several years and no instances of a reduction in the horizontal diameter were recorded for tunnels in the United Kingdom. In several cases in silt. In general the horizontal diameter increases linearly when plotted on a log-time scale and for most soft ground materials. and workmanship. These data showed that for tunnels in London Clay (where KO > 1) the horizontal diameter generally increased by between 0.5 m internal diameter TWA Southern main was constructed recently in London Clay at depths up to 50 m with two full face tunnelling machines. as discussed in Chapter 10.5 m m . For tunnels in soft clay or silt. In certain very soft clays. the deformation after six years was only 1. Much of the recorded deformation of grouted linings may be attributable to grouting delays and t o incomplete grouting of the crown. Several of these tunnels have been constructed in free air or without other techniques to hold up the face. For the Heathrow Cargo internal diameter tunnel was constructed at 7 m cover with an expanded lining. The 2. or 0. In addition t o the deformations accompanying the build up of the ground pressures. the tunnel. the type o f soil or rock. which was constructed with compressed air and lined with a grouted grey iron lining. mation was not apparent. gave a small number of instances for which the vertical diameter increased and the horizontal diameter decreased.where a 10. The Wedge Block lining is expanded in the crown and this may have lead to mobilising of the lateral forces at a quicker rate than the vertical forces. Monitoring of the deformations of the lining showed that there was a slight increase in the vertical diameter with time 75. rarely exceeds 0. collected together the available data on the deformation of tunnel linings. In these two rings increases in the vertical diameter of 1 mm and 8 mm were recorded. ground reduces the stress in the lining which is the theory behind many of the present design methods. a rigid lining may be necessary to prevent the collapse of the lining. If good tunnelling practice is employed this will be considerably less for tunnels in weak rock. In this particular case the subsequent reversal of the defor-. passes over or below it or if an excavation is carried out adjacent t o it. or over 5 per cent of the diameter. In the majority of soft ground tunnels the lateral pressure on the lining is lower than the vertical pressure (KO. The second example was the construction in sand of the outfall tunnel for the CEGB Sizewell Power Station in the early 1 9 6 0 ' s ~ ~In. If the tunnels cross at a skew angle larger movements will occur but these will normally be acceptable. in stiff t o dense materials with good tunnelling construction practice.0 m diameter tunnels were in the range of 4 mm to 7 mm. but this is generally over a restricted length and special precautions may have to be taken during the construction.5). where grouted. Several tunnels in London Clay have crossed at right angles or at a skew with distances between the tunnels of less than a metre. If the two tunnels are to be constructed under the same scheme the lower tunnel should generally be built first. The lining may be tie braced across the diameter or the diagonal to restrict the deformation. embedding the cutting edge of the shield or keeping the face boxed when excavation is not being carried out may be necessary. which are similar to the deformation of a typical lining following erection. Where tunnels cross at right angles relatively little movement will occur if the tunnels are located with a clearance between them equivalent to one diameter of the larger tunnel. the extent of . This analysis should take into account the tunnelling method and whether special techniques are to be employed. In these conditions. and are dependent upon. the lateral forces on the lining and the extent t o which these will be relieved during the construction of the adjacent tunnel should be examined. In these conditions measures may be required within the existing tunnel to reduce the build up of excessive stresses within the lining (see Section 19.Licensed copy from CIS: URS.1. The deformations of the lining and the settlement of the tunnel have generally been restricted to the range of 10 mm t o 25 mm when special precautions have been taken. discusses a number of case histories where measurements have been taken of the deformation of a tunnel lining during the construction of an adjacent tunnel. If a tunnel lining is fairly flexible unsymmetrical distortion of the lining will occur. In special cases. In general. For tunnels in rock the state of stress before and after the construction of the tunnels should be analysed before minimum distance between adjacent tunnels can be assessed. such measures should be carried out with caution and under strict control. Tunnels have been constructed closer but each circumstance required individual analysis. 7.77778 779. the method of tunnelling should be reviewed to restrict the ground movements. Rings. for the construction of a crossover the tunnels may approach to within half a metre. with the maximum distortion on the side adjacent to the new tunnel on account of the relaxation of the lateral pressure. For example. In the cases illustrated.3 Sub-surface movements and porewater pressure changes Ground surface movements which develop during the construction of a tunnel in soft ground and in weak rock are discussed in Section 7.80?8 l. such as large diameter tunnels. These precautions would include driving the section of tunnel with a minimum time lapse before the lining takes the ground load. For tunnels in weak materials. These surface movements originate from. the deformations at 2 m from the periphery of a number of 4. in particular. tunnels may be constructed with relatively little deformation to the existing tunnel with a clearance between the tunnels equivalent to half a diameter of the tunnels. should be grouted immediately after erection and if possible the face should not be stopped for a long duration immediately below the point of the crossing. Uncontrolled Copy.4. In one or two cases with a bolted lining the bolts have been removed in the circumferential joints and slackened in the longitudinal joints to form an articulated lining which reduced the tensile stresses in the lining. 04/03/2015. however. the movement is less than half the movement at the periphery 24943. Fig. URS Infrastructure. However. Details of tunnels where deformations have been measured in the United Kingdom are given in Appendix 6 . 9 shows that the lateral movement of the ground during the construction of a tunnel usually falls off rapidly with distance from the tunnel periphery and that at a distance equivalent to half the diameter. adjacent tunnels should generally not be closer than one diameter. However the individual conditions should be assessed. When an excavation is carried out adjacent to or above an existing tunnel the pressure on the lining is likely to be reduced to a value that may affect the stability of the lining. URS Infrastructure. In these earlier schemes the ground movements were measured at frequent intervals.3. Horizontal movements have normally been measured either with an inclinometer lowered down tubes grouted into boreholes or with the use of a vertical plumb bob. In the inclinometer tube system horizontal readings are talken over the full length of the tubing. are given in Fig. In both cases the movement towards the tunnel was first detected when the shield was approximately one diameter from the point o f observation and 4 0 per cent of the final movement occurred before the cutting edge passed the point. coupled with the use of a reed switch. at Netherton Road and Particulars of these two drives are given in Table 7 and plots of the ground movements against at Brixton distance for both the tunnels. Uncontrolled Copy. 04/03/2015. For the Netherton Road tunnel.1 m internal diameter LTE Victoria Line running tunnels. 9 . The monitoring of horizontal and vertical ground movements as a tunnel is constructed has been carried out o n a number of occasions though until recently only for tunnels in cohesive materials. for example every half hour.5 mm a n d was reached when the tail of the shield was 1 or 2 m beyond the point of observation. which was constructed at a rate approximately twice that of the Brixton tunnel the movement. approximately 0. .1 Horizontal sub-surface movements transverse to tunnels Horizontal movements transverse to the tunnel were taken around the 4. With the vertical plumb bob and extensometer systems regular readings a t selected points and at frequent intervals can be made.45 m from the periphery of the excavation. taped t o the outside of the tubes. while vertical movements are taken at selected points with a separate instrument.5 mm and there was no sign of the clay against the skin of the shield. which enabled any changes in the rates of movement over short periods t o be identified. to enable t h e movement at any depth to be calculated. 24777. was 11. drilled either: a) from adjacent tunnels into the ground in the vicinity of the approaching tunnel in which the horizontal radial movements were monitored as the shield approached and passed the point o f observation. In the earlier schemes readings were taken in horizontal boreholes.45 m from the periphery of the excavation. a t axis level approximately 0. In this system several boreholes are normally drilled in the vicinity of the future tunnel to give an indication of the extent of the movement caused by the tunnelling. However.. The final movement. or with vertical extensometers fixed or grouted into the ground at different depths. 7. after an initial sudden movement at the cutting edge. The vertical ground movements have either been measured at magnetic rings. was 12. Licensed copy from CIS: URS. on the side of the shield on which the measurements were taken. or b) from a chamber ahead of the approaching tunnel where the boreholes were in the line of the tunnel and readings taken of the horizontal axial movements as the face approached the point of observation. These ground movements are discussed in this section with additional data in Appendix 6. with the more complicated measuring system for horizontal movements.he movement of the ground in the vicinity of the tunnel. only one or two sets of readings can normally be obtained each day unless readings are taken round the clock. continued at a constant rate over the length of the shield at which stage 9 0 per cent of the final movement had occurred. Recent measurements have been taken mainly in vertical boreholes drilled from the surface with horizontal and vertical measurements of ground movements taken in the vicinity of the approaching tunnel. The bead. 5 2 .5 12.0 Regents park8 34 20 4. 9(a) and the particulars of the tunnels given in Table 7.1 0.4 11.5 m m and was reached when the tail of the shield was a diameter beyond the point of observation. Uncontrolled Copy.00 hours and 20.7 0. for the ~ r i x t o extension.1 3. 9(c)).3 6 LTE Licensed copy from CIS: URS.1 1. partly compensating for the slower rate during the stoppage.5 2 .5 mm and the movement 0. The tunnel at Netherton Road was 5 0 per cent deeper than the Brixton tunnel and with a slightly larger bead. those for the deeper tunnel constructed at a faster rate at Netherton ~ o a were n~~ The results are plotted on Fig.1 0. The rate of movement before.5 1. with the expanded concrete lined tunnel causing smaller inward movements than the grouted cast iron linings.O 4.8 3. The readings a t or near axis level for the three tunnels are plotted on Fig.5 2 . 9(a). as shown in Fig. during and following the stoppage are given in Table 8 which illustrates that the rate of movement when the tunnel was stopped was between 3 0 per cent and 60 per cent of that when the tunnel drive was in progress. Brixton77 For the Brixton tunnel with the slower rate of progress the inward movement of the clay at the periphery of the excavation was restricted by the shield skin thus reducing the rate of movement of the ground behind. However. was 12.7 8 .8 Netherton ~ o a d ~2 4 ~ 4. is such that F(T) = 1 when T = 0 and F(T) = 0 when T = 1). Similarly the average rates of movement over t h e shield were several times smaller than the peak values (which could satisfy a time related 'elastic' modulus.TABLE 7 Horizontal sub-surface ground movements transverse to the tunnel Tunnel Movement (6) mrn at distance (H) m from the tunnel periphery 6 H 6 H Depth m Diameter m H 15 4. the two sets of readings gave very similar final results. The final movement. therefore the inward movement would be expected to be greater. 04/03/2015. Just before the shield tail passed the point of observation the rate of movement accelerated until the ring had been erected and grouted. Following the stoppage the rate of movement increased slightly.O 7.O Green 30 4. close t o the periphery of the excavation. For the points further away d ~lower ~ than those from the tunnel. approximately 0.F(T)) where 4 = constant and F(T).45 m from the periphery of the excavation.1 1. .5 5 . such as E = El + 4 (1 .5 2.O 4.5 m from the tunnel and fall into the same pattern as those for the Victoria Line tunnels. URS Infrastructure.0 Seven Sisters2 4 (enlargement) 20 6.00 hours and the face left unsupported. equivalent to only 5 0 per cent of the total movement. This graph is particularly interesting as the tunnel drive was stopped for two hours between 18. The bead on the shield was 9. function of time.45 6.1 6. During the construction of the LTE Fleet Line horizontal movements transverse to the tunnel were measured with inclinometers around one tunnel at Green ~ a r k and ~ two ~ 3tunnels ~ ~ at Regents park8 l .O 2.1 4.45 m from the tunnel was restricted over the length o f the shield to 5 to 6 mm. For the Netherton Road tunnel it is possible to plot the movement with time (see Fig. The readings were taken a minimum distance of 1. 9(b). 45 m from tunnel 0.006 0. Table 8 shows how the rate of movement considerably reduces during relatively short stoppages of the drive.06 0. The results.TABLE 8 LTE Victoria Line Netherton Road -. although there was a larger variation between the readings. . The two tunnels in silt.7). URS Infrastructure.017 0.5 ni from the periphery of the excavation. Radial Movement For the Heathrow Cargo ~ u n n e lwhich ~ ~ . Horizontal movements have been recorded for a few schemes in different strata but on account of the small number of readings it is difficult to draw any conclusions. Uncontrolled Copy.03 0.035 0. The results of the relatively small number of tunnels in London Clay for which radial horizontal movements have been recorded show how the ground movements increase towards the tunnel periphery to a maximum of between 15 m m and 2 0 mm.035 0.increases. is a large diameter tunnel close t o the surface. show larger movements towards the tunnel than the tunnels in stiff clays. o n account of the small number of schemes involved. 9(a) but the measures taken to restrict the settlenlent at the surface. The main results are shown in Table 9 .0 m from tunnel 0. This value falls between the two graphs on Fig.instantaneous rates of ground movement RATES OF GROUND MOVEMENT Average over length of shield mm/min Immediately prior to stoppage mm/min During stoppage mm/min Resumption of tunnelling mmlmin 0. discussed in Section 7. but it is to be expected that movement will increase as the overload factor .02 0. Similar readings were also obtained in the fissured Lower Chalk. Although the shallower tunnel at Regents Park gave a smaller movement there is no correlation of movement with depth.3. The inward movement for an expanded lining is lower than that for a grouted cast iron lining.02 0. the inward movement was 7. will have influenced and reduced the values.01 6 2. having a low depth t o diameter ratio (0. 04/03/2015. as would be expected.004 Axial Movement - Licensed copy from CIS: URS.085 0.3.the ratio of the overburden pressure at the tunnel to the unconfined compressive stress . for the tunnel in laminated clay were similar to those for the over-consolidated stiff London Clay. The effects of rate of progress and of the depth of the tunnel are not apparent from the small number of readings.however.6 mm at 1. and the movement developed over some 8 m equivalent to 20 hours. while at Netherton Road they were 11.9 0. For the Brixton tunnel the average rate of advance was approximately 0.1 1.0 1. on account of the dome shape of the profile would be nearer 14 mm than the maximum of 18 mm which is therefore lower than the estimated radial movement at the periphery of the excavation.o 13.5 Kings ~ ~ Tyneside (llg3 Willington Gut Licensed copy from CIS: URS.5 mm and 10 mm respectively. At Netherton Road the movements developed according t o the distance from the face.3 13.5 1. The values for the radial movements for these two tunnels at axis level. The axial movements commenced 1 t o 1% diameters ahead of the face but 90 per cent of the movement occurred within one diameter of the face and 7 0 per cent within half a diameter of the face.5 mm compared with 16. was dome shaped with the movement on the centreline (18 mm) being 2% to 3 times that at the periphery of the excavation (6.9 4 .1 4.065 mm/min.2 Horizontal movements parallel to the centreline of tunnels Measurements were taken of the axial movement of the ground towards the face of an advancing tunnel on the LTE Victoria Line at Brixton 77. ~ .3 m outside the excavation was little more than 1 mm.055 and 0. Uncontrolled Copy.TABLE 9 Horizontal ground movements transverse to tunnels in strata other than London Clay Type of strata Measured Movement mm Distance from tunnel m 5 -0 1.0 2 . At Brixton at 0.5 mm.5 New Cross (21g6 Gravel 10.5 2 -0 12. one on the periphery of the excavation and one 0.O 0. are similar for the same distance from the periphery of the excavation.02 1 mm/min and the peak rates over the last metre were 0.3 10.O 5 . URS Infrastructure. one on the centreline.8 6.025 and 0. The locations and the measured movements are shown on Fig.0 10.4 m per hour.5 mm).3.78 and at Netherton ~ o a dAt~ Brixton. three points were instrumented in the horizontal plane of the axis of the tunnel. 04/03/2015.O 7.3. The movement 0. however. and the axial movements discussed above.O 0-4 0. as would be expected.0 7.4 0. The effects of this face movement and the radial movement are discussed in Section 7. Depth to axis of tunnel m Diameter of tunnel m Scheme Notes: n Siltn ~ Silt ~ (1) Tunnel constructed with compressed air.3 m outside the tunnel excavation. 10(a).O 13. The total movement immediately prior to the shield arriving at the point of observation was 12. 7.4.5 mm at Brixton.4 4.3 ~ ~ n e s i d e ~ ~ Laminated Hebburn Clay 7.45 m from the tunnel both readings were 12. (2) Tunnel constructed with bentonite shield.0 4.1.O 3 . The average rates of ground movement for the two tunnels were 0. The pattern of movement.5 3 -6 chinnor8' Lower Chalk 8 . The rates of movement for the two tunnels were therefore approximately similar although the rate of advance varied by a factor of two.0 6 . . The average face movement at Brixton. discussed in Section 7. with 60 per cent of the total movement occurring within 2 m and 40 per cent within one metre of the face. ~ ~ . 11 (c). from a manhole. for b o t h the laminated clay and the stiffer stony clay. Uncontrolled Copy. The results have therefore shown little axial the overall axial movement 1.5 m or more outside the periphery of the excavation. ground movements were measured at three cross-sections. The anchor measurements showed that t h e movement towards t h e face commenced 1% diameters from the shield and that 8 0 per cent of the movement occurred within one diameter of the face and more than 50 per cent within half a diameter of t h e face. URS Infrastructure. laminated clay. In over consolidated clays the three sets of observations taken to date have shown a slight heave of the points near the crown. in time and distance.Licensed copy from CIS: URS. and increase non-linearly with depth with a maximum just above the tunnel crown. Measurements were also made at_the face with dial gauges during weekends to measure the rate of movement of the face. The results again showed that t h e peak movement into the face was similar t o the maximum radial movement 8 4 . the closer the point of observation t o the tunnel the sooner. o f 1 t o 3 mm. t h e movements at depth are lower than those at the surface as illustrated in Fig. occurring 1 0 m t o 3 0 m behind the face of the shield as indicated on Fig. one with a cover of 32 m . When considering a vertical section on the tunnel centreline. was w h constructed ich with 28 rn of cover with a hand shield a n d lined with a bolted grouted cast iron lining. to measure the face movement in the laminated clay. This latter reading could therefore be disregarded for general interpretation. boulder clay. 1 l(a). movements in the United Kingdom were taken around the Heathrow Cargo ~ u n n e in subsequently. 79980 At ebbu urn^^ the inclinometers on the centreline were extended into the area of the future tunnel and a maximum axial movement towards the face of 2 mm at axis level was recorded. Table 1 0 gives data o n the individual tunnels and a summary of the recorded movements. The increase in the movement with depth is illustrated in Fig. Following the passing of the shield t h e movement of the tube above the tunnel decreased with little final displacement. These tubes. but restricted t o a narrower width. The average surface settlements and the measured average vertical ground movements close to the tunnel are given in Table 1 0 together with the estimated movement at the periphery of the excavation based on these measured movements. 1l(b). The method of construction of t h e tunnel and the type of lining will influence the extent and magnitude o f the rnovement. measurements have been taken for other tunnels in London Clay. The variation of ground movements with depth off the centreline of the tunnel are of a similar form but of lower magnitude. the total movement will be completed. For t h e LTE Fleet Line at Green ~ a r k ~ ~ .3 Vertical ground movements Probably the first systematic recordings of sub-surface vertical ground 1 London ~ ~ Clay in 1967.3. The general variation of ground movements with depth on the centreline of the tunnel are shown in Fig. when unboxed. The movements below ground level are larger than those at the surface. 04/03/2015. The recorded axial movements at T R R L experimental tunnel at Chinnor in Lower Chalk were generally only 2 m m t o 3 m m as the face approached and passed the point of observation but in one borehole on the centreline the movement immediately above the crown later increased to 7 mm probably due to the displacement of chalk blocks8'. The results of the face intrusion measurements at the weekends showed a linear relation with time. 10(b)).5 m outside movement. 1 l(a). Further from the shield. A number of readings o f the movement parallel t o a tunnel have been taken using inclinometer tubes. The readings at Regents Park were very small. gravel and Lower Chalk. however. between the ground surface and the crown of the tunnel. silty clay. Similar measurements were taken at Regents parkg1 above two tunnels. 7. with a similar although more peaked dome shape to that at Brixton (see Fig. have not normally extended into the area of the face and have therefore only measured the axial movement a t 1. During the construction of a sewer tunnel at ebbu urn^^ in County Durham horizontal anchors were positioned in front of the advancing tunnel. I n the instrumentation of the Fleet Line at Green Park the tunnel a t axis level was less than 3 mm with no significant relation between the direction or the magnitude of the movement and the position of the tunnel. 4mand 15 m arch width 8 . .O ~ ~ n e s i d e ~ ~ Clay Hebburn Bolted Concrete 7.75 LTE ~ e ~ e n t s ~ London Park Clay Expanded Concrete 34 20 4.5 (at 3 m) - 1.Licensed copy from CIS: URS.O (1.1 6.9 12 16 ~yneside~~ WiUington Gut Silt Bolted Concrete 13. Uncontrolled Copy TABLE 10 Vertical ground movements Ground formation Tunnel Depth axis External diameter Surface movement (m) (m) A (mm) Movement 1.4 4.9 11 14 (at 900 mm) 15 1.9 3.O 7.3 A 18 B 28 C 45 32 40 50 - Liverpool87 Loop Boulder Clay Cast Iron & Concrete 40 45 - - chinnor8' Lower Chalk Arches 13 20 2.1 ~eathrow~~ Cargo Tunnel London Clay Expanded Concrete LTE ~ Cross ~Gravels ~ Bolted Cast Iron LTE Park e w 7.1 5.8) - For the WillingtonGut Contract the borehole on the centreline was partly grouted as the face approached.5 23 27.5 m above crown (mm) Est.O 8 . URS Infrastructure. The movements varied considerably with time.4 10 10. movement at tunnel Ratio B (mm) BI A London Clay Bolted Cast Iron 30 4.1 to 1.5 16 16 22 2.0 min to crown 11.5 7 11.O 5 .1 16 23 3. The results quoted above are for a borehole just outside the line of the tunnel.4 4.5 2 .5 - Note: P cn Lining 6.1 21. (B) 51 days and (C) 159 days after the shield passed the point of observation. The results are for (A) 23 days.3 2 . 04/03/2015.1 4. is difficult to interpret from the three results. which was constructed at a shallower depth than the LTE Fleet Line tunnels. They also show that. which are plotted on Fig. was in laminated clay. 12(c). in the boulder clay above a 14 m wide horseshoe concourse tunnel.0055-0. 12(a). which was constructed in several stages with a cover of only 6 metres caused settlement at the surface of 4 0 mm to 6 0 mm over the width of the tunnel. 12(a) is not apparent here. On account of the measures taken t o restrict the ground movements. In consequence the maximum vertical ground movement occurred some 3 m above the crown of the tunnel. The maximum rate of ground movement was 0.face of the tunnel was boxed and face rams used to keep a constant force o n the face when the material was not being excavated in the shield compartments. for tunnels nearer the surface. URS Infrastructure. which was constructed with the bentonite tunnelling machine in water bearing gravels. Steepening of the curve above the shield as illustrated in Fig. The tunnel. These measures reduced the ground movements above the tunnel. shows another variation from the common pattern of movement. The LTE running tunnel at New crossg6. 12(a) which gives the vertical ground movement plotted against the distance from the tunnel. gelled in the surrounding ground and thus reduced the ground movements immediately above the tunnel. The relation between movements and depth-todiameter ratios. 04/03/2015. The bentonite.3. Heave of the invert o n the centreline of the tunnel was also measured. larger vertical ground movements occur near the crown than for deeper tunnels if the same construction methods are used. the deeper expanded concrete lined tunnel giving the smallest vertical ground movement and the shallower tunnel between the other two curves.9 m above the tunnel occurred as the shield was embedded into the ground immediately below the point of observation which was followed by an acceleration of the downward vertical ground movement.89 For the BR Liverpool ~ o oreadings ~ ~ were ~ taken . This tunnel. The three curves are all of the same form with a bolted cast iron lining showing the largest vertical ground movement near the tunnel. The Heathrow Cargo Tunnel was constructed in London Clay with an expanded concrete lining using techniques to minimise ~ e t t l e m e n tThe ~ ~ . These two tunnels were constructed with hand shields and lined with expanded concrete linings. The shield was shoved into the face for the full depth of a ring and the erection of the next ring commenced before the excavation in the face.1 that there is less vertical ground movement around a tunnel with an expanded lining than with a bolted grouted lining. The ground movements were however of a similar form although the ratio of the settlement at the tunnel t o that at the surface was reduced. These readings are for a particular method and .Licensed copy from CIS: URS. These results are shown on Fig. Predictions from these three sets of readings should be made with caution but they generally confirm the conclusion in Section 7. the curve is of a different form to the Fleet Line curves. The vertical ground movements for these three tunnels are shown in Fig.0070 mm/min which compared well with the laboratory extrusion tests88 but which is lower than the horizontal movements (radial and axial) for the Victoria Line. 12(a). and the related movement at the surface 85.0035 mm/min which again compared well with the laboratory extrusion tests.5 mm at 0. Uncontrolled Copy. Heave of the point 0.'The effects of the measures are illustrated by Fig. The maximum rate of ground movement for the Green Park tunnel was 0. this was estimated to be 7. The ground movements for the NWA Tyneside tunnel at ebbu urn^^ are also plotted on Fig. which was used t o support and stabilise the face. 12(b) where the development of the ground movements is plotted. and the other with a cover of 18 m. At TRRL experimental tunnel at Chinnor which was constructed at a shallow depth in Lower Chalk the movement was affected by the reaction ring behind the shield (see Appendix 6) and by the fissured state of the chalk.5 m from the periphery of the excavation. The data in Table 1 0 show the extent of the vertical ground movement immediately above the crown of the tunnel. . with ideal tunnelling conditions and methods of construction. In many soils these changes in the stress pattern are of benefit to the construction and allow the strength of the ground to be mobilised thus reducing the short term and in some cases the long term loading on the lining. 7.4.5 m head of water following the passing of the shield. the geometry and the depth of the tunnel. In some soils special measures such as compressed air. Piezometers were also installed in the vicinity of the second tunnel from both the surface and from within the tunnel. the rate of progress of the tunnel and the distance from the face to the structural lining when the ground is only partially supported. before falling dramatically t o 5 m as the shield passed below. The effect of many of these items is difficult to assess on account of the small number of case histories available and the overlapping of the contributory factors. ground water conditions. 7. the movements will be related to the ground type and this is generally the approach used when discussing settlement. Recently porewater pressure piezometers were installed in the vicinity of a sewer tunnel being constructed in silt at the NWA Tyneside Willington Gut contract 83. Licensed copy from CIS: URS. During the subsequent 12 months the pressure recovered to approximately 13 m.3. be kept t o a minimum to avoid damage to the structures above. although often insignificant. be specified by the designer to meet these requirements. such movements are those associated with the construction of the tunnel and do not take into account large movements associated with loss of ground or falls at the face which may be accompanied by considerable damage to structures above. These showed that the pressures rose by 1. chemical consolidation or de-watering may be necessary to reduce the ground movements. There are many factors which affect the development of ground movements: these include the type of strata and the soil parameters. In uniform soil. Uncontrolled Copy. however. When considering damage to structures above a tunnel the differential or relative movement across the building or between sections of the building is important rather than the absolute magnitude of the settlement. (see Appendix 6). to 19 m head of water. URS Infrastructure. in many cases. in all soft ground and in some weak rock tunnels on account of the changes in the ground stresses and porewater pressures in the vicinity of the excavation. The results of the instrumentation of vertical ground movements give some indication of the variation of movement with depth from the surface.sequence of construction and therefore cannot generally be used for prediction for other tunnels. The monitoring of the pressure during the construction of the tunnel showed that as the shield approached the pressure rose by 2 m. but on account of the relatively small number of schemes involved in different strata it is difficult to draw definite conclusions. The designer of a tunnel will be required to assess the magnitude of the surface movements which would be considered tolerable and acceptable to the structures and thus the method of construction will.4 Surface settlement The process of driving a tunnel will cause some surface settlement.4 Porewater pressure changes: As part of the instrumentation of the LTE Fleet Line at Regents Park 8 1 a piezometer was installed 1. However. It is expected that in this case the pressures probably went negative as the shield passed. 04/03/2015. however. The surface settlements and deformation below ground level must. though they could not be measured with the type of piezometers installed. the method of excavation and the type of lining used for the tunnel.5 m above the tunnel on the centreline prior to its construction (see Appendix 6). As the tunnel was at an axis level 14 m above the first tunnel the pressures were considerably lower and the results not so conclusive. The contribution of the horizontal and vertical ground movements to the surface settlement is discussed in Section 7. for soft ground tunnels the percentages fall into the ranges given in Table 11. Attewell and ~ a r m e r discussed ~l two cases of settlement in clay. or a) on studs or tubes cast into concrete blocks. mainly in over-consolidated London Clay. 13(b) shows a typical profile of the development of settlement as t h e face of the tunnel advances towards the point of observation.a slight heave has been detected ahead of the settlement trough 79. In most strata the ground movements develop over a relatively short period and are therefore not affected by the general ground movements due t o varying climate and ground conditions. For example. pavements and road surfaces.4. In the first case the settlement profile fitted the probability curve accurately b u t in the second case. in London Clay. the trough was elongated with the near maximum settlement extending over a larger proportion of the settlement trough probably due to the overrelated the extent of the settlement trough to a consolidated state o f the London Clay.80. Uncontrolled Copy. Additional movement may occur when the compressed air is removed from a tunnel constructed using this method. which was confirmed by stud points along the pavement adjacent to the park.which extend several feet below the ground surface and which are positioned at set points along the centreline of the tunnel or transversely t o the tunnel. Under t h e built up area. vary considerably. areas of unconsolidated material or voids below the structures. and schrnidt90 have proposed a statistical model t o express the settlement trough which approximates to t h e shape of an error function or probability curve with the maximum settlement value above the tunnel centreline. URS Infrastructure. The discrepancy between these readings may be explained by variation in the strength of the London Clay and t h e strata above. In a number of the tunnels. however. A shield-driven tunnel advanced in a straight line a t a uniform rate in uniform ground is most likely t o fit such simplified predictions of settlement. within the accuracy of the instruments and operators. often by a factor of two or three and the width o f the settlement trough is therefore ill-defined. (b) on studs positioned on structures. . Deere et a17 and function of the depth and the diameter which is shown in Fig. however. the surface movements varied from 6 to 18 mm but were generally restricted to 6 to 1 2 mm. 04/03/2015. in a horizontally bedded ground. The amount of settlement which occurs ahead of the shield. The width of the trough is largely dependent upon the depth of the tunnel below ground level and the type of strata. the results of the settlement profile readings l Park showed a maximum settlement reading above the centreline of each above the LTE Fleet ~ i n e at~ Regents o f t h e tunnels o f 5 t o 7 mm. is symmetrical about the centreline of the tunnel. 13(a). The results of readings on structures. The results of the readings in open areas generally give consistent results. In general. Fig. In both cases reference datum points are positioned well outside the likely trough of movement. including water table level and vegetation. for which smooth settlement trough curves can be drawn. preferably in openSareas. pavement and road surfaces situated above the line of the tunnel which are convenient for surface levelling.1 Development of settlement profile and trough: The settlement caused by tunnelling is a troughlike depression which. over the shield and behind the shield varies for different materials. In most instances this settlement will be 8 0 per cent t o 9 0 per cent complete when the face of the tunnel has travelled a distance equivalent to one to two times the depth of the tunnel past the point of observation.The measurement of surface movements are carried out either: Licensed copy from CIS: URS. aggravation of previous settlem e n t o r t h e bridging of the structures over sections of the settlement trough. 7. O n the centreline of a tunnel the ground movements commence at a distance from the face roughly equivalent t o half the width of the settlement trough. The idealised cases therefore will give a range of settlement but the maximum settlement may be two or three times this value.92 In general the settlement takes place over a relatively short period in most types of ground although in some instances long term settlement may occur. Likewise the plots of readings from different schemes may not be consistent. If the ground moves onto the lining and fills the grouting space the whole of this movement will be reproduced at the surface. precautions will be necessary to restrict slides or falls into the face by using a table or series of tables in the shield.TABLE 11 Development of settlement profile Licensed copy from CIS: URS. have a considerable bearing on the ultimate settlement. With granular materials below the water table ground drainage will be required during the construction of the tunnel. URS Infrastructure. If the tunnel is machine excavated with the shove force from the shield transferred to the lining. the method of construction and the discontinuities in the rock. it is still difficult to predict accurately the settlement which will occur above a tunnel in clay. settlements of the order of 6 to 15 mm have been recorded. within say two diameters. the arching effect above the tunnel will reduce the surface settlement t o a minimum. Type of Ground * Percentage of Total Settlement Completed At Face of Shield At Passage of Tail of Shield % % Sand above water table 30-50 60-80 Stiff clays 30-60 50-75 Sand below water table 0-25 50-75 Silts and soft clays 0-25 30-SO* In the case of tunnels constructed in compressed air these percentages are of the initial settlement. Unlike soft clays and silts little additional movement will normally occur when the air is turned off93.3 the ground movement around the tunnel has been discussed together with the rate of movement axially and radially around the tunnel. In granular soils above the water table the method of construction of the tunnel will have a considerable bearing on the loss of ground. In Section 7. The relation gives an indication of the settlement for tunnels at a depth to diameter ratio greater . In highly fissured rock the several cycles of loading and unloading of the reaction ring at any point as the shield progresses may open up these fissures above the tunnel. If the tunnel is at a considerable depth.4. 7. 04/03/2015. and the lining can be erected and grouted without the ground falling onto the lining. If it is nearer the surface. extending the height of arching above the tunnel 85. For tunnels in weak rock the magnitude and extent of the settlement will be dictated to a large extent b y the depth of the tunnel. Uncontrolled Copy. less settlement will usually occur compared with the arrangement whereby the shove force is provided by a reaction ring which is jacked against the ground. very little settlement will occur. Although the majority of settlement readings have been taken above tunnels constructed in stiff to hard clays.2 Extent of settlement: It is generally found that the volume of the settlement trough a t the surface is approximately equivalent to the volume of the ground lost in the tunnel. 13 and the effect of this movement o n the structure calculated. The method of construction will. In the few cases where readings of surface settlement have been taken above tunnels in granular material below the watertable. If compressed air is used the drainage effect of the tunnel will be reduced and little settlement o n this account will occur. When considering damage to structures above a tunnel the differential movement across the building or section of the building can be assessed from Fig. If the ground is densely packed. larger settlement will occur. however. If the material is loose. Attewell and ~ a r m e ? ' demonstrated an empirical relation for the prediction of settlement in London Clay based on the depth and diameter. Attewell and Boden@ and Attewell and Farmer 79980. again. have discussed the distribution of the loss of ground in the tunnel between Several commentators77. Bartlett and ~ u b b e r and s ~ Attewell ~ and ~ a r m e r divided ~l these figures into face take and peripheral take respectively. When a tunnel is constructed with a pilot. 7.20 m3/m.5 m) Wedge Block lining constructed at a high rate of progress at depth t o diameter ratios of 15 t o 2 0 . The loss at the face will be proportional t o t h e area of the face while that along the tunnel will be proportional to the circumference. and those for the LTE running tunnels of 4 m diameter at depth to diameter ratios of 5 t o 10 when settlement of the order of 6 t o 1 5 m m occurred. including peat. 04/03/2015. probably due to the consolidation of the ground immediately above the tunnel. For London Clay Peck found that the width of the trough was proportional t o the depth.the total inward movements are similar. The few cases of settlement readings for tunnels in silt have recorded movements of 5 0 t o 1 5 0 m m (see Appendix 6).84 have assessed percentages of face and radial take based on monitoring results and on laboratory testing and have shown that up to 2 0 per cent may occur after the lining is erected. Muir Wood 9 showed that when special precautions. URS Infrastructure. additional settlement will occur often one t o two times the original settlement. However.the radial movement over approximately twice that for the face movement .3. were taken for the Heathrow Cargo Tunnel this percentage could be reduced t o 0. T~~ The results of ground movements t o date show that the rate of movement into the face is approximately twice that of the radial movement. there are many factors which affect the ground movements and thus this relation can be indicative only. Special care is also needed in organic soils. when the air is removed. Licensed copy from CIS: URS.4. The radial movement will normally be restricted by the size of the bead on the shield but the rate of movement may accelerate after the tail of t h e shield has passed if the bead is too small. settlements of this order may be expected during the construction of the pilot and. For tunnels in soft clays or silts considerably larger settlements will occur on account of the low strengths of the material. for the main tunnel.0 per cent t o 2. 13 and the maximum settlement. During the construction of the LTE Victoria Line and Fleet Line. when negligible movement occurred (1 t o 2 mm).3 that for tunnels at similar depths and diameters the total movement into the tunnel is not directly proportional t o the rate of progress of the shield. There is still insufficient information to develop formulae for . Typical examples of settlement in stiff clay include those for the small diameter (2. especially in strata other than clay. The use of compressed air will reduce this movement but. Uncontrolled Copy. before more accurate predictions can be made. settlement readings were taken above a number of tunnels at depths varying from 2 0 m t o 35 m and at different rates of progress. at 2 per cent rising t o 6 per cent for tunnels in silt.91 that occurring a t the face. along the shield. b u t that as the movements develop over different times and distances .than three b u t . assuming a constant rate of intrusion into the tunnel. More case histories based on the assumption of high standards of workmanship are required however. and Bartlett and ~ u b b e r s ~ ~ showed that for a number of tunnels in London Clay the cross sectional area of the settlement trough at the surface represented 1. No monitoring has been carried out in these conditions. In the cases of twin tunnels or pilot and enlargement tunnels similar results have been recorded for each drive.17 m3/m and 0. it has been shown in Section 7.3 Discussion on ground movements and settlement: determined the volume of the settlement trough based o n the graph o f the extent of the trough given in Fig. These methods assume a constant rate of intrusion for the average rate of progress of the shield.0 per cent of the area of the face of the tunnel.2 per cent while for tunnels in sand the percentage will be higher. where drainage or use of compressed air may cause dramatic shrinkage of the ground. as discussed in Section 7. and after the erection of the lining. The volume of the settlement troughs per unit length of tunnel have consistently fallen into the range of 0. as discussed above. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. the total ground movement at the periphery of a tunnel but it is likely that the plot of the rate of progress against the inward movement into the tunnel will be of the parabolic form shown in Fig. 13(c). The data in Table 8 suggest that the average rate of intrusion over the shield may considerably underestimate the instantaneous rates of intrusion. 7.4.4 Settlement above multiple tunnels: The pattern of settlement caused by the loss of ground during the construction of two adjacent tunnels in clay has been measured on a number of occasions in the United Kingdom but seldom above tunnels in other strata. In general, the influence of the second tunnel will cause larger settlements than those associated with the first tunnel on account of the disturbance caused by the construction of the f i s t tunnel. During the construction of large underground stations where several tunnels and pilot tunnels may be constructed at close centres, the settlement will generally be proportional to the number of tunnel drives carried out within the vicinity of the point of observation. The influence of the second and subsequent tunnels will normally cause assymmetrical settlement with the greatest value nearest the first tunnel. Fig. 14 gives a typical i ~ l that where two tunnels have a common wall, the settlesettlement curve above two tunnels. ~ e r z a ~ hshowed ment caused by the second tunnel may be less than the first. For tunnels in granular materials the state of compaction of the ground and the watertable level may have considerable bearing on the loss of ground. No readings have been taken above such tunnels in the United Kingdom However, if the first tunnel acts as a drain the settlements in the second tunnel will be lower, but if the ground is loosened above the second tunnel larger settlements can be expected 7 4 . 7.4.5 Settlement above tunnels constructed using pipe jacking methods: Very little information is available concerning settlement above tunnels constructed using pipe jacking methods. In a small number of cases large settlements and heaves have occurred at isolated points probably due t o tunnelling difficulties and losses at the face, or to drag along the tunnel associated with the thrust of the pipe. In general, with pipe jacking the overcut at the shield is less than that associated with the grouting space for a grouted tunnel lining. This space is required solely for steerage of the shield and for lubrication along the periphery of the tunnel, except where intermediate jacking stations are provided. On this account, the settlement a t the surface should normally be less than for a tunnel. In one or two instances a drag effect has been measured which for jackings of 100 m or more may cause more settlement than the initial construction 94. This is illustrated in Fig. 15. New methods of reducing the friction along the periphery, such as the use of anti-drag membrane around the pipe, should reduce this tendency. 7.5 Stresses and hoop loads in linings collected together the available data on the monitoring of stresses in tunnel linings which showed that the majority of the data were for tunnels in clay, mainly London Clay, with relatively little data for tunnels in other soft ground materials. Details of monitoring of tunnels in the United Kingdom are given in Appendix 6. For tunnels in London Clay the first monitoring was carried out for the LTE extension of the Central Line to Ilford in 1942 95. During the 1950's and early 1960's the instrumentation of linings was carried out on a large number of tunnels, mainly with cast iron linings. Most of the instrumentation in the 1960's and early 19703, however, has been in tunnelslined with expanded linings of concrete, cast iron or steel (see Appendix 6). For tunnels in other strata the linings have generally been cast iron with a few examples of other linings, including expanded and grouted concrete linings. In London Clay the monitoring of stresses in tunnel linings during the construction of new tunnels has shown that the average stresses generally increase during the first few months to between 5 0 per cent and 7 0 per cent of the equivalent overburden stress and that,after several years, only a few cases have exceeded 75 per cent. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Higher stress concentrations 95996,97, several times these values have been recorded in the early measurements but these may be partly associated with moment stress. The instrumentation of existing tunnels 50 to 75 yearsold which have been required to be dismantled during the construction of new works has shown combined hoop and bending stresses* before dismantling in the lining equivalent to, or above, the overburden pressure. Where tunnels have been constructed adjacent to existing tunnels the combined stresses in the existing tunnel have increased by between 1 0 per cent and 2 0 per cent as the new tunnel has passed 20 . The instrumentation of cast iron linings has, in a number of cases, shown considerable differences between the stresses in the leading and trailing flanges. skempton9' showed that at Ilford, after three days, uneven stresses developed in one segment with the stress in one flange four times that in the other flange. This particular case illustrates how uneven stresses can be developed where twisting of the joint or 'birdsmouthing' occurs during the erection of the lining. Similar results were obtained at the Ely-Ouse tunnel98 where load cells, in pairs, were fitted at three locations in a number of rings. The loads in the two load cells at a joint often differed by a factor of two or three showing that the rings had been erected out of plane. When expanded linings are used in a tunnel in clay the theoretical initial load placed in the lining may be about 2 5 per cent t o 5 0 per cent of the equivalent overburden load. However, stress readings around expanded rings have shown that the mean load in the lining immediately after jacking may be considerably less than onehalf of this theoretical load o n account of the friction at the interface between the lining and the ground99. The method of expanding, at one or two positions, may have a considerable effect on the load. For tunnels in strata other than London Clay relatively little information is available. In sands below the water table the two sets of readings available have shown that combined stresses between 8 0 per cent and 100 The bending per cent of the equivalent overburden stress may develop within the first few months moments measured in the lining were again large compared with the hoop stress but the total stresses were only a small proportion of the allowable stress in the cast iron. 769100. For tunnels in rock, reading? have been taken of the stresses in the arch ribs prior to the casting of a cast 02. The results have generally shown relatively low stresses, lower than those based on Terzaglu's in-situ lining method7'. This is probably explained by the relaxation of the ground on account of the compressibility of the packings between the ground and the arches. Strains measured in a precast concrete segmental bolted lining in limestone are difficult t o interpret on account of the extent of overbreak and the difficulty of relating strain to stress 34. 7.6 Recent instrumentation and monitoring of tunnels As discussed in the previous sections instrumentation and monitoring of tunnel linings and ground movements were carried out in a number of tunnels, mainly in London Clay, during the 1950's and 1960's. During the last few years the number of projects carried out or in progress has considerably increased partly on account of the increase in tunnelling in the period but mainly following the expansion of the research effort on tunnels. There are many gaps in the present knowledge of the behaviour of the ground and of the lining as a tunnel is constructed, as discussed in the previous sections, and thus the provision of the major part of the money for such work by a central organisation with a co-ordinated policy should lead to a constructive overall programme of work. * Subsequent references t o 'combined hoop and bending stresses' have been abbreviated to 'combined stresses'. 52 The monitoring of surface settlements, which is already carried out on many medium and large diameter tunnels, to detect possible damage to structures above the tunnel, should be carried out on more small diameter tunnels as part of the normal site checking. A summary of the instrumentation of tunnel linings and ground movements, with the exception of surface settlement readings, which have been carried out during the last two or three years or which are at present in progress is given in Table 12. Further details of these projects, are given in Appendix 6. TABLE 12 Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Recent instrumentation and monitoring of tunnel linings and ground movements Organisation Location Strata Date Binnie and Partners Kings Lynn Silt 1974 Horizontal ground movements and surface settlement readings around a 1.2 m external diameter tunnel at shallow depth 82. Building Research Establishment Kielder Northumberland River Authority Mudstone Limestone Sandstone 1974-75 Instrumentation t o date in mudstone for comparison of different linings with drill and blast or roadheader machine excavation. The linings, 3.35 m external diameter, included steel arches and laggings, fully bonded resin anchor bolts, shotcrete and a thin steel liner. The final section was left unsupported. The ground movements around the tunnel were measured with extensometers at two sections for each of the linings. Ground movements ahead of the tunnel were measured in two deep boreholes. The investigation will continue during the main contract for the tunnel 7 0. Channel Tunnel Consultants and Newcastle University Dover, Channel Tunnel Lower Chalk 1974-75 Measurements of ground movements around 5.3 m diameter tunnel at considerable depth, lining loads and stresses in tunnel lining including specially designed deformable lining 103,104 Durham University London London Clay 1972-73 Vertical and horizontal surface and ground movements at three cross sections for 4.1 m external diameter tunnel at depth 79,80 Tyneside Hebburn Laminated Clay 1973-74 Vertical and horizontal surface and ground movements at a number of positions along and transverse to the centreline of 2.0 m external diameter tunnel at medium depth. Measurements of axial movements and movements into the face 8 4. Tyneside Tyne Syphon Coal Measures 1974 Measurements of ground loadings and of lining stress in 3.4 m diameter tunnel 105. Instrumentation and Monitoring TABLE 12 (Contd) -- Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Organisation Location Strata Tyneside Willington Gut Silty Clay Measurements of vertical and horizontal surface and ground movements and of porewater pressures at one section for 3 m external diameter tunnel at medium depth, constructed with the use of compressed air 8 3 . C K Haswell and Partners Severn-Wye Limestone Measurement of lining stresses in 3.4 m external diameter tunnel 34 . Newcastle University Mersey Kingsway Tunnels Bunter Sandstone Measurements taken, in twin 11 rn external diameter tunnels, of interaction of rock stress pattern due to two tunnels at 27.5 m centres, stresses due to construction of second tunnel, deformations of the lining, stress in the lining and outside water pressure readings 106. Cleveland Potash Boulby Shaft Mersey Railway Liverpool Loop Transport and Road Research Laboratory Date Instrumentation and Monitoring Measurements of inward movements at considerable depth of soft material 107, Boulder Clay Measurements of settlement and vertical ground movements and tilts above concourse constructed in various stages, stresses in the lining and bolts loads87 . London Fleet Line New Cross Gravel Measurement of vertical and horizontal surface and ground movements and porewater pressures around 4.1 m external diameter tunnel at shallow depth constructed with bentonite machine 8 6. London Fleet Line Regents Park London Clay Measurements of vertical and horizontal surface and ground movements and porewater pressures around two 4.1 rn external diameter tunnels at medium depth, lining loads, stresses and deformations 8 1. Chinnor Lower Chalk Measurements of vertical and horizontal surface and ground movements around 5.0 m external diameter tunnel a t shallow depth in vertical boreholes and from adjacent shaft in horizontal boreholes. Rockbolting and shotcreting trials 85,89,108,10$ Warrington Sand Measurements of vertical and horizontal surface and ground movements and porewater pressures around 2.8 m external diameter tunnel, at shallow depth, constructed with bentonite machine, (in progress). 7.7 Research Research in the laboratory into tunnel linings and ground movements associated with tunnelling has been carried out by BRE, TRRL and the Cement and Concrete Association (C & CA) and at Universities. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Laboratory research into tunnel linings has usually taken the form of load testing of a single segment or group of segments t o compare the theoretical results with the actual measurements. The earlier tests were carried out on grey cast iron segments but since the late 1960's much of the work has been carried out on spheroidal graphite iron. Some cases are discussed in this section. In the mid 1960's research was carried out at the Civil Engineering Department at the University of Glasgow into the stresses associated with the tightening of bolts within a group of segments. This work confirmed that substantial stresses can be built up during the tightening of the bolts and theoretical methods were established t o enable these stresses to be calculated. The research was based on the correct building of the segments with complete bearing between the faces of the segments. In practice due to errors in the alignment of the tunnel and to foreign matter being lodged in the joint, bird's-mouths occur, thus affecting the stress distribution. The joints between the segments seldom transmit moments across from one segment to the next unless friction grip bolts are used. During the construction of the LTE Victoria Line extension to Brixton a number of spheroidal graphite rings were incorporated into the pilot tunnel for one of the crossovers as described in Section 4.1 and the stresses and deformations monitored by the BRE. Parallel experiments were carried out in the laboratory t o compare the predicted stresses in the lining, by plane circular bending methods, with those measured using strain measuring instruments. Previous experiments had showed that with the conventional grey iron segments beam theory applied where the segments were loaded at quarter points. For the thinner and wider spheroidal graphite segments experiments showed that the theory did not hold unless a uniform loading was applied. These experiments were therefore carried out with the load applied using a flat rubber bag. The results showed that those types of segments behaved essentially as two independent units of skin and flanges Research work has been carried out by the Department of Mining Engineering of the University of Newcastle upon Tyne on the stresslstrain behaviour of a spheroidal graphite cast iron segment. Uniformly distributed loading was applied through a loading plate comprising a layer of sand on the back of the segment. The work concluded that the circular bending theory was not directly applicable to the segment analysis and that several variable and complex factors make a critical analysis difficult - these are the variation in section modulus and of external loading. 20977. These and other experiments on the behaviour of cast iron linings under load are necessary t o help to establish the complex relations. However, perhaps more important is research into the stresses and deformation associated with a complete ring of segments. Discussions have been held in the last few years with a view to carrying out an experimental programme using a 4 m diameter spheroidal graphite lining but the project is unlikely to be carried out on account of the prohibitive cost of the testing (see Section 13.3). At the Engineering Geology Laboratories at the University of Durham, laboratory experiments have been carried out using a clay extrusion technique on 100 mm diameter samples 88. These experiments have included strain and stress extrusion tests and a dyed-layer extrusion test (see Appendix 6). From the results, rates of intrusion of the material into an excavation are calculated, from which the theoretical settlement associated with tunnelling through the particular type of strata is predicted. The approach is in its early stage of development and data are required from many more schemes before a reliable system can be evolved and the scale effects assessed. The small number of test samples for any particular scheme also imposes limitations on the predictions 88. ' Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. A t the Engineering Department at the University of Cambridge 1°yl 12,research is in progress in which methods o f analysis are combined with model testing including the use of a centrifuge, to investigate the deformation of ground around a tunnel. The initial work considered the question of the stability of a shallow unlined circular tunnel supported by a uniform internal pressure. By using the theory of plasticity a relatively simple solution was obtained for the particular case in which a uniform surcharge pressure was applied at the soil surface with t h e self-weight o f t h e soil neglected. Later work has investigated the stability of tunnels in real soils such as dense sand whose self-weight may itself cause instability. These tests have been designed to enable the behaviour of t h e tunnel and the deformation of the soil t o be studied throughout the test. Theoretical solutions have been drawn u p in parailel with the work. The results demonstrate the inherent stability of a tunnel in dense sand at any d e p t h provided the integrity of the tunnel is maintained. The research has shown that the collapse mechanism can be simply modelled, leading t o varied theoretical solutions. 7.8 9' Development When new linings are designed and developed experimental work in the laboratory or on a site is often carried o u t t o check o n t h e suitability of the lining. This work may consist of simple load testing experiments on segments o r more sophisticated loadings o n a complete lining in the laboratory or below ground level. The development o f a lining also includes full scale erection tests in a tunnel, preferably behind a shield where the lining may be studied during handling, erecting and shoving. Where new components are used in a lining these should be adequately tested for a trial length of tunnel to avoid teething difficulties when the lining is used for its first few schemes. Testing of linings in their early stages of development has been carried out since the turn of the century. When the McAlpine Lining system (see Section 5.6) was developed, large scale testing, using bolts uniformly loaded and point loaded rings, was carried out in 191 1 on different materials to compare their strengths. In 19313 4 more extensive tests were carried o u t on the lining where the lining was compared with the standard brick construction. In 1933-34 rings of lining of 2.2 m diameter were tested to destruction in the laboratory at Imperial College in London during five tests with different horizontal and vertical loadings on various forms of lining 49. Extensive testing was also carried out in the mid to late 1930's when bolted concrete linings were developed for t h e LTE extension o f the Central Line t o Ilford. These included loading tests on rings erected several feet below ground level with the use of many hundred tonnes of kentledge. The tests on the full-scale prototype behind a shield were n o t successful and led t o a redesign of the cross section of the (see Section 5.4). Similar kentledge tests have been carried out when developing other new linings: a number of rings of the new lining are erected alongside rings of conventional linings and the deformation monitored as the kentledge is increased. The development of a permanent test rig, as discussed in Section 13.3, would be of considerably more use for such testing. Alternative laboratory testing of new linings has included the point load testing o f segments t o compare them with existing linings. When special solid linings are developed for particular tunnels t h e design of the longitudinal joint between segmefits requires critical analysis. To help in the design of articulated joints, which are discussed in Section 5.3 and which may be either flat, convex/convex or concave/convex, laboratory testing has o f t e n been carried o u t . Test samples of the ends of the two segments, of sufficient length to avoid any end effects, are cast and tested in specially designed rigs to investigate the behaviour of the joint and of the stresses imposed in the segments. Such tests have been of particular importance in comparing different joint profiles and in establishing the quantity of reinforcement required in the segment to prevent bursting. Details of some of the experiments are discussed in Appendix 6. 8. DESIGN 8.1 Design methods Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. The instrumentation and monitoring of tunnel linings and of ground movements has been discussed in Chapter 7 where it has been shown that for soft ground tunnelling: a) The hoop loads in the lining may build up over a period of months or years to a value equivalent to the full overburden pressure and has only exceeded it in one or two instances. Generally, however, the hoop loads have been equivalent to approximately 75 per cent of the overburden (see Section 7.5). b) Additional distortion may be imposed on the lining by the construction of adjacent tunnels on account of the reduction in the lateral pressure and of local concentrations of load. c) The linings deform after erection as the loads in the lining build up and as the lateral loading is mobilised by compression and shear between the ground and the lining. d) Vertical and horizontal ground movements are associated with the construction of a tunnel. The extent of these movements depends upon many factors and considerably more instrumentation and monitoring are required before an adequate understanding of the ground behaviour can be established. One factor which has a considerable bearing on the movement is the period which elapses between the excavation of the tunnel and the time the lining takes to begin to carry its share of the load. There has been comparatively little instrumentation and monitoring of stresses in tunnel linings in weak t o moderately strong rock in the United Kingdom and much of what exists is of dubious value. The fundamental design concepts of elasto-plastic behaviour of the ground and the concept of relative compressibility of the lining are widely accepted. However, the data used for such analyses remain inadequate and insufficiently related t o the "mass" properties of the ground. In engineering terms the competence of a rock is a measure of its capacity to resist deformation under a given loading. Since the loading is usually directly related to the weight of overburden the competence factor (Fc) is defined as1 where P is the unconfined compressive strength of the ground and a, the initial vertical stress at the tunnel axis level in the ground. This is twice the reciprocal of the more commonly used stability ratio. The stability ratio (N) was developed by Broms and ~ennermarkll 4 from earlier related work on bearing capacities of deep foundations and is defined as Where PZ is the total vertical pressure at depth Z Pa is the air pressure above atmosphere Cuis the undrained shear strength of the clay Thus a competence factor o f 0.5 is equivalent to a stability ratio without the use of compressed air of 4, similarly competence factors of 2 and 1 0 are equivalent to stability ratios of 1 and 0.2 respectively. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Where Fc is less than 2, immediate support t o the ground is required. If Fc lies between 2 and 1 0 the stability o f the ground in the unsupported state will depend upon the initial state of stress and on the time dependent stress-strain characteristics. The excavation for the tunnel will cause negative porewater pressure in the ground, the rate o f dissipation of which will control the behaviour of the ground. Where local overstressing of the ground occurs, support will be required. If Fc is greater than 1 0 the ground will be competent and the main problems will be associated with the discontinuities in the rock or soil. showed that from a n analysis of a number o f case histories in plastic clays, tunnelling could be carried o u t without unusual difficulty when the stability ratio was reduced t o 5 or 6 or below with the use of compressed air. The tunnel lining and the surrounding ground require t o be treated as a composite structure for the analysis of t h e state of stress and deformation. The over-riding parameters for this analysis are the relative stiffnesses of ~ ' formulae for (a) the stiffness ratio (that is, the ratio of the stiffthe lining and t h e ground. ~ o r ~ a nexpressed ness o f the tunnel lining t o that o f t h e surrounding ground) for the simplest elliptical mode of deformation of a circular tunnel and (b) the bending moment in the lining. This type of approach contrasts to the design of overstiff linings o f very high stiffness ratio. 8.1.1 Soft ground tunnels: The soft ground tunnels constructed in the United Kingdom during the last century and the early part of this century were lined mainly in brick, masonry or cast iron. The thickness of the linings had been established mainly b y trial and error and in particular the sections for the cast iron linings were generally very conservative for the permanent conditions, on account of the large temporary stresses during erection and the casting requirements for the segments. Based on these trial and error methods, rule-of-thumb dimensioning of t h e cross section o f the cast iron linings was available for cohesive and waterbearing soils 115. The following requirements should be taken into account in the design of a tunnel lining for soft ground. a) The stresses associated with the short term and the long term loadings from the ground, including those from any probable future tunnels or buildings nearby. The deformations caused by these loadings should be k e p t within the limits appropriate to the particular lining. b) The a m o u n t o f leakage which will be tolerated in the completed tunnel, taking into account the deformation of the lining in (a). As discussed in Section 13.4 the method of waterproofing the joints should be taken into account during the design stage. c) The impact stresses during the handling, transporting and erection of the segments. d) For shield driven tunnels the loadings associated with the shoving of the shield. e) The cost of casting and erecting the lining. The design should, where possible, take into account the probable tunnelling method and method of erection of the lining. The ideal lining should form part o f a fully integrated system. Grey iron is a material of low tensile strength, thus the sections have been designed to take the temporary conditions o f handling, erection and bolting and the shoving forces from the shield. For the permanent conditions these linings often had a factor o f safety of 4 to 1 0 and thus additional stresses imposed on the lining by the construction of adjacent tunnels did not generally cause distress to the lining, provided measures were taken to limit any excessive bending arising from distortion of the cross section. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. In the early part of this century these linings were often designed using the method proposed by Hewitt and ~ohannesson' which was developed for shield driven tunnels. This method takes into account the lateral support provided by the ground and the lining-soil interaction but it was assumed that the line of action coincided with the centreline of the section. The tunnel was regarded as a continuous rigid structure both in the temporary and permanent conditions. For the temporary conditions during the erection of the lining and for an unsupported, ungrouted ring it was assumed that the dead load of the ring was supported on two knife edges near the invert of the tunnel. For the permanent conditions it was assumed that the lateral pressure lay between the values for the active and the passive pressures, the actual value being chosen according to the expected ground conditions. This design method, however, used the right basic approach for tunnels with low cover and a small competence factor. Many other design methods have been developed in the last thirty years for cast iron lined tunnels, several of which have been described by Szechy 16. These methods generally make arbitrary assumptions for the loading on the lining and give a large variation in the values for the stresses and moments, and thus for the stiffness of the linings, when compared for similar tunnel conditions. One such method is that developed by ~ u l l l' 7 (see Appendix 7). The results of'the instrumentation of the lining for the SizewellTunnel (see Appendix 6) were compared with several theoretical methods. Bull's method was found to give the closest correlation to the measured stresses. The majority of these methods, however, have been little used in the United Kingdom. Cast iron segments are bolted together in rings to form a cylinder. In the longitudinal direction the flanges are machined and theoretically there should be only small bending moments associated with the tightening of the bolts (see Appendix 6). In practice 'birdsmouthing' occurs on account of the incorrect building of the ring and considerable bending moments may be built into the flanges; these are referred to as the building stresses. However, on account of the large factors of safety the longitudinal flanges seldom crack. During erection, bolting, grouting and caulking, which is often carried out at a later date, stresses may be built into the lining which may affect considerably the stress distribution around the ring. For this reason it is often difficult to correlate the measured stresses in a lining with those calculated by theoretical methods. When precast bolted concrete linings were introduced in the late 1930's the linings were designed generally to the same profile as the cast iron linings, with an increase in the thickness of the flanges and the skin to allow for the reinforcement. The segments and rings were test loaded, as described in Chapter 7 and compared with the cast iron segments. The lining was also erected in a tunnel behind a shield, as discussed in Section 5.4, and following damage caused by the shield rams the lining was strengthened. The present standard bolted linings have evolved from the original linings, as discussed in Section 5.4 and are generally designed for tunnels up to 30 m in depth. The design of these linings is often carried out using the formulae developed by ~ o a r k l' 8 in "Formulae for Stress and Strain" for rings and pipes. The temporary stresses in linings developed during handling, erection and shoving of the shield are, however, more critical and the skin in the standard designs are more likely to crack, than cast iron, when excessive forces are applied from the shield rams*. The reinforcement in the segments will mainly be required for these temporary conditions of handling, erection and shoving. When articulated and expanded linings were introduced in the 1950's more attention was given to the design of the linings. The segments for these linings are solid and are not bolted together. The stresses in the segments at and near to the joints become critical. - * - - In practice spalling and cracking may also occur with solid smoothbore linings but these are often caused by the lining being out of plane or, in a few cases, when the position of the rams coincides with the joints between the segments in the ring. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. ~ o r ~ a proposed n ~ ' a method of analysis which was originally developed for tunnels in London Clay but which has subsequently been used for many tunnels in soft ground or weak rock (see Appendix 7). This method considers the state of stress around a circular hole at depth and in particular the loading on the lining from the ground. When a circular tunnel is subjected to ground loadings it deforms to an ellipse causing bending moments in the lining which can be related by conventional beam theory to the deformation. The stress in the ground set up by the deformations can be represented by a stress function from which the radial and circumferential stresses can be determined for certain boundary conditions. The changes in horizontal and vertical loadings on the segments, and thus the moments, can then be assessed for this passive loading and the moments for the active ground loadings superimposed. The extreme fibre stresses can then be determined by the addition of the hoop loadings. These stresses are related t o the elastic modulus and Poisson's ratio of the ground. The introduction of articulated and thinner linings also required the stability of the lining, which evolved from the loading formula, to be determined. Several commentators have observed that Morgan's analysis3' contained some errors apart from the intentional simplifying assumptions. The shear stresses between the extrados of the lining and the ground were neglected which in turn simplified the solution. The main 'error' concerned the assumption that the plane strain entailed plane stress which lead t o a higher value by a factor of 2 to 4 for the coefficient of ground reaction. Muir wood1 l 9 modified the Morgan method and corrected the basic errors while at the same time updating the method from the practical experience of the intervening years (see Appendix 7). The stiffness ratio is incorporated and he shows that if this is taken into account there is a reduction in the bending moment in the lining. The effect of the shear forces between the ground and the lining and a compressibility factor are also introduced. The,compressibility factor is the compressibility of the tunnel in relation to that of the surrounding ground and thus if a high factor is provided the loading in the lining is reduced. The work of Muir wood1 19, however, although updating ~ o r ~ a n ' shas ~ ' been further discussed by curtis12' and Muir w o o d l 2 l . Other methods have been introduced overseas in the last decade which have been mainly used for tunnels ~~ which is based on the theory o f cylindrical in granular material. These include Schulze and ~ u d d e c k ' s lanalysis shells and assumes that the ground does not offer support to the lining in the crown of the tunnel (see Appendix. 7). An active loading for bending equivalent to the overburden pressure is used which gives a stiffer lining than the British methods. The value for this active pressure is likely to be highly conservative and it is hoped that the present research at Cambridge (see Section 7.7) will provide more realistic loadings and methods of analysis. In most of these design methods the formulae for the stresses and bending moments in the lining depend upon geotechnical parameters which are often difficult to assess accurately for the particular and varying ground conditions near a tunnel. In some cases, however, the methods entail simple analyses of the design of the lining which give at least an indication of the order of magnitude of the likely stresses and moments. For articulated linings, the problems of unknown secondary stresses may often be kept to insignificant levels. ~ e c kintroduced ~ ~ $a semiempirical ~ ~ ~ approach to design where the lining is first designed for the ring loading and then the bending moments for the normal deformation of the lining and for the local irregularities of loading and stresses (see Appendix 7). Peck shows that there is a theoretical maximum ring load which the lining would need to sustain if the tunnel were constructed instantaneously but that, on account of axial and radial deformation of the ground as the tunnel face approaches, during the construction and until the load builds up in the lining, the theoretical maximum load is smaller than this value. He suggests, however, that the ring load should be based o n the overburden pressure as there are insufficient data realistically to justify reducing this value. For heavily over consolidated clays he suggests that the assumed ring load should be increased for values of KO,the coefficient of earth pressure at rest, greater than 1. As discussed above this is not generally confirmed by the results of instrumentation. A high KO must be associated with a certain minimum permanent shear strength of the ground. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. ~ e c kassesses ~ ~ the , magnitude ~ ~ ~ of the deformation for a perfectly flexible lining and checks for stability against buckling. The lining can then be designed either as a flexible lining which will then take this deformation or as a rigid or semi-rigid lining which should not be overstressed with these deformations. The deformation of the lining should take into account any relaxation of lateral pressure associated with the possible construction of adjacent tunnels. In addition the lining should be designed for any additional loads due to shield forces, irregularities of loading, or distortion in the longitudinal direction. These may be covered by an increase in the factor of safety. ~ u r t i s discusses '~~ the visco-elastic method of analysis which enables the time-dependent effects, such as consolidation and creep to be taken into account. Using the Kelvin Model he develops formulae for a number of viscoelastic situations. The analysis initially studies the case of a lining installed instantaneously, which gives the long term solution, and this is modified for the delay in inserting the lining. A further analysis is carried out to study the stress changes in the ground and added to the results of the first analysis. The formulae are derived for a thick lining subjected to a uniform radial load and a distortion load and for the case of the construction of two adjacent tunnels. The basic principles of the British approach to the design of tunnel linings, which are shared by some American and other overseas countries, but not generally by the Germans are for a light, flexible, compressible lining. The ' ratio of the stiffness and compressibility of the tunnel lining to that of the ground, whilst having a considerable bearing on the stresses to be carried by the lining, have a reduced effect on the ground and lining deformations. When tunnels are constructed alongside existing tunnels there will be a reduction in the lateral soil support pressure on the existing tunnel and a corresponding asymmetrical increase in the deformation of the lining. The distortion associated with the construction of adjacent tunnels is discussed in Section 7.2. Other data on foreign tunnels are given by Except where tunnels are constructed closer than half a diameter the effect is relatively small, increasing the stresses by 10 per cent to 20 per cent, except for ground of a very low competence factor. The effect of the ram forces from the shield, handling, and erecting forces should be assessed for the lining. The ram forces may be calculated from the jacking forces acting longitudinally on a segment and the stresses calculated on the cross section. If several rings are ungrouted, longitudinal buckling or lateral displacement may occur. The handling stresses are normally associated with segments being dropped either singly from 7. height or a number of segments falling onto a segment. This requires conventional structural analysis as discussed in Appendix 7. The effect of bolting stresses is discussed in Appendix 6 . 8.1.2 Rock tunnels: Numerical methods, particularly finite element techniques, are now being widely used for the design of tunnel linings and to analyse the behaviour of the rock. They are of particular value where large underground chambers and passages are to be constructed, where finite element methods have great potential in analysing stress and strain distributions. Many different programs are available from which to choose the most suitable for the individual requirement of the geometry of the tunnel and the material properties of the ground. The analyses are normally two-dimensional; although three-dimensional methods are available the computer storage capacity required for the complex problems often makes them uneconomic except for academic study. In general, errors in the prediction compared with the outcome are not due to the use of two-dimensional methods for three-dimensional problems but are due rather to the incorrect rock mass idealisation. If a fraction of the expenditure on finite element systems had been spent on trying to understand the mass properties of jointed rock t h e present state of the art would be far more advanced. Finite element techniques may be used not only for stress analysis b u t also for water flows and seepage problems, when great care is needed in taking account of inhomogeneit y. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. The principles of finite element analysis are easily understood but the programs are complex and to avoid misuse require considerable knowledge and practice in their use. For non-linear stresslstrain analysis t h e procedure of loading is of considerable importance since there is no unique solution and superposition is no longer possible. The main scope at present for finite element techniques lies in parametric studies, i.e. the examination of the variation in the different variables and in considering the failure modes in relation t o the joint pattern. The shortcoming of the technique lies in the fact that n o tunnel goes through strictly isotropic ground and that the soil and rock parameters are t o some degree variable. While soil may be treated as a continuum without too much error, for rock the discontinuities are more important than the rock sample properties, consequently certain finite element models attempt t o model the joint behaviour. In designing experiments in real ground, too little heed is often given t o such factors so that the results appear scattered and inconsistent. To enable more precise modelling many m o r e case histories are required for analysis coupled with research. In this connection the present model analysis a t Cambridge University (see Section 7.7) should help t o give a better understanding of the problem. For simple two-dimensional problems, elastic study may be undertaken cheaply using photoelastic models. Jelly and frozenstress photoelastic models also often serve to provide adequate information on 3-D problems. The most versatile of the several methods for finite element analysis is the use of standard elements which correspond t o the rock mass and special elements t o model the discontinuities and simulate joint movements. Likewise, t h e method o f excavation (drill and blast or machine excavation) may have a considerable bearing on t h e extent t o which the discontinuities may open, which may well affect design assumptions 125,126,127 Design methods such as those outlined above are of great help to get the 'feel' of the problem b u t with the present knowledge they require empirical calculations to confirm their predictions, and they will always require to be complemented by engineering judgement. If simple programs can be built up following the initial design they may be of considerable use during the construction if input data are modified as the ground conditions and tunnel behaviour become clear, thus enabling new predictions to be made for lining thickness, ground support, rock bolting, and similar aspects. The extent of the need for a primary lining in a rock tunnel is governed by the response of the rock mass to the stress redistribution following excavation. Many factors affect this redistribution including the initial state of stress, the shape, size and depth of the excavation and the method of excavation. Calculations, model testing and finite element analysis methods, are available to analyse the stress fields but generally the information on the geological data, the rock mass behaviour and the in-situ state of stress are insufficient. The in-situ rock stress may be inferred from strain measurements at selected points but no universal calculation methods are available. The vertical component of the stress may be as high or higher than the average overburden pressure, while the ratio between principal stresses depends on the geological history, but in soils cannot exceed the coefficient of passive earth pressure (Kp)*. For a tunnel at depth an initial approach based on the theory of elasticity may be appropriate. * K p = an' (45 + 01/2) + density of the material. y Tan (45 + @'/2) where s@ i' the angle of friction, c' the cohesion and 7 the immersed In an elastic continuum the redistribution of stress following the advance of a tunnel will be complete when the face is several diameters beyond the point of observation. In nonelastic media, however, the deformation may continue as the rock around the opening adjusts to the new loadings causing tension cracks and the opening of joints. As discussed above in general the greater the deformation the lower the final load which the lining will be Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. required to withstand (see Fig. 16). Thus if a stiff costly lining is erected immediately, the load in the lining will be hlgher than if a more economical deformable or yielding support is used. Similarly, if the excavation takes place in stages, the effect on the stress pattern of each stage of the excavation should be taken into account. While the deformation of the rock is continuing visual inspection and measurements are essential. If the rate of deformation is decreasing the support is usually adequate. An alternative method, and a safer rule, may be based on a plot of deformation against time. If the slope is increasing, additional support will be necessary. The support needed for an excavation will be influenced by the discontinuity characteristics of the rock and thus a series of zones should be designated, t o cover the extremes of rock jointing conditions likely t o be encountered, entailing studies of degrees of fracturing and analysis of preferred joint directions, using graphical methods. Zoning techniques are valuable, using simple tests whereby designs are prepared for each zone type of ground encountered. The most widely used forms of ground support are steel ribs and lagging, rock bolts and sprayed concrete. Where a primary lining is required, this is normally cast in-situ concrete. The rock loads associated with ribs and lagging and the primary lining have normally been designed using Terzaghl's method7l, which was the first rational approach t o evaluating the rock loads (see Appendix 7). In the absence of quantitative information on joints, this method is the best basis available, but should be modified in relation to experience and engineering judgement based on the particular tunnel conditions or instrumentation results. The method was designed for tunnels excavated by drill and blast methods and assumes that a bridging ' a table which gives effect occurs above the tunnel thus forming a rectangular shaped loading. ~ e r z a g h i ~gives typical rock loadings for different types of ground conditions based on the width and the height of the tunnel (see Appendix 7). Terzaghi was principally concerned with relatively rigid tunnel supports. More recent methods64 take account of the ability of rock bolts, where suitably disposed, to cause the rock to act as an arch, thus relieving the dead load to be accepted by other means of support. When designing for rock bolts a knowledge of the state of stress of the rock, its physical and mechanical properties are again essential. The several forms of rock bolts commonly used have been discussed in Section 6.2. The design for a rock bolt system has developed partly by rule of thumb methods which are based on experience, and others. The important variables are length but far more by the simple type of analysis advocated by and density of the bolts, working load, pre-load and stiffness. Several design methods have been put forward, including those of ~ o o d m a 129 n and Ortlepp 30. an^^^ The bolts must be of sufficient length to prevent the collapse of the beam or arch formed by the rock and the bolts around the soffit of the tunnel. The bolts must be close enough to prevent individual blocks falling out with additional support provided such as steel mesh or steel plating if required. The tension in the bolts once built up by the rock load or by pre-tensioning must not be allowed t o relax unduly on account of movement of the rock, although in certain circumstances bodily movement of the rock bolt may be permitted. Routine checking ofthe bolt tensions should be carried out to ensure that the anchorages are not impaired by blasting damage 131. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Pull o u t tests in the type o f rock likely to be encountered are essential unless other information from other tunnels is available for comparison6'. Finite element analyses have been undertaken but it is unlikely that these have been very seriously used as a basis for design. Coates et adopt the generally accepted view that the rock under tensile o r low compressive stress is that most likely t o fail. He suggested that where the length of the bolt is greater than a quarter o f the span, the spacing should be less than 0.8 of the length of the bolt. If the length is less than a quarter span the spacing should be half the length. The spacing should not at any time exceed three times the joint spacing unless a wire mesh is used to help support individual blocks. Other approaches which are widely used suggest closer spacing, of 113 t o % of the span of the opening with a length to spacing ratio of at least 2%. The extent o f the rock around the crown which is t o be bolted depends upon the nature of the rock and the jointing pattern. Measurements o f the deformation of the rock will give data on the diametral strain and thus the in-situ state of stress. Rock reinforcement may show signs of distress where the diametral strain increases above 0.2 t o 0.3 per cent. For the design of sprayed concrete for tunnels Terzaghl's theory of rock loading cannot be used. The essential object of the sprayed concrete is t o form with the rock, a compressible stressed arch. Design methods based o n shear strength of the sprayed concrete may overestimate the thickness since they do not represent the interaction between rock and concrete shell. Most design methods for sprayed concrete with or without rock bolts have been developed b y trial and error and are normally specific to limited ranges of ground conditions. The methods are often tied t o ground classification systems, such as Rock Quality Designation (RQD). There is a great need for more meaningful methods of classification. Several classification systems have been evolved, the more ~, et allo, ~ieniawski'l , Barton et all2, ~ a u f f e r ' and ~~, recent of which have been proposed by ~ e e r eFranklin ~ e c i l 34. ' Each system provides guide lines for the extent of support required for various rock types based on classification factors. The qualitative assessment of jointing (whether open, nature of filling etc.) is the most difficult factor t o represent adequately in numerical terms. A study of case histories for similar types of ground conditions is a considerable benefit 6 8 . The new Austrian Method of t u n n e l ~ i n ~which ~ ~ ~has , ' been ~ ~ used for many tunnels in Europe is based on the principal t h a t it is desirable t o take advantage of the capacity of the rock being able to support itself. The method generally incorporates t w o stages of support: the first a flexible arch designed to 'stabilise' the structure, of rock anchors and sprayed concrete surface protection. The second support is an inner concrete lining. The first support is based o n a predicted curve of radial stress against deformation which is confirmed by measurements in the tunnel and additional support given where necessary. 8.2 Joints in linings With the introduction of articulated linings the design of the joints has become particularly important; model or full scale testing is normally required during the design stages. For the LTE Victoria Line tests were carried o u t on the design of concave/convex and convex/convex joints (see Appendix 4), which gave the load characteristics for different radii o f curvature of the joint and the angle of movement 231137. These showed that for the concave/convex joint the joint strength decreased by up to 5 0 per cent as the angle between the two segments increases from zero t o 3O, on account of the change in the relative geometry of the contact surface and the boundary of the segment. The testing of such joints gives a good indication of the mode of failure (see Appendix 4). The maximum compressive stress at the area of contact of the joint is many times higher than that in the rest of t h e segment. The joint acts as a plastic hinge. Theoretical methods of analysis of the joint stress are best carried out using finite element techniques based on the design loading and assumed figures for concrete strength. In using these methods reference should first be made t o joint configurations which have been used previously to check on the design basis (see Section 5.3). during the construction of the opening. For a two ring opening the transfer of this load is unlikely to overstress the jamb rings if adequate factors of safety have been used in the design of the standard lining. without distress. Where the extraction is of a small thickness the movement may be considerably less. Uncontrolled Copy. .3). d) For solid concrete segments. the development of this profile as the mining face approaches and passes the tunnel. 8. These include: a) The use of a rectangular frame of special segments.8. In general the effect of mining is to cause extension. 04/03/2015. To reduce needs for temporary support of the tunnel soffit and invert segments.theload may be transferred by a series of brackets as each ring is broken out.32.(see Section 17. settlement over the area will be fairly uniform except for areas where there are hard spots or faults. shear pins between the segments may be used (see Figs. is the most important part of the design of the tunnel. however. b) Steel segments above and below the opening bolted together with friction grip bolts or shear pins t o form beams which transfer the loads to the adjacent rings. 17 and 18).8.8 per cent of the diameter of the ring.3 Openings in preformed linings Licensed copy from CIS: URS. URS Infrastructure. The lining must be designed t o sustain. The lining must be flexible in the longitudinal direction with compressible jointing material designed t o extend and compress as the settlement profile is developed. subsidence and compression. The correct geometry of the joints.6 m wide standard rings the maximum movement which is likely to occur on account of extraction of future coal seams is 0. Several methods of transfer of this loading have been used or proposed which essentially produce a structural beam above and below the opening. If the space between the segments is too small cracking of the flanges or spalling of the concrete will occur.4 Linings in mining areas The design of tunnels in areas where mining is or will be carried out requires a knowledge of the way the settlement profile develops138 caused by mineral extraction. For larger openings prestressing bars have been inserted through sleeves in these segments and stressed to form lintels above and below the opening 35. The thickness of this jointing material must be sufficient to allow for this movement without unsealing the joint. Semi-circular holes are cast in the circumferential joint of the segments and the circular hole formed between two adjacent segments filled with dry packed concrete. The National Coal Board (NCB) have estimated that for the present 0. For the design of openings in preformed tunnel linings for access passages and ventilation openings the load in the rings from which the segments are removed is transferred t o the adjacent jamb rings. Methods available for tunnels in mining areas are discussed in Section 10. whether they are specially designed or conventionally bolted segments with loosened bolts. special jambs will be necessary or alternatively the load should be transferred to at least two rings on each side of the opening. For openings greater than two rings. picture frame or shaped voussoirs around a curved opening. c) Removal of the segments directly above and below the opening and a steel lintel beam and sill inserted to take the loads. Following extraction. The temporary measures available t o reduce the ingress of water during the construction of a tunnel have been discussed briefly in Chapter 6 .some of which will take a little movement. leading the water in channels behind a facing o r canopy has been considered acceptable. For cable tunnels a dry environment is required when the cable jointing is in progress. In road tunnels seepage water is unsightly and should be led behind a watertight secondary lining t o the invert drainage system. In general a cast iron lined tunnel adequately caulked with lead or with a butting neoprene seal. If. The permanent measures commonly used to seal the primary lining are discussed in this chapter. although trials have been used with a large number of different types of materials. the ingress or egress of water must be reduced to a minimum. thus relieving the pressure on the joints above. WATERPROOFING Licensed copy from CIS: URS. In extreme cases a true estimate of these final costs of caulking and sealing a tunnel could prejudice the use of one more suitable method of lining for the ground conditions as against another less suitable lining. In similar conditions a bolted concrete lining may require not only sealing at t h e joints. given in Table 13. For tunnels carrying raw water and for sewer tunnels. as used in Germany. Figures of the quantities of water flowing into a number of c o n ~ p l e t e dtunnels. consequently temporary measures may be necessary in the vicinity of this work. For railway tunnels dripping water or dampness may interrupt t h e signalling or electric circuits and thus all joints must be adequately sealed above the track level. The caulking cormpounds are mainly rigid ~naterials. the joints in the invert (ie below roadway or track) may be left uncauked. The several methods commonly used for permanent waterproofing measures are discussed briefly in the following sections. however. will give the driest tunnel in waterbearing strata. No material has yet been used successfully with flexible characteristics for use with articulated linings. will give a similar satisfactory dry tunnel. For road and cable tunnels and rail tunnels. . This may not. from Brunel's Thames Tunnel onwards. but also the sealing of hairline cracks and other cracks present in the lining following construction. new techniques of sealing joints are developed comparable results may be obtained. These figures.9. 04/03/2015. while for tunnels carrying filtered water supply there is an evident need to avoid contamination. Uncontrolled Copy. Many of these cracks or other small holes in the caulking may seal themselves in time due to the deposition of calcite which forms as a result of water leaching lime from the cement grout. There is thus frequently a law of diminishing returns in relation to the standards of watertightness. be economically possible in water-bearing ground and consideration should always be given to the tunnel use. When the ingress o f water before caulking is small and adequate pumping capacity is available. although welded steel joints. The cost of caulking o r otherwise sealing a tunnel may represent up to 10 per cent of the total cost of a tunnel and remedial measures may be even more expensive. In some cases the acceptable inflow of water in the invert may be several times that from the upper part of the tunnel. there must be no dripping water in the main area of the tunnel. URS Infrastructure. confirm that generally a tunnel lined in cast iron will give a drier tunnel than one lined in concrete segments. which refer t o a relatively small number of tunnels in varying ground conditions. where track circuits are used for signalling. Specifications often require that a tunnel should be completely dry. especially when additional waterproofing measures are being discussed. show the very large differences between tunnels in similar ground conditions. however. which are costly. Visible issues of running or dripping water are usually unacceptable but in many instances. The additional cost of sealing the ingress of a small quantity o f water may therefore be far greater than the benefits obtained. O Bolted cast iron Year 1963 52-68 Year 1973 76 40 Dart ford Chalk. Leakage into tunnels * Date of completion Internal diameter Type of lining Water flow l/m2 /day x 1o-2 Approximate max. mottled clay 1901 3.6 Bolted cast iron Clyde Sandstone boulder clay.8 to 6. Bolted concrete 1242 55 Top half of tunnel 540 x l/m2/day. peat 1963 9.5 Expanded cast iron.45 Bolted cast iron Blackwall Ballast. . bottom half 3240 x lo1 18 17 25 l/m2/day. Uncontrolled Copy. expanded concrete. silts and sands 1963164 9 .58 Bolted cast iron Rotherhithe Clay. 04/03/2015. sand and gravel 1908 8. URS Infrastructure. head of water at the crown m Tunnel Strata Greenwich Footway Tunnel Ballast.5 Bolted cast iron 76 21 LTE Victoria Line Mainly London Clay 1969 3. Mudstone and Lirnestone 1973 3O . London Clay 1961-67 8.6 to 120 40 Thames Cable Chalk 1970 . 3O Bolted concrete *540-3240 46 Severn Cable Sandstone. gravel. bolted cast iron 0.TABLE 13 Licensed copy from CIS: URS. lead is now only used for a relatively small proportion of tunnels in waterbearing ground.1 Grouting Licensed copy from CIS: URS. Where the material is used to seal joints in pipes it has been shown to withstand ~ . In waterbearing ground there may be a need for a quick setting grout. Uncontrolled Copy. For linings with machined longitudinal and circumferential joints. Cement based caulking compounds generally have only a small degree of flexibility. For a small number of cast iron lined tunnels in very dry conditions cement mortar pointing was used. bentonite or other gelling agents. 9. T h s process has been used a great deal in the United States b u t has seldom been used in the United Kingdom. acting as a rigid wedge to prevent the lead springing. has been used additionally t o fill the remainder of the joint. In a few instances in the United Kingdom. are costly and if the rings are staggered.2 Lead caulking Lead caulking has been used in conjunction with cast iron linings since the nineteenth century. under high water pressures. pulverised fuel ash. 9. . in several stages. In a number of instances pea gravel has been injected behind the lining which. with gelling characteristics. the number of block joints is doubled. as they are called. although tedious will help considerably to prevent the ingress of water.2 cement mortar pointing is occasionally used for cast iron lined tunnels in dry conditions.3 Cement based caulking compounds Cement based caulking compounds are mainly used for caulking concrete segmental tunnels although as discussed in Section 9. These block joints. apart from the Mini Tunnel system and a number o f trial lengths of tunnel. for tunnels in most types of ground. The lead caulking in the circumferential joint is liable to spring if slight movement occurs and therefore rust. that is break joint. if adequately compacted in t h e crown. the amount of which varies between products. Grouting is mentioned albeit briefly here as it is the first waterproof barrier of the tunnel. which must be of uniform size and rounded. Water is then added so that the cement sets and hardens forming a tight joint. Systematic back grouting. The rust while dry remains dormant but it becomes active when a leak occurs and swells sealing off the leak. material will take movement caused by small thermal expansion and conwater pressures up to 7 M N / ~The traction b u t only slight articulation of the joints. can be grouted for long lengths of the tunnel in one operation thus reducing considerably the number of 'cold' joints in the grout and the number of grouting operations. will reduce settlement of the ground on t o the lining. The material has a very long life. 19). which is packed into t h e joint using a caulking tool and hammer. 04/03/2015.9. Various grouts are available which use combinations of ordinary Portland cement or rapid hardening cement. The pea gravel. which give a large range of strengths and gelling times for different conditions. The sealing may not be 100%effective because rust caulking needs workmanship of a high standard which is not always obtainable. URS Infrastructure. With the introduction of cement-based and other caulking compounds and the increase in material cost. and additives including long chain polymers and accelerators. a mixture of iron filings and sal ammoniac. the lead caulking is carried out a t the internal face of the flange while with unmachined circumferential joints it is carried out towards the back of the joint behind the bolts (see Fig. excessive variation in the size of the pea gravel has prevented the grout from successfully sealing the tunnel. which will not be easily diluted or washed out by the inflow of water. In the United Kingdom pea gravel of spherical shape is often difficult to obtain and this may partly be the reason for the lack of use of this method. The majority o f tunnels are caulked with an asbestos cord impregnated with special cement based materials. although this large and controversial topic has not been covered in detail in this survey. In this latter case a considerably thicker caulked joint is required at each corner with the lead brought up to the front of the joint at each longitudinal joint to obtain a seal with the longitudinal face caulking. however. 9. may open up the leaks. Difficulty also exists in ensuring that no excavated material gets lodged in the joint. The circular duct so formed between two rings was grouted with a bentonite cement grout. When the joints are not damp pre-watering may be necessary with certain compounds. Uncontrolled Copy. The rubber bitumen may be cut with a knife or extruded and is easy to install. When large water leakage occurs in the joints the method of caulking the ring should be arranged t o channel the water t o one location of maximum discharge. has been used in both concrete bolted and smooth bore segments. The materials used to date. 04/03/2015. Expanded linings usually have more joints and thus more movement at the joints than bolted linings so that if they are caulked with rigid materials soon after erection. Trials have been carried out during the construction of several tunnels with expanded linings during the last 10 years to obtain a flexible caulking compound which can be easily applied in the tunnel environment. polyurethane and polysulphide. occasionally with running water. A final seal with a cement based compound is. based generally on epoxy resins. which may be reinforced with fibre. leaks may develop at the joints. These compounds will allow only slight flexibility and therefore cannot generally be recommended for articulated non-bolted linings unless the caulking is carried out at the end of the drive when the short term squatting of the lining has occurred. however. Rubber bitumen strip. probably only 20-50 years on account of ageing and thus caulking of the internal groove is essential for the long . For this material to bond satisfactorily the surface must be dry and clean. Other cement based caulking compounds commonly used incorporate mixtures of cement. is fairly soft and will squeeze under load. especially in the invert. This is an area where further research is necessary. The long term squatting. The weaker grouts were more flexible than the stronger ones but the success of the system is difficult to ascertain due to the amount of condensation in the tunnel.5 Sealing strips Various materials have been used in the longitudinal and circumferential joints of tunnel linings which compress and may incidentally reduce the concentration of loadings along the joint. In one of the contracts using the Don-Seg linings a few rings were cast with a semi-circular chase in the circumferential joints. These trials have not been generally successful and the conventional cement based compounds have later been used for the main lengths of tunnel t o prevent the ingress of water. during erection of the ring. The service life is. still recommended. have proved successful in laboratory trials. It is slightly tacky and bonds to the concrete under pressure. however. In some cases it may be necessary t o use a quick-set cement as a temporary seal to avoid leaching out of the cement prior t o setting. bituminous felt is normally used for the latter purpose but this does not give an adequate seal between segments. Asbestos cement materials may be packed into the back of the joint to obtain an initial seal followed by a permanent seal made with one of the other cement based compounds. even several years after the tunnel was complete. however.4 Flexible caulking compounds The caulking compounds discussed. 9.above are basically rigid materials with a small degree of flexibility. additives and proprietary waterproofing compounds.Licensed copy from CIS: URS. they have not proved successful. as discussed in Chapter 13. which may be as large as that for the short term. oven dried quartz sand. although deforming under load. Various grout mixtures were used. With all cement based caulking compounds the joints must be thoroughly cleaned of all dirt and dust. and often difficult to clean adequately. giving a seal between the segments. ground silica. where the joints are often wet. For bolted concrete linings. URS Infrastructure. In many instances a considerable amount of costly preparation work is necessary t o clean the caulking grooves and to divert the water. In a tunnel environment. The gel grummet. which compresses under the shove force from the shield forming a seal. however.6 Grummets For bolted cast iron and concrete linings grummets are commonly used to seal the bolt holes when the caulking of the flanges is carried o u t at the inside face. . however. Recently the oyster grurnmet has been used with a bolted concrete lining when a supply of gel grumn~etswas n o t available. plastic. as used in Germany. The grummet is compressed when the bolt is tightened thus forming a seal between the washer. A satisfactory seal was obtained. entailing precise alignment of segments and adjacent rings without the use of packings. the gel grummet and the oyster grummet (see Fig. or where no caulking groove is provided. 04/03/2015. Alternative sealing methods for concrete linings include the fixing of straps or bandages of aluminium. URS Infrastructure. A sealing strip recently introduced incorporates a polyethylene strip at the back of the circumferential bolts in the concrete bolted ring. The sealing o f joints with neoprene sealing strips. the bolt and the flange of the lining. is effective but expensive. The bolt holes for the concrete segments are not countersunk and thus to contain the grummet a dished washer was used. However. Uncontrolled Copy. These methods are. water.term. Licensed copy from CIS: URS. and are 12 m m t o 15 mm thick depending on the diameter of the bolt. epoxy resin and fibre glass or similar material to the face of the joint which seals the joint or leads the water to the invert o f the tunnel where it is collected in the drainage system. The grummets are available for bolts with diameters of 19 mm to 5 1 mm and are colour coded according to size. 9. the rubber bitumen emulsion and cement compound used with the Wedge Block lining does help to seal the joint. normally confined t o remedial works if the initial caulking is not completely successful. To avoid this relaxation the geometry of the countersunk bolt hole and the chamfered grummet must be matched so that when the bolt is tightened the material does not flow between the washer and the flange. The bolt holes in the flanges are countersunk at 45' t o a depth of 6 m m and the grummets are chamfered on both edges. The grummets which are placed between the washers and the flange are available in two forms. Where the material flows between the flange and washer some relaxation of the bolt load may occur subsequently but there will be a permanent seal. If the bolts are retightened. The grummets are available for diameters of bolt holes of 26 mm to 52 mm and for circular and elongated bolt holes. The painting o f joints with bitumen has little effect on the quantity of water entering the tunnel. which is manufactured from pure sisal hemp impregnated with a mineral gel. Red lead may be used with the gel grummets when the external water pressure is high. alkali and mild acids. When the bolt is tightened beyond a certain limit the material flows into the bolt hole around the bolt and in most instances between the washer and t h e flange t o form a watertight seal. the seal may be lost. 19). has been used for sealing bolt holes since t h e last century. The oyster grummet which is used mainly in'cast iron and steel lined tunnels is manufactured from low density polyethylene which is impervious to oil. 2 m internal diameter Mini Tunnel which has increased rates of progress for this tunnelling system in these types of ground conditions. the ground conditions and the type of primary lining. the extent of preventive maintenance and. to a smaller handexcavated specified diameter. increasing to 10 to 30 minutes for the medium diameter expanded linings.5 m can be erected by hand in 3 to 5 minutes. however. In practice many contractors will tender for a 1.the back up system for the delivery of the lining to. For hand shields the rate of progress may increase to the sustained average over a length equivalent to some 2. These factors will also have a large bearing on the contractor's method of excavation in (b) below. the distance between shafts. The diameter of the tunnel dictates the accessibility of the face and thus the rate of removal of the excavated material. For tunnels below 2. several fold. In comparison the 1. with similar methods of excavation and lining. generally increasing with diameter. the shift system. marls and weak rocks for the 1. for mechanical methods of excavation. by hand. Rates of progress for driving tunnels vary considerably from scheme to scheme and are dependent upon two main groups of factors: a) Those dictated by the design of the tunnel which include the diameter and the length of the tunnel.5 m to 3. as the rate of progress can be increased. URS Infrastructure. Many of these factors are directly or indirectly concerned with the lining and these are briefly discussed in the following paragraphs. With increase in diameter. however. Above 2 m to 3 m diameter the rates of progress for similar conditions generally decrease. The rates of progress for tunnels of 2 m diameter and below. The length of drive has a considerable effect on the rate of progress.5 to 5. TUNNEL CONSTRUCTION 10. smoothbore or cast iron linings the time for erection of a ring will vary from 20 minutes to 45 minutes. at a very competitive cost. For tunnels of diameter up to 3 m with conventional bolted concrete.8 m or 2 m diameter tunnel as an alternative. Uncontrolled Copy. . more elaborate mechanical methods of erection become practical and reduce the time of erection of the lining.10. A particular case is the 2. The type of lining used in a tunnel and the method of erection will affect the rate of advance of the tunnel. the face.3 mMini Tunnel and the expanded DonSeg and Wedge Block linings of diameter up to 2. the actual down time for the shield or tunnelling machine.1 Rates of progress Licensed copy from CIS: URS. At the commencement of a drive there is a gradual build up in the rate of progress as the miners become familiar with the tunnelling system and the back up equipment is installed behind the face.0 times the diameter 140. roadheader and similar machines have been used for tunnels in cohesive materials and soft rock for diameters down to 1.while for full face machines it may be 2 to 3 times the length of the travelling platform. 04/03/2015. the mining gangs and the target payments. with congestion generally more acute as the size decreases. roadheader or full face machine .0 m the linings are normally erected by hand as there is little or no increase in the speed of erection by using mechanical aids. will differ little. and the removal of the excavated material from.0 m to 1. Hand excavation has traditionally been used for tunnels below 2 m diameter. Recently. the method of erection of the lining.5 m diameter Wedge Block lining. A full face machine has also been introduced recently for stiff clays.8 m diameter and below with greatly increased rates of progress139. b) Those dictated by the construction system which include the chosen method of excavation with or without a shield. where very high rates of progress have been obtained. URS Infrastructure. and for a smali number of drives with mainly expanded linings b u t with lengths o f bolted cast iron linings in poor ground conditions. 2 1 shows the spread of maximum sustained rates of prosess for the full face and for the roadheader machines with expanded concrete or expanded cast iron linings. the graphs for the hand excavation and the hand shield drives are very similar. between 40 and 5 0 running tunnels of approximately 3. A comparison of the maximum sustained rate or progress over the best four week period and the average progress for the drive showed very variable results and no general trend.5 km and 1.85 m internal diameter and with a large variation in length were constructed with different forms of excavation and types of lining. organisation and efficiency for the delivery and removal of materials and whether the particular drive is on the critical path of the construction programme.85 m internal diameter tunnels. If this had been reduced to say 6 weeks the break even distance would have been more than halved. In order t o show the effect of the type of lining and the method of excavation on the rate of progress it is necessary t o have a large number of drives in the same type of strata. of up to 1500 m in length. a roadheader in a shield and a full face mechanical shield. With a full face . 04/03/2015. up to 300 m . however. Fig. 22.5 km to 2 km the roadheader machine will probably be more economical than a full face machine. The process o f driving a tunnel incorporates two main operations . with expanded linings. dictate the maximum sustained rates of progress. This is a very high figure but would be influenced by a relatively long period of 1 2 weeks before the full face machine reached its peak rate of progress. shows a faster sustained rate of progress. The results showed that for drives up to 1. In this particular case the use of a roadheader machine increased the rate of progress only marginally on that for the handshields. with expanded concrete o r cast iron linings and a limited number of roadheader or excavator machine drives. the contractors site set up. In particular those factors most relevant probably include t h e availability o f miners. The full face machine drives. based on t h e best 4 week period o f each drive. the rates of progress for a mechanical shield may be 3 to 4 times that for a handshield a n d for a roadheader machine 2 t o 3 times.5 k m the handshield was quicker overall for the construction of the drive. The rates of progress for these drives have been analysed together with additional data from the more recent LTE Fleet Line and Piccadilly Line Extension to Heathrow Airport. In most cases these two operations are consecutive but in certain circumstances they are carried out concurrently with a consequent increase in the rate of progress. The graphs show how the maximum sustained rates of progress increase with the length of drive tending towards a maximum. Uncontrolled Copy. than that for t h e full face machine. 2 1. A similar exercise in the comparison of the rates of progress for different methods of excavation was carried o u t b y the MWB in the late 1960's based o n information from two of their contracts with handshields. up t o drives of 1200 m in length. I n general. w i t h expanded concrete linings are based o n Fig. There are many factors which affect the average rate of progress a n d therefore the difference between t h e ratio for similar schemes.the excavation and removal of the material and the erection o f the lining. For the LTE Victoria Line. Fig. plotted against the length of drive in metres for the various forms of excavation and types of lining. The plot of the ratio of the two rates of progress against length of drive is given in Fig. For drives between 0. For the shorter drives. which is based on a small number o f drives. The maximum sustained rates of progress increase generally with increase in length of drive although for drives above 2000 m in length the rates o f progress have levelled off and there is a tendency for a reduction in the rate of progress probably due to t h e increased travelling time t o the face. The curve for the roadheader machine. 2 0 shows the maximum sustained rates of progress. of up to 1500 m in length. for the 3. The method of excavation for the other three types of drives.Licensed copy from CIS: URS. Licensed copy from CIS: URS. Uncontrolled Copy. For the LTE 3. When a tunnelling machine is used. The number of tunnels constructed in rock in the United Kingdom is relatively small when compared with those in soft ground. if no thrust force is required. evenly split between the excavation and the erection. These are based generally on the maximum sustained rates of progress for the drives which may be 1. based on a large number of schemes. with or without a shield. which is required for the bolted and former ring types of lining. Typical rates of progress for drives are difficult to give as two tunnels are seldom the same and different contractors will tender and obtain different rates of progress. the 15 shift system comprises 8-hour shifts. weakening etc. When a shield is not used the two operations are normally consecutive. The rates for the medium and large diameter tunnels cover schemes over the last two or three decades and may therefore be underestimated. In practice. It should also be explained that many of the records quoted for the maximum weekly progress are for a seven day week rather than the conventional five day week. but the space available for the erection will be restricted. overlapping of the two operations is possible for medium diameter tunnels but space is inadequate to permit this in small diameter tunnels.3 to 2 times the average rate of progress. the excavation is normally the longer of the two operations accounting for 213 to of the cycle time and thus a few minutes saved on the time for the lining erection is of little consequence. They are therefore only a guide to the range of maximum sustained rates of progress. for the two operations to be carried out concurrently. which are well above the sustained progress and no comments are usually made about the following shifts or week when the miners probably reduced their output. URS Infrastructure. may be carried out concurrently with the two main operations or at the end of the shift. For the design of ancillary and back-up equipment. The designation of the rocks is based on the classification given in Table 1 in Chapter 3 and could be subdivided into further groups based on the discontinuity characteristics. the miners on account of the piecework payment system complete the work that will give them their required weekly target wage one or two hours before the official end of the shift. When a roadheader or similar machine is used in the face it may be possible. When a tunnel is excavated by hand. The 10 shift system normally consists of 12-hour shifts or 10-hour shifts plus two hours for maintenance requirements. reduced to some 20 minutes to 30 minutes for a full face machine with an expanded lining. In very poor or hard . The target for this piecework is therefore critical to the rate of progress attained. Table 14 gives a general guide to the rates of progress for tunnels in a variety of strata. the cycle time may be 2% hours for a hand shield with a bolted cast iron lining. The third operation of grouting.mechanical shield the machine is thrust forward on the previously erected ring and thus the two operations are carried out consecutively. In the United Kingdom a five day working week is normally worked with 10 or 15 shifts. the excavation will normally be the shorter operation and a few minutes saved on the lining erection may add a ring or two to the number erected in the shift. The important statistics for a tunnel drive are the average progress based on the complete drive and the maximum sustained weekly progress which is often taken as the maximum based on a four week period. however. In general however rates of progress for tunnels up to 3 m may be 3 to 8 rings a shift for hand shield drives depending on the ground conditions. it is clearly necessary to consider the anticipated peak rates of progress. for example. 04/03/2015. For the Wedge Block expanded lining the cycle time for a hand shield may be 1 hour while for a full face machine it is 10 to 12 minutes.85 m internal diameter running tunnels. depending o n the availability of miners and the work involved. however. depending on the ground conditions. The rates of progress quoted in the technical press are often misleading as they are the maximum progress attained for one or two isolated shifts or for a particular week. For hand excavation with a shield. The time to erect a shield varies considerably even for the same diameter shield. Where such access is not available 2 t o 3 weeks may be necessary for a small hand shield. 4 and 5. depending upon the type of lining. The time to dismantle a shield is often longer than expected and in many cases is n o t o n the critical path for the contract. In general there is a large range of times.1. 3 m t o 6 m.TABLE 14 Typical ranges of maximum sustained tunnel driving rates (m/week) Tunnel diameter Ground type up to 3 m Soft Ground Drift. For small diameter hand shields where access is n o t limited and a large enough shaft is available the hand shield can be lowered down in o n e piece and be available for the commencement of the drive the next day or certainly within a week. if it is a long distance to the shaft or if the skin is left in place. 6 to 15 weeks may be required before commencement of the drive. For mechanical shields of less than 3 m diameter if ready access is available 1 to 4 weeks may be necessary b u t in difficult conditions 6 t o 8 weeks may be required.5 to 15 275 to 300 9 0 t o 180 3 0 to 6 0 45 t o 100 15 to 30 15 to 45 45 to 250 1 0 t o 60 Strong 15 to 6 0 15 to 70 10 to 7 0 Very strong and extremely strong 2 0 to 150 15 t o 100 10 to 60 Stiff t o Firm fissured clay with b o o m machine or hand excavation Rock Very weak t o moderately strong - rock this may be reduced t o one ring a shift. the chosen method of erection and how critical it is to the duration of the tunnelling cycle. Data are given in Appendices 3 and 4 on the time to erect the individual linings. URS Infrastructure. realistic figures are therefore difficult to establish.3 m 20-45 minutes 30-90 minutes 3-5 minutes . For larger diameter 6 to 12 weeks may be necessary. alluvium and glacial Licensed copy from CIS: URS. Examples of rates of progress have been included in the data given for a number of tunnels in Appendices 3 . For the range 3 m to 6 m. One third t o half the time t o erect is probably realistic but in many cases it has taken longer to dismantle than erect especially if access is difficult. These are summarised below: Bolted concrete and smooth bore linings up to 3 m Bolted concrete above 3 m Mini Tunnel 1 .O. For medium sized tunnels. 04/03/2015. the hand shield may take 2 to 1 0 weeks t o erect depending upon access and the size of the shield chamber b u t 3 t o 6 weeks is probably average. For tunnels above 3 m up to 6 m the maximum will vary from 1 to 6 rings per shift with a hand shield. Stiff t o Firm fissured clay with full face machine 15 t o 75 3mto6m 10 t o 7 5 6 m upwards 7. Uncontrolled Copy. For tunnels above 6 m rates of progress of 1 to 3 rings per shift have been obtained with hand shields. Uncontrolled Copy. Many tunnels are driven without full knowledge of the likely ground conditions which may vary from metre to metre and therefore some tunnellers are very conservative and specify forms of linings which have been well tried. the tunnel use and the secondary lining requirements.2. causing difficulty in the erection of subsequent rings although the bolts will support the ring. In practice. Although these linings have been used in very soft clays. 10.1 Bolted cast iron linings: These linings may be of grey or spheroidal graphite iron and are now generally used for road and rail and associated tunnels. have pioneered new types of lining which have markedly helped t o reduce the overall cost of tunnels.2 Suggested tunnel lining methods The several forms of primary linings and secondary linings have been discussed in Chapters 3 .2. This section summarises the conditions in which each form of primary lining should be used.2. 10. 6 The forms of linings are briefly summarised. They may be used also in strong rock tunnels where lining is required for safety or waterproofing reasons. In consequence only broad outlines are discussed in the following paragraphs. indicating the type of ground conditions in which they should be used. Table 15 gives a summary of these forms of linings with tunnel use and ground conditions and Table 16 the ground conditions for which each form of lining is suited.4 Grouted smooth bore concrete linings: These linings. but only in a few instances for water cable and sewer tunnels. 10. 5 and 6 while in Table 2 in Chapter 3 details are given of the general types of primary linings. where ground conditions can be accurately assessed. hand shield or mechanical shield driven tunnels in most soft ground or weak to moderately strong rock tunnels in conjunction.Expanded concrete linings 2. a rigid lining such as that provided by pipe jacking may be preferable and will be essential where the competence factor is less than %. Some engineers on the other hand. In soft ground tunnelling where the ground is not self supporting the rings should in general be grouted immediately after erection. they have been used to a small extent in other ground conditions which may not necessarily have been ideal for the requirements of the lining. 4 . where necessary.5 m Wedge Block 3.3 Bolted concrete linings: These linings are the main form of lining used in the United Kingdom for all forms of tunnels. 10. Grouting t o the crown will.4 m 4m-10m Expanded cast iron linings 4 m 3-5 15-30 15-45 15-60 1-3 15-30 minutes minutes minutes minutes hours minutes Licensed copy from CIS: URS. The linings may be erected in hand excavated.2. They may be erected in hand excavated.8 m LTE linings 5-10 m Bolted cast iron linings 2 m . erected o n a steel . however. 04/03/2015. and tolerate a wide range of ground conditions. If the ground is allowed t o come on to the lining the ring will squat slightly. The linings are quick t o erect and high rates of progress are obtained with hand or mechanical shields. 10. and for special and difficult sections of tunnel. Their application in grey iron for the 3. normally for sewer tunnels. Each tunnel must therefore be analysed on the data available taking into account technical and economic considerations. be difficult or impossible after squatting.85 m LTE running tunnels was not fully successful on account of the thin cross section of the lining. are used in hand excavated and hand shield tunnels and are. with compressed air or blasting. with the exception of the three segment Mini Tunnel.2 Expanded cast iron linings: These linings have only been used in grey iron although future application would probably be in spheroidal graphite iron due to its tensile strength characteristics. URS Infrastructure. The use of these linings has considerably reduced during the last 2 0 years and their main application now is where good waterproofing is required. hand shield or mechanical shield tunnels with the void behind the lining filled with grout. 04/03/2015. 2. Linings shown in brnckets may be used for the type o f ground but other forms may be preferred on economic grounds. the ratio of the overburden pressure to the water pressure is below an acceptable factor. Uncontrolled Copy. For water tunnels a steel lining may be necessary where for particular conditions. Co~icoursesetc. . waterproof Aesthetic waterproof (a) D ~ i f above t watertable Bolted Concrete Smooth Bore concrete Pipe Jacking Bolted Concrete Smooth Bore concrete Pipe Jacking Bolted Concrete Smooth Bore concrete Pipe Jacking Bolted Cast Iron (Bolted Concrete) Bolted Cast Iron (Bolted Concrete) Bolted Cast Iron (Bolted Concrete) Bolted Concrete Bolted Cast Iron (b) Drift below watertahle Bolted Concrete Pipe Jacking (Smooth Bore concrete) Bolted Concrete Pipe Jacking (Smooth Bore concrete) Bolted Concrete Pipe Jacking (Smooth Bore concrete) Bolted Cast Iron (Bolted Concrete) Bolted Cast Iron (Bolted Concrete) Bolted Cast Iron (Bolted Concrete) Bolted Cast Iron (Bolted Concrete) (c) Silts and clays Bolted Concrete Smooth Bore concrete Pipe Jacking Bolted Concrete Smooth Bore concrete Pipe Jacking Bolted Concrete Smooth Bore concrete Pipe Jacking Bolted Cast Iron (Bolted Concrete) Bolted Cast Iron (Bolted Concrete) Bolted Cast lron (Bolted Concrete) Bolted Cast lron (Bolted Concrete) (d) Very soft clays Pipe Jacking (Bolted Concrete) Pipe Jacking (Bolted Concrete) Pipe Jacking (Bolted Concrete) Bolted Cast Iron Bolted Steel Bolted Cast Iron Bolted Steel Bolted Cast Iron Bolted Steel Bolted Cast Iron Bolted Steel (e) Stiff fissured Bolted Concrete Smootli Bore concrete Expanded Concrete Expanded Concrete Bolted Concrete Smooth Bore concrete Expanded Concrete Bolted Concrete Smooth Bore concrete Expanded Concrete or Cast Iron Bolted Concrete (Bolted Cast Iron) Expanded Concrete or Cast Iron Expanded Concrete Expanded Concrete Bolted Concrete (a) Very weak to ~nodcratelystlong Bolted Concrete Smooth Bore concrete (Cast in. Passages.Licensed copy from CIS: URS.situ concrete) Bolted Concrete Smooth Bore concrete (Cast in-situ concrete) Bolted Concrete Smooth Bore concrete (Cast in-situ concrete) Expanded grouted Concrete lining Cast in-situ concrete Expanded grouted Concrete lining Cast insitu concrete Expanded grouted Concrete lining Cast insitu concrete Bolted Concrete Cast in-situ concrete (b) Strong Cast in-situ concrete (Bolted Concrete) (Sprayed Concrete) Cast in-situ concrete (Bolted Concrete) (Sprayed Concrete) Cast in-situ concrete (Bolted Concrete) (Sprayed Concrete) Expanded grouted Concrete lining Cast in-situ concrete (Bolted Concrete) (Sprayed Concrete) Expanded grouted Concrete lining Cast insitu concrete (Bolted Concrete) (Sprayed Concrete) Expanded grouted Concrete lining Cast in-situ concrete (Sprayed Concrete) Cast in-situ concrete (Bolted Concrete) (c) Very strong and extremely strong unlined (Cast in-situ concrete) unlined Sprayed Concrete (Cast in-situ concrete) unlined Sprayed Concrete (Cast in-situ concrete) unlined Cast in-situ concrete Sprayed Concrete Rock bolting unlined Cast in-situ concrete Sprayed Concrete Rock bolting unlined Cast in-situ concrete Sprayed Concrete Rock bolting Cast in-situ concrete Rock 1Jolting CROUND CONDITIONS SOFT CROUND clays ROCK Notes: I. URS Infrastructure. Smooth Smooth As primary lining or special profile As primary lining Smooth Aesthetic. TABLE 15 Suggested methods of lining tunnels Tunnel use Sewer INTERNAL FINISH Water Cable Underground railway High spced railway Road Pedestrian Subways. the segments being supported during the erection and prior t o grouting with longitudinal bars. The linings. 04/03/2015.TABLE 16 Preferred form of lining for a variety of ground conditions M 2 3 Type of lining ground conditions Licensed copy from CIS: URS. URS Infrastructure. in Bunter Sandstone. For the Mersey Kingsway Tunnels.used in very soft clays unless designs have been carried out t o prove their suitability. in ground that tends t o come rapidly onto the lining. should be grouted immediately to avoid progressive squatting from one ring t o the next. A few tunnels have been constructed in compressed air or with blasting although the latter is not generally recommended for use with this lining. Uncontrolled Copy. The linings should not generally be. SOFT GROUND (a) Drift above watertable * (b) Drift below watertable * (c) Silts and clays * (d) Very soft clays (e) Stiff fissured clays * * * * * * * 3c * * * * * * * * * ROCK (a) Very weak to moderately strong (b) Strong (c) Very strong and extremely strong Notes: Preferred lining shown by * * * x * * * * * former ring or on internal hoop bars. this form of lining was used. . and the Dartford Duplication Tunnel in chalk. the degree of watertightness therefore depends o n the surrounding ground conditions. which are quick to erect. 04/03/2015. sprayed concrete may act as a permanent support. 10. Uncontrolled Copy. Spheroidal graphite iron will probably be preferred for future tunnels of such type. The linings should n o t generally be used in weak t o moderately strong rock. This form of lining may be expanded against the rock and grout used t o seal the voids. shoving against the recently cast concrete lining.10.2.10 Cast in-situ concrete linings: These linings have been used for sewer. the presence of water and other factors. are always used in association Licensed copy from CIS: URS. 10.3. a shield has been used. although for a small number of road tunnels. future tunnels will probably be constructed in spheroidal graphite iron.2. or shotcrete and rock bolts.5 Expanded concrete linings: These linings. conditions o f rock jointing. with or without sprayed concrete. where the temporary rock loads are high or are a large percentage o f the design load unless the lining is cast close to the face. 10. Ground support may be carried out with colliery arches and laggings.7 Steel liner plate linings: These have been used successfully as temporary support for small diameter tunnels as a n alternative t o timber headings and their application in this connection will probably increase.2.1 1 Sprayed concrete or gunite linings: These linings normally serve as ground support in weak to strong rock. with a hand or mechanical shield and are suitable for firm and stiff clays. 10. a hand or mechanical shield may excavate a smooth profile with only a small amount of overbreak. Fabricated steel bolted segments are used above and below openings in cast iron tunnels and for special sections.6 Expanded grouted concrete linings: In weak to moderately strong rock.2. As temporary linings they may be used as laggings for colliery arches in weak t o strong rock and. as secondary linings in aggressive ground conditions. water road and rail tunnels in most rock conditions. Expanded steel linings have been used for a number of medium and large diameter tunnels in London Clay where large eccentric loads were expected and where the ground had t o be supported as quickly as possible.2.8 Steel circular membranes: These are normally used in high pressure water tunnels where the depth of overburden is insufficient to take the hydrostatic pressure in the tunnel. is possible but grouting or "pugging up" may be necessary. with little overbreak.2. In sound competent rock and around tunnel portals rock bolting may be used as a permanent support. The expanded concrete linings are more difficult to waterproof than bolted rings as no effective flexible caulking material is yet available. 10. 10.2.2. . The lining is normally cast well back from the face or on completion of a drive. but preferably in cohesive material. here again. An alternative bolted or grouted lining should always be available for use if there is a risk o f encountering difficult ground.1 2 Rock bolting: Rock bolting may be used as a temporary support in weak to strong rock.9 Bolted and expanded steel linings: Fabricated steel bolted linings have been used for tunnels in preference t o grey iron linings where large forces have been exerted from the shield during construction. In mining areas short lengths have been used as flexible internal primary linings as discussed in Section 10. 10. rail and water tunnels. the scheme being selected in relation to ground loads. They may be used in conjunction with rock bolting.2. Their use has been mainly for road. Their application in weak to moderately strong rock tunnels may be possible if a smooth bore excavation. although they will probably be extended in the near future to sewer tunnels. when galvanised or protected with bitumen. URS Infrastructure. In sound strong to extremely strong rock. where they also prevent ravelling and weathering of the rock face. If techniques can be developed for erecting and partly expanding the lining within the tail of a shield their use may be extended t o other soft ground conditions. All circumferential joints must be designed to take the maximum anticipated movement. aggressive nature. URS Infrastructure. however. in particular next to the compressed air pipes.4. The cement chosen for concrete linings should be in accordance with Table 49 of the Generally.3 Special ground conditions 10. 04/03/2015. As the linings are erected the compression of the jointing material must be accurately carried out to allow for the future tension or compression without opening or closing the joint completely. such as cast iron or brick. Faced with these conditions the first step is to attempt to change the alignment of the tunnel. described in Section 5. however.as the extraction progresses. c) a flexible steel r i e r plate lining over the areas where maximum differential settlement is anticipated. in the presence of water or when jacking too close to the ground surface.1 Aggressive ground conditions: Where tunnels are constructed through soils or groundwater of an Licensed copy from CIS: URS. the full implications of the use of the cement must be understood and adequate precautions taken in the casting and curing of the segments.3.8 per cent and a maximum horizontal movement between adjacent rings of 5 mm without decompressing the foam joint. If acid or alkali attack is also likely the lining may deteriorate. Uncontrolled Copy. The possible linings are: a) the Spun Concrete Extraflex lining.13 Pipe jacking: The use of pipe jacking is increasing not only for short but also for longer tunnels. The use of high alumina cement for primary linings in aggressive conditions is not generally recommended . both of these conditions are likely to accelerate the conversion of high alumina cement. and water is often present. An internal lining of steel or fibre based material may be used which is free t o move inside the primary lining. only Portland cement or sulphate British Standards Institution Code of Practice CP1 resisting cement should be used for precast primary linings. The technique may be used in most drift materials. horizontally or vertically.with the bolts only partly tightened to allow for the required compression and expansion of the joint. particular attention must be paid to the lining. forms of lining other than concrete may be necessary.10.2. During the construction of a tunnel the temperature is generally high.2 Mining areas: In mining areas where the further extraction of coal or minerals is foreseen the lining must be capable of accepting the temporary settlement wave. the factor of safety of the concrete lining in place is high and thus some reduction in strength will not affect the adequacy of the lining.although there may be occasions when its use will be necessary. extent and degree of movement anticipated. One of the following alternative linings may be selected but each scheme should be considered separately on the nature.6 and Appendix 4 which has a cellular rubber strip with neoprene skin in the joint and locating pins which will allow a horizontal strain of 0. . to avoid traversing the area.3. problems may arise in loose ground. A thin external lining of fibre or resin base material may serve either t o protect a structural concrete lining or to provide a structural lining in its own right. If the chosen alignment cannot be altered. Water and soil samples will establish the sulphate content and the pH value. However. In general. 10. b) a bolted concrete lining with a foam type seal between the circumferential flanges . 10. This will entail both compression and tension of the circumferential joints. The design of these joints is briefly discussed in Section 8. for the sewer and water market. any additional costs of the smooth bore lining being offset b y the reduction in excavation and the omission of the secondary lining.Licensed copy from CIS: URS. the work force was scattered around the country. which was very low at the end of 1973 and early 1974 on account of the economic climate. much of the work force was based on London but. Uncontrolled Copy. in t h e North East o f England. always a fluctuating level of demand in each area from year t o year. COSTS The costs o f driving tunnels increased considerably in 1974175 mainly on account of the general inflation and the decreasing demand for tunnels. For a particular diameter the variation due to ground conditions may be nearly twelve-fold for large diameter tunnels and 3 to 5 times for small and medium diameters. Fairly accurate costs can be obtained from the Bills for the total cost of constructing a tunnel broken down into unit lengths but the accurate subdivision. around Edinburgh. 25 shows a graph of the spread of cost of sewer tunnels at January 1976 prices. and in the Midlands. However. A number of different methods are used b y contractors to spread their costs amongst the several items in the Bill o f Quantities. The time taken to erect the lining compared with the excavation for the tunnel has been discussed above. For sewer tunnels the cost of a bolted concrete lining with a secondary cast in-situ concrete lining will normally be similar t o a smooth bore concrete lining with no secondary lining. The unit cost of the lining in the Bills will normally only contain a small element of contractor's profits or oncosts. The cost of tunnels varies with the diameter and the ground conditions. the local government reorganisation. For a bolted concrete lining in LondonClay the range of the division of cost of a small diameter tunnel is as follows: .of varying length and size. thus necessitating the movement of the work force across the country t o other areas. i n t h e vicinity of t h e Tyne and the Tees. b u t mainly in the vicinity of the large conurbations.of these costs into excavation.2. 2 4 shows how between 1950 and 1976 the lower end of the road tunnel construction costs remained fairly constant143. In the latter part o f 1974 the market for this latter sector picked up as discussed in Section 3. Fig. In addition on account of much o f the new work being located in a small number of areas the extent of these increases in costs differed from locality to locality being in some instances between 2 0 per cent and 5 0 per cent above those let twelve months previously.4m per k m for a tunnel in London clay to &24m or more per km for a tunnel in waterbearing ground 142. This method of presentation does not show the technical advances which have been made and which may have reduced the cost of tunnels substantially in real terms. Fig. high increases in labour cost and. 23 shows the total cost of road tunnels since 1956 updated to January 1976 costs. which will give a guide t o present day costs. spread over t h e country. Fig. There is however. considerable variation may exist from tunnel tender prices. In the mid 1960's. This is well illustrated b y the cost of road tunnels which at January 1976 costs may vary from &2. and it would therefore be possible t o carry o u t a distribution of the cost on a time basis although it should be born in mind that in many instances the two operations overlap or are coincident. 04/03/2015. In t h e last few years the centre of gravity of this work force has moved northwards and eastwards. 11. there are now large concentrations of work in the South East of Scotland. as this is based o n up dating old prices. Over a hundred tunnels are under construction at any time . with the increased use of tunnels for the sewer market and the consequential increase in labour rates in the provinces. URS Infrastructure. erection of the lining and grouting is much more difficult. until the early part of the 1970's when it increased with the recent rapid inflation. It is not therefore possible to subdivide the costs to give the value for the erection of the lining but only the lining cost as a percentage of the whole cost. 45 m internal diameter bolted reinforced .1. a number of factors must be taken into account. The actual tender price may vary slightly from the budget price. With expanded linings. however. Uncontrolled Copy. consequently the cost of the lining may increase to between 15 and 35 per cent of the total cost of the tunnel. which generally give a higher unit cost than for similar standard linings. 04/03/2015.1 9 7 6 ~ ~All bore linings on request which will allow for transport to the site. It must always be borne in mind that at any particular time there are variations in price to meet demand. The cost of a complete ring of moulds may be between £400 and £2500. When discussing the unit cost of special linings. For tunnels with cast iron linings the percentage of the cost of the lining will be higher rising t o 50 per cent when excavation costs are low. Licensed copy from CIS: URS. 26 shows a typical graph of the variation of cost of a 2. complexity and number of segments in the ring. 11. although there are variations within the whole range. as supply conditions may be different at the time of tender. erection and grouting Caulking Secondary lining The cost of compressed air may add a further 20 per cent to the cost of the tunnel. In the 1970's. however. As a rough guide the unit cost of linings at January 1976 prices falls into the following ranges: Type of lining Bolted Concrete Linings Smooth Bore Linings including loan of erector former rings Cost per m3 of concrete in the lining including reinforcement if present £100-£ 150 £80-£130 The smaller diameters of lining are normally more expensive than the medium diameters. depending on the size. the unit costs increased in step with inflation and have doubled in the last three years.1 Precast concrete linings: The unit costs of precast standard linings remained fairly constant during the 1950's and 1960's mainly on account of the improved methods of casting.Lining Excavation. only a small number of which have been used in the last 10 years. rates of progress may be high and therefore reduce excavation costs. reduced overheads. URS Infrastructure. The three main components of concrete lining production are: a) moulds b) reinforcement c) concrete The majority of segments for the standard bolted and smooth bore linings are cast horizontally and the cost of the individual moulds will be in the range £100 to £250.1 Unit cost of linings 11. manufacturers will supply budget prices for bolted or smooth concrete ring for the period 1 9 5 2 . and of increased production. These moulds are used an . Fig. are spread over only a relatively small number of moulds. which can be taken as a standard.economic number of times. since a ring with a large number o f segments may require n o reinforcement and one with a small number may well require reinforcement. When a new special lining is designed there will be considerable developnient costs which. The principal use of t h e vertical method of casting is for the Wedge Block lining. These costs will vary from lining to lining and will be particularly high where close tolerances are specified. before choosing t h e final design. URS Infrastructure. 04/03/2015. in general. Spheroidal graphite iron has been introduced over the last few years and used mainly in small quantities therefore no long term cost statistics are available. When grout o r other radial holes are required the segments may only be cast in pairs. Standard segments are generally cast of concrete of characteristic strength of 40-45 MN/mZ . or any other expedient to allow the steel to be omitted. in the range of £1. . such as joint formers. including the cost of the extra excavation. This compares with only a doubling or trebling in the cost of the standard precast concrete lining. The cost of reinforcement in a tunnel lining is generally higher than for other reinforced concrete structures o n account of the short lengths of steel used and thus the increase in bending and fixing costs per tonne of steel. rather than a special lining and for which the cost of the moulds represents only 1 per cent to 2 per cent of the cost of the lining. For many special linings. These are very high percentages and thus in the design of a lining. The costs of moulds and reinforcement discussed above are of course interdependent. fours or sixes with corresponding reductions in the cost of the moulds and in the space required for casting. For solid segments with plane o r tongue and groove circumferential joints the segments may be cast vertically in pairs. 11. but for special linings cast at a manufacturer's yard an additional cost will be added on account of production difficulties with two types of concrete. In general the total cost of a ring of moulds will increase with the number of segments in the ring and thus the cost of the concrete moulds for a ring of 10 segments may b e two thirds of the cost for a ring of 2 0 segments. considerable savings could have been made.2 Cast iron linings: During the last decade the cost of cast iron linings has increased considerably and in 1 9 7 6 was four t o five times the cost in the early 1960's. may be used 1000 or more times. for handling if not for the loading in service. site cast segments this will only increase the cost of the lining by the increased cost of t o about 55 M N / ~ For concrete. comparable estimates should be made between reinforced and unreinforced segments. In a number of recent cases the moulds have been used only 100 to 150 times.1. Uncontrolled Copy.25 t o £lO. All the development costs will have been included in the initial contract for each individual diameter and thus the mould cost per ring of tunnel lining will be fairly small. In a number of recent schemes the cost of reinforcement in lining has been between 2 0 per cent and 5 0 per cent of the total cost of the lining.representing some 5 per cent t o 1 0 per cent of the cost o f the ring. and the increased cost of casting the segments. Licensed copy from CIS: URS. and thus the cost of the moulds has represented 25 per cent t o 35 per cent of the cost of the lining. The main increase has been in the material cost of the cast iron which accounts for approximately 6 0 per cent of the total cost of the lining. The cost per tonne of reinforcement will vary in each case but will b e in the range of £250 t o £350 at January 1976. it is found expedient to design for higher stresses and thus the characteristics strengths are increased ~ . When calculating t h e cost of moulds per ring of tunnel lining the main factor will be the number of uses of each mould. usually about 250-350 and individual parts. Thus if the number of uses has been doubled at 2 0 0 t o 300. The economic number will usually be between 250 and 350 but for many special linings the number of rings of moulds and therefore the number of uses will be dictated by the rate of production required for the tunnel driving. 3 Secondary linings: There are large differences in the costs of the different secondary linings available and thus any figures quoted should only be taken as a guide.1. The cost of cast iron. Grey iron segments are generally of similar lengths for most diameters of lining. The cost of a master for an iron segment is of the order of £3000 to £5000. Small surface undulations or distortions may exist which are removed when the flanges are . both grey and spheroidal graphite. Secondary Lining Cast in-situ concrete Brick Infill panels Thin cement mortar linings Sprayed mortar Glass reinforced linings Other forms Percentage of total cost of Tunnel . Uncontrolled Copy. Two years ago the cost per tonne of spheroidal graphite iron was up to 5 0 per cent more than grey iron.Licensed copy from CIS: URS. decreased considerably over the last two years. Previously spheroidal graphite linings were not economical for diameters below 5 or 6 m as the saving in the material did not outweigh the additional cost of material.machined. that it will be feasible to omit the machining. 04/03/2015. however. 11. it is unlikely. Over the next few years it may well be more economifal t o cast all metal linings in spheroidal graphite rather than grey iron. One master is required for each type of segment and therefore for short lengths of tunnel in a special lining the costs of the lining will reflect this outlay in a similar way to the moulds for special concrete segments. The number of schemes lined in cast iron rings is relatively few and thus-pricingfor new schemes is difficult. at January 1976 prices is in the range £250 to £350 per tonne. The figures below are the range of percentages of the total cost of a tunnel attributable to the cost of the respective secondary linings. At present the foundry production lines are not working at a high capacity and the opportunities have been taken to improve casting methods. URS Infrastructure. except perhaps for the smaller segments in spheroidal graphite iron. Although the cost of this machining adds 5 per cent to 10 per cent on the cost of the lining. although of different flange depths. This differential has. inadequacy or silting up of the drainage system are often the initial causes of damage. however. In tunnels in stiff clays an invert should always be provided initially although it is often not necessary structurally for several years. are 100 years t o 150 years old with ever increasing maintenance requirements. crumbling of the brickwork. The bricks were often made from the excavated material from the tunnel or from local quarries which did not necessarily produce the best quality bricks for the purpose. bulges and cracks more often occur in the crown and haunches and t o a lesser extent in the walls. recaulking and maintenance t o the secondary or internal lining.2 Railway tunnels The majority of railway tunnels were constructed in brickwork or masonry and it is only in the last 30 t o 5 0 years that cast in-situ or precast concrete has been used. have in general required minimal maintenance. MAINTENANCE Licensed copy from CIS: URS. rebuilding 1 or 2 courses of brickwork. causing voids and exposing the timber to the atmosphere. For the old brick tunnels many of the records of the construction have not been preserved (if they existed) and only the original plans with typical cross-sections are available. The most general defects associated with brickwork railway tunnels are deterioration of the mortar. Where running water penetrates the lining of a tunnel in fine-grained material a void can quickly be formed behind the lining which is very likely to lead to instability. especially railway and sewer tunnels which were constructed in brickwork. The methods commonly used for the repair of tunnels are discussed briefly in the following sections. The reasons for The deterioration of the brickwork may be put down t o a number of factors including steam engine fumes. Cast in-situ concrete lined tunnels and precast concrete lined tunnels are considerably younger and to date have generally required little maintenance. it has sometimes rotted when leakage o f water has allowed it to dry out.12. Where falls of weak rock may occur protective canopies such as structural steel work or steel corrugated sheeting may be used with . sprayed mortar or concrete over mesh fixed to the brickwork. The methods commonly used for the repair of railway tunnels include repointing of the brickwork. 04/03/2015. In emergencies. When timber has been used for the temporary support behind the lining. Where pumping records are available a close check should be kept so that an inspection can be made if quantities of water o r sediment content change suddenly. 12.1 Road tunnels The majority o f road tunnels in the United Kingdom have been constructed in cast iron segmental linings. I n some instances the first two courses of brickwork have had to be replaced while in a few tunnels whole arches have been replaced where defective brickwork has been found behind. The spalling. All tunnels and shafts should be regularly inspected and records kept of any signs of deterioration. or more recently sprayed concrete with steel fibres (see Section 6. Where tunnels have n o structural invert. one or b o t h tracks may have t o be closed. Roman and lime mortars were the most commonly used and the latter has been the one most prone t o deterioration helped by sulphate attack.3) and rockbolting (see Section 6. cracks and bulges. bulges. cracks and leakage. URS Infrastructure. The only repairwork which has been necessary to date has been grouting. concrete segmental linings or cast in-situ concrete. many of which are 75 years to 1 0 0 years old. 12. The cast iron lined tunnels. Many tunnels in use today. Systematic grouting should be carried out when such problems threaten t o develop. The main difficulties of maintenance and repair of railway tunnels concern the limited clearance between the structure and loading gauge and the short periods available at night or at weekends when unrestricted work can be carried out.2). Uncontrolled Copy. running water and dampness. No sign of excessive erosion has yet been found but it could well be that without surface treatment their life will not be as long as for the brick linings. sprayed mortar linings.cement or chemical grouting to fill voids and seal the tunnel. The bolted type when first introduced was lined in brick but more recently cast insitu concrete has normally been used. Measures which have been used for the repair of brick-lined sewers include repointing of the brickwork. These internal linings should have low surface roughness and be thin in order t o minimise any reduction in the cross-sectional area of the tunnel. The brick lined tunnels are in many cases in need of repair and in London alone over 150 km will probably require to be replaced or relined in the next ten or twenty years. Sewer tunnels receive a considerable amount of wear in the invert. many of which have been in service for more than 100 years. cast in-situ concrete internal linings have only been common for the last 20 or 30 years. glass reinforced fibre linings and resin felt linings (see Appendix 2). . Several tunnels have been relined with reinforced concrete segments or with precast or cast in-situ invert arches. Licensed copy from CIS: URS. are lined in engineering brick with some sections in cast iron. 04/03/2015. either of the bolted or smooth bore type. where there is little superficial damage. The more recent sewer tunnels have been constructed with precast concrete linings. aluminium or other material which will protect the roof of the tunnel. In the past.3 Small diameter tunnels Small diameter tunnels include tunnels for sewers and for water. Brick internal linings have proved themselves over the last 100 years. Uncontrolled Copy. during short or long-term possessions of the tunnel. Where erosion has taken place or where the rock has deteriorated over half a century or more. Suitable materials include thin precast concrete segments. 12. URS Infrastructure. water tunnels were sometimes constructed through rock and left unlined. accounting for several thousand kilometres of tunnel in the United Kingdom. The older sewer tunnels. These internal structural linings are also suitable for damaged cast in-situ linings. remedial measures including new structural linings may be required. or constructing an internal lining inside the sewer which will take part or all of the structural load. and thus prevent the rock falling into the invert to obstruct the passage of water. These may be of cast in-situ concrete if the reduced cross-section area is acceptable or of a structural canopy of steel. Additional grouting to the back of the original lining may also be required to fill voids behind the lining and thus improve stability. It is recommended that any new specification should include the design criteria for the lining. a working party was formed in late 1975 and CIRIA report No 66 was published in the summer of 1977. . and cover only general items of concrete reinforcement and tolerances on dimensions. or 'similar approved'. 04/03/2015. The types of standard linings which are available fall mainly into two groups. In the next 10 t o 20 years casting techniques will be improved with the introduction of new methods. each manufacturer has a different lining which is normally protected by patent rights. The present method of specifying tunnels is by the internal diameter. especially for shield driven tunnels. During the next few years metrication will provide a convenient time to introduce a new range of diameters with convenient metric increments or t o reduce the number of diameters in the present range. It is generally agreed within the industry that there are considerable differences between the products of different manufacturers and it is therefore recommended that a performance specification for minimum requirements be drawn up t o provide adequate standards as a basis for control that the client or consulting engineer may exercise on design and quality of the lining supplied. The present ranges of standard concrete linings are now specified as metric conversions of the old imperial sizes. which is the diameter required by the user. (and will not correspond t o the internal diameter of the primary lining where a secondary lining is needed). Standardisation should also be extended into the special precast concrete and cast iron lining sectors to enable shields and segment moulds t o be used for several contracts. RECOMMENDATIONS 13. For the latter group. such as standardisation.1 Standardisation Licensed copy from CIS: URS. especially in the precast concrete standard ranges. cannot be carried out by sectors of the industry. but will require t h e cooperation of all parties. In several cases. and the need for standardisation will become more compelling. including local statutory and consulting engineers. handling and erection: this reinforcement may or may not be required for the permanent condition. such as the pressing of segments where the cost of a set of moulds is very large when compared with conventional moulds. The former group which account for the majority o f the standard market are all of similar form and are manufactured by most of the manufacturers.13.2 Specifications Many of the specifications drawn up for standard bolted reinforced concrete linings are based on those supplied by one of the manufacturers. URS Infrastructure. 13. From the construction point of view the external and the excavated diameters are the more important. It is generally agreed within the industry that standardisation of tunnel linings is long overdue and that there are too many diameters of tunnel linings available. in the majority of contracts the standard segments from the lowest tenderer will b e accepted with little questioning. Uncontrolled Copy. A major change. such as depth of tunnel. At present there are some half dozen manufacturers of precast concrete tunnel linings and in addition a number of contractors may elect t o cast segments at the site of the works. In a number of contracts it has been found that the flanges of the segments have been damaged during handling or the skin cracked due to excessive stress during the shoving of the shield. These are not fully comprehensive. The Construction Industry Research and Information Association (CIRIA) Committee on Underground Construction has included standardisation on its projected list of priorities. Although manufacturers will produce reinforcement drawings on request. The bolted form of lining is reinforced for the temporary condition of transporting. contractors and lining and shield manufactures. the linings have been specified in tender documents by particular trade name. the bolted concrete linings and the smooth bore linings. recognising the additional costs for high accuracy. The specification in these instances will normally be more comprehensive covering quality. in a similar manner to the development of the bentonite shield. the development costs will be very large. and require the manufacturer to produce calculations t o show the adequacy of the lining against such criteria.shield thrusts and other special conditions. The new linings which have been designed during the last decade have either been for specific schemes where the linings have evolved from previous schemes. 6 and 10. If this can take place simultaneously with the excavation considerable savings will accrue. In 1973. two-thirds of which was for precast concrete linings. or. Uncontrolled Copy. Great care would be needed in choosing such schemes. There has been a general trend in the last decade towards mechanical excavation. over 90 per cent of which was in precast linings. At present the thickness of sections of bolted segments and the extent and disposition of reinforcement vary between manufacturers. the tolerances should be related to construction requirements. This is equivalent to an average cost of £75 per metre and represents less than 10 per cent of the total tunnelling costs. . The present tunnel lining market. The design of a new lining may therefore require the development of a special tunnel shield or machine. Tunnelling costs are predominantly time dependent and therefore a substantial increase in the rates of progress with a new lining. Such a development was made with the Mini Tunnel but if the lining is to cater for the whole range of standard linings. The total length of tunnel constructed in that year was 120 km. 04/03/2015. In general. 13. which illustrates that for hand excavated tunnels the lining erection is the shortest operation in the cycle. The main exception has been the use of expanded linings. Again the quality of the concrete and the dimensional accuracy of casting segments vary between manufacturers and should be adequately covered by the specification.1 the cycle of excavation and erection of the lining has been discussed. the recent peak year of tunnelling demandthe total turnover of lining manufacturers was of the order of a m . in one or two instances. after standardisation of diameters. erection of the lining may become the longest operation in the cycle. as discussed in Section 3. The forms of linings and the materials which merit consideration are briefly given below:- . for standard production. With these mechanical methods of excavation. possibly subsequently repayable. For longer and larger diameter tunnels in stiff to firm clays and weak to moderately strong rock full face machines have been increasingly used. The specific schemes are usually large and thus the high development costs have easily been absorbed in the overall costs. and it has been shown that in general these are conservative methods which have been used for several decades. For special linings the design is carried out by the consulting engineer or promoter who will specify requirements for the lining. fluctuates considerably according to the state of the economy and is thus not the ideal place for a tunnel lining or shield manufacturer to put aside large capital sums on development. It is therefore recommended that consideration should be given to grants. URS Infrastructure. would soon recover the development costs. dimensions and even the manner of casting. 5 . to manufacturers of linings and shields or other organisations who wish to develop innovatory lining systems.2 and in Appendix 2. The development and marketing costs for new standard linings are high and it may be several years before the lining is used for a tunnel contract and several more before the lining is in full production. 4 . In Section 10. say 25 per cent.3 Development of linings The present methods of lining tunnels have been discussed in Chapters 3 . strength. and assessing their viability and long term profitability. Licensed copy from CIS: URS. For a new lining t o be viable it must offer advantages over the existing linings and therefore one important criterion will be the time and method for the erection. 4 Waterproofing Flexible caulking compounds have been discussed in Section 9. 4) An investigation of new materials such as glass reinforced plastic (GRP). The trials in the ideal conditions of the laboratory have often been successful. Present tunnelling in the United Kingdom is predominantly in soft ground and therefore the continuous extrusion of cast in-situ concrete behind a shield is unlikely t o be developed in the next few years. The caulking trials which have been made with a variety of flexible compounds in a number of tunnels. 8) Present research at BRE and TRRL in the methods and control of sprayed concrete will be of great importance in furthering its use taking account of controlled use overseas. Although the production of linings in these materials may not be economic in the foreseeable future design studies should continue. 1) The development of the use of expanded linings in strata other than stiff to firm clays and the method of sealing the joints. or concrete (GRC). have been o n a relatively small scale and often at the initiative of the manufacturer of the caulking compound. The monitoring o f . 6) There may be justification for carrying out further lining trials in a deep tunnel for which purpose commercially justified tunnels might be driven in advance of their need.the stresses and deformation associated with a complete ring of segments is important. Development in the United States is considerable in this field and should be monitored although n o economic lining has yet resulted. 7) There is still a great need for studying improved support methods for jointed rock formations in Britain and for improved means of assessing the tunnelling problems for economic investigations. Further rock bolting studies need t o be carried out t o improve design methods. Testing of individual segments has often been carried out and occasionally the loading of rings. When new linings are developed some form of testing of the lining is necessary as discussed in Chapter 7. Such work requires a substantial approach where full size or scale model rings can be assembled and loads applied to the periphery t o simulate the actual ground conditions including variation in the horizontal pressures. As the present cost of the material is high.4 with particular reference to expanded concrete linings. 13. erection and material components need to be studied. Testing of a spheroidal graphite lining was considered recently but the costs were found t o be prohibitive for an individual scheme. Most of the compounds tried to date have been materials . a completely new approach will be necessary rather than the development of existing forms in these new materials. 04/03/2015. wet and dirty. URS Infrastructure. Such an apparatus could be used for commercial testing and for research into ground lining interaction and lining behaviour. but have failed in the tunnel where conditions are often damp. Uncontrolled Copy. and research into. 5) The optimum size of segments for manufacture. The potential and cost of a laboratory testing rig with a capacity to simulate actual ground conditions at considerable depth needs t o be investigated.Licensed copy from CIS: URS. 2) Investigation o f the merits o f deformable precast linings which are more compressible circumferentially 3) Investigation of other forms of continuous erection of precast concrete or cast iron linings. or resinimpregnated concrete. and the improvement of the present methods of erection. if any. Future applications of these linings may be in water-bearing strata and thus it is essential that one or more satisfactory caulking compounds are found. New methods. Uncontrolled Copy. However. if the new materials are t o be considered for all forms of lining. If the circumferential flanges of the segments are not in direct contact the successful material must be capable of sealing gaps up to 25mm wide. which represent up to 20 per cent of the total length of tunnels constructed. Flexible materials are likely to be considerably more expensive and thus new quicker methods of application are required to offset these additional costs. trials will be required over relatively long lengths of tunnels. or painted compounds on. the main seal to prevent the ingress of water is the caulking of the joint at the inside of the tunnel. have not required caulking. New methods for concrete linings need to be investigated. Caulking of a tunnel lining is labour intensive with the material cost of cement based compounds relatively small. Licensed copy from CIS: URS. in the laboratory where a satisfactory material and method of application would be obtained in a simulated tunnel environment. made to very tight tolerances. on a long length of tunnel. need to be considered for sealing the water at the back of the joint or in the depth of the joint where any build up of pressure will compress the material in the joint into a wedged shaped profile. The present methods of waterproofing tunnels include sealing strips in. The introduction of new waterproofing techniques at the back of. where the work could be carried out without interference from other tunnelling operztions. In a tunnel the main purpose of the seal is to hold back the water pressure which tends to tear the jointing material away from its bond to the lining. secondly. . The meeting faces of the segments have direct contact and adjustments to the line and level of the rings are made with taper rings. and in particular the German practices. 04/03/2015. will require fundamental alterations to the design of the joint. water pressures. have been minimal. but these have not reached the production stage. in spheroidal graphite cast iron or concrete. Expanded concrete linings. Any sealing technique must be quick and 'miner proof. the joints which help to reduce the quantity of water entering through the joint. in particular by the manufacturers. and relatively high cost but achieving a notably high standard of finish with waterproofing by waterbars bonded into the segments. have been used mai'nly in firm to stiff clays which. Firstly. in addition to the present trials confined to a few rings. Wedge shaped grooves. For new compounds to be successfully introduced for the present forms of lining. Most of the present caulking grooves are parallel sided which depend on adhesion of the material to the sides. This principle of tapered rings has been used for a number of tunnels with cast iron linings designed in the United Kingdom for a home and foreign market. except for a relatively small proportion of the length. where the main movement has been in the longitudinal direction causing the compounds to compress or elongate. Such experiments could be carried out in two stages. Several new methods have been investigated during the last few years for waterproofing cast iron linings. URS Infrastructure. the thickness of which may vary from segment to segment.used for sealing joints in slabs. which have been specified for cast iron linings and some special linings could also be considered although there may be greater difficulty in using the caulking tools. or in the joint. The cost of caulking represents approximately 10 per cent of the tunnelling cost per metre and thus represents several million pounds worth of work in a year. Some consideration should be given to the German practice where the preference is to the use of linings. different stresses will occur than if the flanges were in contact over their length. in most ground conditions. Theoretical analyses based on tunnel data and laboratory testing will help t o obtain a better understanding of the changes in stress associated with tunnelling . which will cover most ground conditions. especially for the larger schemes. These tests will provide not only a means of understanding scale effects but will also provide an essential link between model and prototype behaviour. monitoring and research The major part o f the effort and resources for research and instrumentation in tunnelling is now channelled through Department of the Environment (DOE) Research Organisations. with the use o f centrifugal model testing. 04/03/2015. at a particular joint.13. however. The method and accuracy of the erection of the lining has a considerable effect on these stresses. TRRL and BRE. . In Chapter 7 the various forms of instrumentation and monitoring of tunnel linings and ground movements have been discussed t o illustrate the small amount of information which is available generally. Uncontrolled Copy. Some instrumentation will. The parallel work of laboratory experiments and the analysis of tunnel behaviour needs to continue. except perhaps for tunnels in London Clay. Instrumentation o f lining stresses has shown that the stress in the lining may approach the overburden pressure as discussed in Section 7. A programme needs t o be drawn up for research during the next 5 to 10 years. In the longterm TRRL will take over responsibility for all DOE research in tunnels. Where possible such monitoring should include the measurements of porewater pressure in the ground. the load is taken on the internal edge of the flange due t o "bird's-mouthing" of the flanges. More data is required on hoop loadings in tunnel linings at selected locations and on the deformation of linings as loads build up. Studies of the effect of these conditions on the stresses in a lining would be beneficial to establish the additional factor of safety required to allow for building inaccuracies. For example if a flanged lining is built such that.5 instrumentation. still be financed through contracts. Further information is required on surface and subsurface ground movements associated with tunnels of different diameters at different depths and varying cover to diameter ratios. Licensed copy from CIS: URS. URS Infrastructure.5. URS Infrastructure.ACKNOWLEDGEMENTS The work described in this Report was carried out for the Tunnels Division of the Structures Department of TRRL. . The authors are grateful to TRRL for the opportunity to carry out this survey and for the assistance given by members of the Tunnels Division. Licensed copy from CIS: URS. In particular the authors wish t o thank Mr M P O'Reilly. and Dr S D Priest for his valuable assistance during the final stage of the preparation. Head of the Division. Dr M Dumbleton. advice and encouragement. 04/03/2015. Uncontrolled Copy. Dr J A Hudson and Dr R G Tyler who have during the course of the survey given valuable assistance. Mr B Boden. URS Infrastructure. Uncontrolled Copy. 04/03/2015. Licensed copy from CIS: URS. Visits and correspondence were held with the following organisations. Local and Statutory Authorities Corporation of Blackpool City of Birmingham City and County of Bristol British Railways Central Electricity Generating Board County Borough of Derby Corporation of Edinburgh Corporation of Glasgow Greater London Council City of Manchester Milton Keynes Development Corporation Northumbrian Water Authority North of Scotland Electricity Board Sandwell Metropolitan Borough Southend Borough Council City of Stoke Thames Water Authority Consulting Engineers Babtie Shaw and Morton D Balfour and Sons Binnie and Partners C H Dobbie and Partners Oscar Faber and Partners Sir Alexander Gibb and Partners Sir William Halcrow and Partners Charles Haswell and Partners Howard Humphreys and Sons G Maunsell and Partners L G Mouchel and Partners Mott Hay and Anderson J D and D M Watson Sir Owen Williams and Partners Civil Engineering Contractors Amey Roadstone Construction Ltd Balfour Beatty and Co Ltd Bovis Civil Engineering Ltd Charles Brand and Son Ltd Cementation Mining and Civil Engineering Co Ltd Leonard Fairclough (Buchan Division) Ltd Foraky Ltd Kinnear Moodie (1 973) Ltd Sir Robert McAlpine and Sons Ltd Miller Bros and Buckley Construction Ltd Edmund Nuttall Ltd Mini Tunnel International Rees Hough Ltd Taylor Woodrow Construction Ltd Thyssen (GB) Ltd A Waddington and Son Ltd .14. The Authors and the Transport and Road Research Laboratory are very grateful for the cooperation and helpful assistance given by all consulted. APPENDIX 1 List of organisations consulted Discussions were held with many organisations concerned with tunnelling. On account of the large number of organisations concerned with tunnelling only a relatively small but representative cross-section could be contacted. a large number of which were visited on one or more occasions during the course of the survey. Colleges and Associations Building Research Establishment Concrete Pipe Association Pipe Jacking Association Sunderland Polytechnic University of Cambridge University of Durham University of Glasgow University of Newcastle-upon-tyne .Primary Lining Manufacturers Anglian Building Products Ltd Armco Ltd C V Buchan (Concrete) Ltd Charcon Tunnels Ltd Commercial Hydraulics Co Ltd Costain Concrete Co Ltd Croxden Gravel Ltd Empire Stone Co Ltd Head Wrightson and Co Ltd Redpath Dorman Long Ltd Scottish Construction Ltd Silverton Associates (Bemold System) Spun Concrete Ltd Stanton and Staveley Ltd Shield Manufacturers Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy. Universities. 04/03/2015. Cementation Ground Engineering Centreline Ltd Stabilator Ltd UK Pressure Whitley Moran Ltd Caulking Chemical Building Products Ltd Colebrand Ltd Deepseal Ltd Expandite Ltd Servicised Ltd Vandex Ltd Secondary Lining Manufacturers Charcon Composites Mortabond Ltd Redland Pipes Ltd Grouts and Admixture Specialists Colcrete Ltd Pozament Ltd Research Establishments. R L Priestley Ltd Stelrno Ltd Other Specialist Contractors Sprayed and Mortar Linings Caledonian Mining Co. I t was not possible t o prepare statistics for the years prior t o 1970 as records were not available from all manufacturers. and therefore the main effects of financial restraints do not normally occur for 1 to 2 years. cable and transport tunnels. but this will not affect the total of all tunnels b y more than 1 or 2 per cent. 1970-1 976 Licensed copy from CIS: URS. based o n the replies t o a questionnaire sent to each country. 15 t o 30 years.2 Total length of tunnels constructed: Fig. in June 1970. which it was estimated would give a figure close t o the actual length of tunnels and shafts constructed with these linings. 15. and the long term. During this survey it has been possible. When the results were presented it was stressed that there were important gaps in the information received. The estimated length may therefore be slightly o n the low side. The information obtained from the manufacturers of concrete and cast iron linings was the total number o f rings delivered t o all sites of each diameter in each of the calendar years 1970 t o 1976. ~ out an assessment of the likely extent of future tunnelling and In 1972 t o 1973 BRE and T R R L ' ~carried the types of ground involved for the immediate term. the actual length of tunnel constructed in each calendar year was obtained from the consulting engineer or the contractor and for rock tunnels which were left unlined or lined in cast in-situ concrete the lengths excavated in each calendar year were obtained from the user. the annual length of tunnels constructed has been virtually constant. The length of .15. For this latter category of lining. which may account for a further 5 per cent to 10 per cent. 04/03/2015. with the cooperation of the tunnel lining manufacturers. however. Where segments were cast on site. however. the medium term. 0 t o 5 years. cast in-situ concrete and cast iron lined tunnels are usually large capital projects.1. details of tunnels had t o be obtained from many sources all over the country. which are predominantly for the sewer market with short lengths for water. The total lengths of tunnels and shafts d o not. The concrete bolted and smooth bore linings. sustained a severe set-back in the early part of 1 9 7 4 while for the other three forms of linings this did not occur until the latter part of 1974.1. nor for mining shafts and roadways. divided into the several forms of lining. consulting engineer or the contractor. O n most sites the working area is relatively small and there is only storage capacity for a few weeks supply of segments. USA. include pipe jacking and timber heading. concerning the demand for tunnels in the period 1960 t o 1969 and the future estimates for the period 1970 to 1979. less than 10 per cent of all tunnels. URS Infrastructure. to establish the approximate lengths and volumes o f tunnels and shafts constructed for civil engineering purposes during each of t h e calendar years for the period 1970 t o 1976. statistics were drawn up. Uncontrolled Copy.1 Tunnel lining demand. and therefore the data should be taken only as a n indication o f the magnitude of the demand. accounting for a relatively small number of contracts. for each of the calendar years 1970 to 1976.which are greatly in excess of civil engineering tunnelling. spread over several years. The figure shows a peak in 1973 with a sharp reduction in 1974. 27 gives the total annual length of tunnels and shafts constructed. Since this drop in 1974. 15. For the OECD Advisory conference on tunnelling held in Washington.1 Collection of data: At any one time a hundred or more tunnels are under construction throughout the country. 5 to 15 years. For the UK such estimates are somewhat simplified by the fact that at least 9 0 per cent of all tunnels use preformed linings. due partly to the reorganisation of the local authorities and partly to the economic situation. The expanded concrete. APPENDIX 2 Primary and secondary linings - general 15. 6 4.0 10.3 2.1 2.5 5. 15.6 3. 31 shows the range of the cumulative percentages of total lengths of tunnels lined with precast concrete segments for the period 1970 to 1976 plotted against internal diameter.4 3.1 m to 2. The weighted overall average diameter is likewise relatively small. which are included in the bolted and smoothbore linings.6 2. The weighted overall average is based on the total length and volume of all linings. at a nadir in 1971.1 5.3 Total excavated volume of tunnels constructed: Fig. Licensed copy from CIS: URS.1.4 2.6 2. are relatively small.1.9 2.6 4.2 2.5 2.9 2. however. In 1975 this percentage rose to 90 per cent as relatively little tunnelling was carried out with the other forms of lining. The fluctuating figures for the cast in-situ concrete lined and cast iron lined tunnels make little difference to the overall average on account of their relatively small percentage of the length of tunnel. with the exception of 1971 which was influenced by the Mersey Kingsway Tunnel. The lengths of these road tunnels in concrete lining.4 Average external diameters of tunnels: Table 17 shows the average external diameters of each type of lining based on the annual lengths and volumes.8 2. The surprising conclusion from this table is the very low average diameter for the precast concrete bolted and smooth bore linings which give average external diameters of 2.8 2. The percentage volumes for each form of lining are given in Fig. The weighted diameter for 1971 is affected by the Mersey Kingsway Tunnel. which is omitted from the figure in brackets at the bottom of the column.5 3. Uncontrolled Copy. the Mersey Kingsway 2B Tunnel and the Dartford Duplication Tunnel.3 3.5 2.5 7.O 2.0 5.4 2.3 m. The bolted and smooth bore linings account in general for between 45 per cent and 60 per cent of the total volume. Many of these recent contracts commenced in 1971 and 1972 with tunnelling completed by early 1974 and thus the effects have been felt earlier than might be expected with only a few contracts let to replace them.6 11.0 8. 27) for the length of tunnel.4 rn to 2.4 3. This again shows the small diameter of tunnels.6 3. .4 3. The annual variation in the volume of excavation is similar to that (see Fig.7 11. URS Infrastructure.6 m or equivalent average internal diameters of only 2.6 3 .7 11. 50 per cent of whlch are below approximately 2 m and 90 per cent below approximately 3 m.5 4.1 3.8 2.6 (3. Fig. The percentages of volume for the other three forms of lining fluctuate more dramatically than the percentages of length.0 5.1 Fig.5 - - 5.6 4.tunnels constructed with these latter forms of linings was.2) 2. while the excavated volumes are comparatively large. TABLE 17 Average external diameters Year Concrete bolted and smoothbore (A) Expanded concrete (B) Weighted average of (A) and (B) Cast in-situ lined or unlined Precast concrete road tunnels Cast iron Weighted overall average 1970 1971 1972 1973 1974 1975 1976 2.4 11.8 - 2. 15. 30. An additional subdivision has been included for road tunnels lined with precast concrete lining. 29 gives the annual volume of excavation for tunnels and shafts constructed with each form of lining during each of the calendar years 1970-76.2 11. 28 gives the percentages of the total length of tunnel constructed in each form of lining and shows that the bolted and smooth bore linings account generally for between 70 per cent and 80 per cent of the total length. 04/03/2015.0 4.0 2. The expanded concrete.3 1.1 70.2 2. The total length of tunnels constructed in 1975 and 1976 was very similar to that in 1974 and thus any estimates for the 1976 t o 1980 period based on the 1970 to 1974 period must be considered in the light of the present financial conditions.6 . Allowing an overall annual increase over the period of 3 per cent to 7 per cent the estimated length of tunnels constructed in the period would be 475 km t o 575 km.0 0.4 8. cast in-situ concrete or unlined tunnels and cast iron lined tunnels .3 12.7 20.1 74. water.8 4.6 4.5 Tunnelling in 1976-1980: Licensed copy from CIS: URS.4 8. is increasing and if the financial climate improves as it appears likely to.3 2.8 13.5 67. especially for expanded concrete and cast iron lined tunnels which accounted for 67 km and 12 km respectively of tunnel during the 1970 to 1974 period.2 29. URS Infrastructure. TABLE 18 Tunnel usage .8 70. For cast in-situ lined or unlined tunnels.4 29.however . Tables 18 and 19 give the percentage of the total length and volume of tunnels for each tunnel usage for each of the years 1970 to 1976 and the average for the period.6 1. water and cable tunnel percentages. In general.percentage of total length TUNNEL USAGE 1970 1971 1972 1973 1974 1975 1976 Sewers Cable Water Rail and Associated tunnels Road %other than sewers % road and rail 67. two-thirds of the length of tunnels is for the sewer market and between 40 per cent and 5 0 per cent of the volume.8 23. which accounted for 112 km in the 1970 to 1974 period.0 5.7 25.0 4. Any prediction for the 1976 to 1980 period based on schemes under consideration is outside the scope of this survey. and the Dinorwic tunnels both of which commenced in 1975.4 5. There are however considerable fluctuations for the other usages of tunnels from year to year.7 5.9 32.3 15.7 0. pedestrian and railway and other associated tunnels.15. which accounted for 3 3 km for the last five years. cast in-situ concrete and cast iron linings are easily subdivided on account of the small number of schemes. 04/03/2015.1 15. of 32 km. The bolted and smooth bore concrete linings have been subdivided where possible but some small errors may exist between the sewer.7 87.0 1.9 0. but any large injection or reduction of finance could alter these figures considerably. Uncontrolled Copy. For the remaining 25 per cent to 30 per cent.4 3.2 13.2 4.4 - 1. Unless several more large schemes are started in the latter part of the period there is unlikely to be a continued sustained increase in the overall length of tunnels using these three forms of lining.the expanded concrete.7 0.7 3. The remaining percentage includes cable.7 1. this demand will continue t o increase during the period 1976 to 1980. which account for over 70 per cent of the market.there must be some reservations.1.2 14.1. There are at present fewer schemes under construction or consideration than during the 1970 to 1974 period.2 27. the proportion for sewers fluctuating from year t o year between 85 per cent and 95 per cent of the total lengths of tunnels.6 3.0 0. The demand for bolted and smooth bore linings.6 Tunnel usage: The concrete bolted and smooth bore tunnel linings are predominantly for the sewer market. there will be a large increase mainly due to the Tyne-Tees aqueduct. service.3 80.6 32. 15.0 2.6 0.8 19. 4 1. For sewer or water tunnels the secondary lining provides a smooth finish to the tunnel.5 1.9 52.5 18. be easy to clean. 04/03/2015. linings linings 44 45 46 47 48 49 50 51 52 53 - * * * .2 71. Secondary linings are briefly considered in this Report in order that cost comparisons can be made between the different forms of primary linings. the secondary linings used for bored road tunnels recently constructed are briefly listed in Table 21. For road tunnels the lining must. offering a high resistance to corrosion.5 48.5 15.2 28.1 4. It is beyond the scope of this Report to give details of the many materials and methods of application available.5 15. For reference.1 36.6 53.8 35.1 32. the secondary lining serves as a waterproofing (or shielding) membrane.5 4.1 - 58.6 9. passenger concourses and pedestrian subways. URS Infrastructure. as partial insulation against noise and as an aesthetic finish.1 47.5 28.6 71.1 3.9 0.6 24.3 31.2 Secondary linings In Table 2. Secondary linings marked (2) require a smooth bore finish to the primary lining of in-situ concrete or infill panels.4 14. Tunnel usage .7 42.1 0.9 25.1 1.h * * * *(2) * * WATER TUNNELS Bolted Smooth bore linings linings * * * * * * * * * * * * 1. For road tunnels.5 5 -0 5. TABLE 20 Secondary linings for sewer and water tunnels Secondary lining Brick (CR) Cast in-situ concrete Infill panels Thin cement mortar Sprayed mortar Steel Glass fibre reinforced cement (CR) Glass fibre reinforced plastic (CR) Resin felt (CR) Epoxy tar (CR) Bitumen (CR) NOTES: SEWER TUNNELS Bolted Smooth bore Plate no.7 32. .6 9.0 4.4 13. the use of bolted and smooth bore linings is examined in conjunction with the need for a secondary lining. only some of which require secondary linings. in the main Report.7 0.5 47.4 21.TABLE 19 Licensed copy from CIS: URS.5 51.5 18. prevents erosion and may act as a corrosion barrier.2 52. Secondary linings marked (CR) are resistant to many acids and alkalis.6 29.8 15.1 18.1 2. Uncontrolled Copy.0 14. however. in addition. The different forms of secondary lirung are given in Table 20 and briefly discussed in the following sub-sections. have a good reflective surface and present an acceptable fire rating.9 18.percentage of total volume TUNNEL USAGE 1970 1971 1972 1973 1974 1975 1976 Sewers Cable Water Rail and Associated tunnels Road % other than sewers % road and rail 46. 2. be durable.6 41. 1 Brick lining: As discussed in Section 3. Fort Regent Jersey 1968-70 Cast in-situ concrete No secondary lining. Uncontrolled Copy.TABLE 21 Secondary linings for driven road tunnels Date Primary lining Secondary lining to walls Dartford 1956-63 Cast iron Concrete t o ceiling level with 38 mm square opaque glass mosaic. clay or shale.Bricks and blocks o f fired brickearth. low absorption. being one of the best available wearing surfaces for sewers. A brickwork lining is smooth and durable. Similarly the use of brickwork as an internal secondary lining to bolted cast iron or concrete linings has also reduced. URS Infrastructure. For cast iron sections similar sheets supported from the cast iron lining. For small diameter tunnels radiused bricks should be used. Birmingham Gt. Tunnel 15.2. Clyde 1957-64 Cast iron PVC sheeting on extruded aluminium frame. 98 . Crindau Newport 1963-67 Cast in-situ concrete Concrete dado 1.5 m high with PVC sheeting supported on extruded aluminium alloy bars.2 the use of brick as a primary lining has reduced considerably during the last t w o decades. without frogs. coated with epoxy paint. coated with epoxy paint. mainly because of the increased cost of materials and labour when compared with the cost of other forms of secondary lining. For cast iron sections similar steel sheets supported from the cast iron lining. Light steel vitreous enamelled panels with double coated light textured finish. Licensed copy from CIS: URS. 04/03/2015. Blackwall Duplication 1960-67 Cast iron Aluminium sheeting with PVC coating. which in turn has caused a scarcity of experienced skilled labour. Heathrow Cargo Tunnel London 1966-68 Precast concrete PVC sheeting on extruded aluminium alloy bars. The bricks. Gibraltar Hill Monmouth 1965-67 Cast in-situ concrete PVC sheeting. the internal ring should be built in the best-quality. Charles Street 1968-70 Cast in-situ concrete A thin trowelled finish. For brick linings in sewers. Dartford Duplication 1972-78 Precast concrete or cast iron Steel sheets cast onto precast concrete primary lining. As an alternative t o a complete brick lining an invert of brick with a cast in-situ concrete lining above may be used.3. where scour o r high fluid velocities are expected. Mersey Kingsway Tunnels 1967-74 Precast concrete or cast iron Steel sheets cast onto precast concrete primary lining. Brick linings or inverts in brick are still used in certain conditions where the effluent is likely t o be aggressive. Tyne 1961-67 Cast iron Concrete t o axis. engineering bricks available. or for durability (see Plate 44). should be in accordance with British Standard BS 3921 . Load tests have been carried out on the bond between the segments and the panels. The concrete may be 100 mm to 150 mm thick inside the flanges of the primary lining t o allow for the tolerances in the construction of the tunnel. The internal brick skin will either be built up clear of the lining and the void backfilled with concrete as the work progresses or infill panels will be fitted to the segments to give a smoothbore finish and the internal skin erected close t o this surface with a rubber latex base between. The invert level can easily be adjusted to correct the inaccuracies of the construction of the tunnel to give a smooth finish. Back grouting may also be necessary. 15.2. Timber laggings are the common method of shuttering for small diameter tunnels although segmental steel shutters are occasionally used. Investigations have recently been carried out by the Northumbrian Water Authority for the new Tyneside sewerage scheme to obtain a ring with an adequate bond between the bricks. up to five lengths are cast on a one day shift. these latter require tight concrete control and supervision a t the surface and in the tunnel where vibration of the concrete will be necessary.2 Cast in-situ concrete linings: Cast in-situ concrete is at present the standard internal lining for sewers with primary bolted cast iron and concrete linings and has taken over almost completely from the brick internal lining. is the mortar between the bricks which will not take tension. the void between this surface and the brickwork being filled with mortar. URS Infrastructure. however. To avoid the possible debonding of the units in the crown. of debonding following the commissioning of a tunnel. set into a recess cast into the secondary concrete lining.2.3 lnfill panels: The standard precast concrete bolted linings manufactured all differ slightly in their cross-section and thus different infill panels are required for each lining to give a smooth bore finish. The characteristic strength specified is normally in the 2 0 to 28 MN/m2 although higher grades have been used. Invert finishes may be of lugher grade granolithic concrete or of brickwork. 15.3) may be used to give a smooth internal bore to the primary lining. The panels are bonded with a cement/pulverised fuel ash mortar mix. The weakest link in the ring. These panels are used mainly for water tunnels or stormwater sewers and it is not recommended that they be used for effluent sewers unless special primary lining segments are cast with larger cover to the reinforcement than standard segments. If adequate precautions are taken in sealing the shutter joints to avoid loss of grout with steel shutters. There have been no cases. the finish may be better than that obtained with timber laggings. The primary lining will normally be of bolted cast iron or concrete segments. Uncontrolled Copy. With bolted primary linings the brickwork may be built up clear of the internal diameter of the primary lining and the void behind filled with concrete as the work progresses. For larger diameter tunnels travelling shutters may be used.Licensed copy from CIS: URS. however. Alternatively precast infill panels (see Section 15. This type of brickwork is. This lining has been designed for tunnels of 2 m diameter and over. however. Grouting behind the secondary lining t o fill any voids should b e carried out at a later date. These cast in-situ linings have only been used for the last 2 0 t o 3 0 years and no assessment has been made of their useful life though repair of these linings will be more difficult than for brick linings (see Plate 45). This form of internal lining will be used for a number of contracts during the next few years. depending on the size of tunnel. If a two shift system is worked the shutters may be removed on the night shift or early on the next day shift. expensive and requires highly skilled bricklayers. These infill panels consist of accurately shaped precast concrete units designed to fit into the recesses between the flanges and the ribs of the segments with a nominal 6 mm clearance. The 'Bucfil' panels manufactured by C V Buchan (Concrete) Ltd are made of lightweight aggregate. The shutters are normally 3 m to 5 m long and. Although it is normal t o cast the secondary lining concentric with the primary lining some local authorities prefer to have a larger thickness in the invert t o give longer protection against scour. sand. For large diameter sewers the top arch will require supporting on timber laggings until the arch is complete. The latex has been designed to set under damp conditions. . pulverised fuel ash and ordinary Portland or Sulphate resisting cement.2. good control of the workmanship is essential. using an epoxy resin joiniing material. Tests were carried out in the laboratory with an epoxy resin joint between engineering bricks which showed that the jointing material was stronger than the bricks. 04/03/2015. The installation is quick and normally cheaper than a cast in-situ lining (see Plate 46). The gradings of the cement and sand and the quantity of water must be kept between very fine limits to give a satisfactory application in the tunnel. in the Hazen-Williams formula. tunnels include the 27 km Thames to Lee Valley ~ u n n e in first stage. 15. 15. Their use has been mainly for lining new cast iron or steel pipes and for relining old pipes. The coefficient of friction of the finished surface is equivalent to a c value. Mesh reinforcement was used and the suiface was screeded and trowelled to give a smooth finish.4. which is at present applicable to tunnels up t o 4 rn internal diameter. of 120 to 140. Admixtures may be added. Sprayed mortar was also used in the 1960's as a secondary lining for the top 240' of a sewer tunnel after casting a n in-situ concrete lining in the invert. The lining can be applied at 100 to 500 m per week. involves the application of a thin mortar lining. form of lining is now mainly lining was used for the 1. The lining may also be required to resist the external pressures when the tunnel is empty.5 Sprayed mortar or gunite linings: The principles of sprayed linings are discussed in Sections 6. The materials. The mix varies between 1 : 1 or 1 :2 cement to sand with a water:cement ratio b e h e e n 0.6 Steel linings: Steel internal linings have generally been used for water and road tunnels. Before applying the materials the tunnel must be cleaned of all grease and oil. On the ground surface where the materials are mixed good quality control is essential. Panels in ordinary Portland Cement or Sulphate resisting cement with normal aggregate are available if required t o fit both the Buchan and Charcon bolted segments.2. up to 19 mm thick in one or two layers. URS Infrastructure.5 mm thick ' . using a centrifugal pump rotating at up to 1500 revolutions per minute. 15.3 and 18. the mortar lining is cured in a (dampatmosphere with a small depth of water in the invert. These 1 the ~ ~ late 1950's and the 19 km Southern Tunnel.8 km steel section of the Cross Hands ~ ~ u e d u c t ~This used as an internal lining in conjunction with precast concrete lined tunnels for filtered water tunnels where it is essential t o prevent the ingress of ground water (see Plate 47). Although the mortar can be applied over some small damp areas. Where two coats are applied the first coat is not normally floated. Sprayed mortar has normally been used for relining old tunnels. The lining bonds well t o the primary concrete or steel lining but as the lining acts as a continuous ring in compression very small unbonded areas will not affect the lining strength. The surface is given a smooth finish by trowels rotating at speeds of 5 to 25 revolutions per minute a t the back of the machine.4 Thin cement mortar linings: Thin cement mortar linings applied by centrifugal force from electrically driven equipment have been used in the United Kingdom since the mid-1 950's.3. In new tunnels sprayed mortar was used for a number of sewers in the 1950's and 1960's where the primary lining was of bolted concrete segments (see Plate 48). are supplied to the pump through a screw worm feed.2. which compares well with shuttered concrete. although there are a small number of instances where it has been used as a secondary lining for new tunnels. particularly where the cover t o the tunnel is low. any larger areas or running water must be temporarily dried or sealed. A 9. which has recently been completed. Its use for repairs t o old tunnels is discussed in Chapter 12. The process. Uncontrolled Copy. For water tunnels the steel linings are used for high pressure shafts and tunnels to resist the bursting pressures of the water carried in the tunnel. The process has been used for a number of water tunnels constructed for the Thames Water Authority (formerly the Metropolitan Water Board). In addition the internal steel lining gives a smooth lowfriction surface and acts as a waterproofing membrane to prevent the ingress of ground water into the tunnel and . The pans to the segments were first filled with cast in-situ concrete before applying a sprayed mortar finish 25 to 5 0 mm thick. which have deteriorated during the years.2. which are normally mixed above ground t o give good quality control and to avoid congestion in the tunnel. After application. 04/03/2015.Licensed copy from CIS: URS.35 and 0. In both cases a thickness of 13 mm was applied. which has been used to reline a long eggshaped sewer in Jersey. The segments are erected and the void between the old lining grouted. For the Cross Hands ~ u n n e l ~(see lining was used at the two ends for a total length of 1. 04/03/2015. Sewer entries are formed during the erection and troughs in the level of the primary lining invert removed to avoid ponding. The void behind the steel linings is backfilled with concrete and back grouted (see Plate 49). called the Mortabond System. GRP has normally been used for relining old tunnels but may be used for secondary linings in new tunnels. A fibre reinforced concrete lining is also manufactured by K. fibre reinforced cement (GRC) and glass reinforced plastic (GRP).8 km where the cover to the tunnel was not sufficient to take the internal pressures.this is normally rapid hardening Portland Cement.7 Glass reinforced linings: There are two forms of glass reinforced linings which have been used in tunnel linings. a thickness of 16 mm was used but subsequently the thickness has been reduced to 10 mm.5 m long.1. except for the invert section which has an antiskid surface. The surface is smooth with a low coefficient of friction compared with concrete. For new tunnels the lining is fitted to a smooth bore lining or a bolted lining with cast in-situ concrete or infill panels. although it is essential to examine likely effluents to confirm suitability. and has abrasion resisting characteristics comparable with other secondary sewer liners (see Plate 51). for a new tunnel in London. The. 15. URS Infrastructure. with 100 mm smaller internal diameter than the tunnel. In the Foyers pumped storage scheme steel linings were used for the high pressure tunnels and shafts. A steel internal lining was used for the experimental length for the Thames to Lee water tunnel with a cement mortar internal face. The invert segment is normally 1. The thickness of the steel pipes varied from 18 mrn to 35 mm and the grout holes were predrilled.2. The GRC panels are lapped and located using wedges before fixing with screws or nailed with an impact gun and grouted. which consists of panels 12 to 18 mm thick. The material can thus be designed to ensure resistance to most of the acids and alkalis likely t o be encountered. In the first application. This lining.0 m long and the remaining segments 0.seepage out of the tunnel. but for more aggressive effluents the higher duty resins should be used. Glass reinforced plastic is manufactured from E-fibre glass reinforcements and resin by Redland Pipes Ltd.10~duty linings will be unaffected by the normal effluents permitted. The joints between the lining are ogee joints. It is light and of thicknesses varying from 5 to 19 mm depending on the diameter. Fibre reinforced cement panels manufactured by Charcon Composites Ltd using Cem-Fil fibres have been used in a number of tunnels as a secondary lining or for relining old tunnels or shafts.The material is light and can be manufactured to any shape or size to suit the actual tunnel and the ease of access into the tunnel. the site welding must be inspected and tested. GRP. All longitudinal welded joints and 10 per cent of the circumferential joints were x-rayed. The properties can be varied by altering the type of cement used . Licensed copy from CIS: URS. is moulded to the shape of the tunnel by a moulding process. a patent for which has been applied for. where progress of 10 m per eight hour shift has been regularly attained.1 9 5 0 ' s ~subsequent ~ water O Section 18. Following investigations carried out in the m i d .3) a steel tunnels in the London area have not been lined in steel. In general it has a good resistance to acids and alkalis. Uncontrolled Copy. It has a high impact strength and a low absorption and permeability. To ensure complete watertightness.can also be used for lining a new tunnel.W. A steel fabric reinforcement can be positioned behind the lining if necessary and entries can easily be cut into the sheeting. The type of resin can be altered to suit the conditions likely in the tunnel. The lining is usually fabricated in lengths of pipe and the individual lengths joined by site welding in position. to help maintenance staff during their routine inspections (see Plate 50). The lining. is normally supplied in pipes up to 3 m in length . Any type of surface can easily be provided.-Revai Chemicals Ltd. The process is similar for relining old sewers. During construction the surface material needs to be protected t o avoid damage. is prepared in the factory in tube form with a skin of polythene. The resin is cured by introducing steam into the outside of the tube (see Plate 52). sometimes with a . The one main exception has been the spheroidal graphite linings. however. although they may be used for several schemes. Resin felt: A new form of lining developed by Nuttall Insituform Ltd has been introduced in the last few years for relining old sewers. 04/03/2015. and thus cast iron is often preferred for waterproofing or other reasons. The concrete linings often consist of wider rings. The lining. Uncontrolled Copy. Openings can be cut into the material during curing. the lining methods used have been the conventional methods used in this country. is increasing faster than concrete and thus concrete linings are likely to be used more in the future. Epoxy tar: A new secondary lining has been developed by Spun Concrete Ltd consisting of fibre glass tissue sandwiched between two layers of epoxy tar. It is not comprehensive but shows. which allows storm water to pass through the central section during installation.8 Other forms of secondary linings: Licensed copy from CIS: URS. URS Infrastructure.which have been designed for schemes in North and South America in a form of cast iron little used in the United Kingdom for tunnel linings. The joints are normally of the spigot and socket type.3. In the United Kingdom tunnelling is predominantly in soft ground and weak to moderately strong rock and it is in these fields that our tunnelling methods have improved in the last two decades. 1. such as the bolted and smooth bore linings available in the United Kingdom. with only one or two exceptions. although if adequate precautions are not taken. where we may learn from their techniques especially from the larger diameter.1 Concrete linings: In many European countries the difference in the cost of cast iron lined and concrete lined tunnels is considerably smaller than in the United Kingdom. The lining has been used to date in only one tunnel where the invert segments were protected with rubber conveyor belt material. and thus most concrete linings are specially designed. to some extent. on the other hand. In several instances rings of four segments. There are generally n o standard concrete linings. 15.2. manufactured by Head Wrightson. The tube is inflated to take up the internal profile of the tunnel with the aid of a double skinned inflatable tube. Lengths of the lining are transported t o the site in a refrigerated vehicle t o delay setting. Site application of the material is required at the joints between segments and at position of grout holes and where the coating has been damaged (see Plate 53).0 m width has been used for many tunnels of medium and large diameter and generally are of fewer segments. which consists of polyester felt.and inserted in the tunnel. The lining material is introduced into the tunnel by conveyor and winched t o the location. rock tunnelling predominates with only a small proportion in soft ground. impregnated with polyester resin. The cost of cast iron and steel. high capital cost. which is 0. often only 10 to 15 per cent. some folds may occur at bends. but t o date it has not been used as a secondary lining for a new sewer. is applied by trowel to the internal face of the concrete segments at the factory. u p t o 19 mm thick. and the void between the primary lining and the new lining filled with PFA/Cement grout.3 Developments overseas This section covers briefly some of the foreign developments in tunnel linings which may be instructive to those familiar with British practice. The material has a high resistance t o abrasion and t o chemical attack. schemes. with a low friction resistance. to the correct circumference to suit the profile of the tunnel. The British manufacturers and contractors are moving into the foreign field although.5 mm thick. 15. 15. The surface is smooth. For many foreign countries. The material is tough and abrasion resistant and is chemically inert to virtually all likely trade effluents. The material. 32).2 Cast iron linings: Several of the cast iron linings designed in Europe in the last decade have differed considerably from the conventiona1.Licensed copy from CIS: URS. The designs in some instances have incorporated two forms of structural lining with a waterproofing membrane between the two (in the Alpine tunnels also to protect against icing). have been used the bolted linings have normally been solid smooth bore segments with recesses for the bolts. 33). key segment. As discussed in Chapter 9 grooves are machined into these faces and neoprene seals inserted which protrude about 2 mm which are compressed when the bolts are tightened thus forming a seal. Articulated joints.0 m to 1. At Hamburg the circumferential joirit was perpendicular to the centreline of the tunnel while at Berlin and Munich spiral linings with hexagonal segments were used.5 m. On the other hand the methods of casting the concrete have often employed a considerable quantity of sophisticated equipment of large capital cost which has enabled high rates of progress to be attained. have been used for medium diameter tunnels (Dusseldorf).bolted cast iron lining. Prestressed linings. 15. will increase the bending moments in the lining. The cast iron linings are often wider than conventional linings. The segments have machined joint faces which are bolted accurately to give face contact. The introduction of spheroidal graphite iron has enabled more economical sections to be designed as discussed in Section 4. For large diameter tunnels in rock cast in-situ concrete linings have often been used in Europe.2 m) and the Channel Tunnel service tunnel (1. in one or two cases. with sophisticated methods for the erection.these include the use of the Don-Seg lining for several tunnels in firm clay in Antwerp. A cast in-situ concrete internal structural lining was cast at a later date. hexagonal segments have been used with four segments t o the ring 6. In all these instances the segments were bolted to the previous segment or ring with longitudinal steel bars or bolts (see Fig. 04/03/2015. which had a five segment ring with a key segment.2 m). These segments are large. . usually of the concave/convex form. With the exception of the Channel Tunnel service tunnel. precast concrete lining was used of five segments with articulated joints for an 11 m diameter tunnel. have been used for diameters up to 8.2 m wide. expanded and then grouted. At the same time some European design methods have been modified to give lighter sections 14'. The lining acted as the ground support during the construction and on account of its thinness some cracking was allowed to occur t o increase the flexibility.1. Expanded concrete linings of the form used in this country have only been used in a few instances . and three segment rings have been used for diameters of 3 to 4 m. have been used but restraint of movement at the joint has often been incorporated.3. Uncontrolled Copy. thus giving fewer joints in the tunnel to be sealed. Both these methods. For many tunnels the precast concrete linings have been the primary lining or method of ground support and in-situ concrete linings cast inside. similar to those in the United Kingdom. such as dowel bars or. the methods of erection used in this country have been based on the conventional erector arm. 1. The thickness of the combined linings has thus been considerable and probably wasteful. although improving the stability of the lining in case of collapse. cast in reinforced concrete. the Mersey Kingsway Tunnels (1. In the United Kingdom segments of comparable width have been used in two instances. URS Infrastructure. 250 mm. Many such linings are much more costly than the UK corresponding ones and incorporate neoprene seals requiring greater precision in construction. In a small number of schemes in Europe. high tensile bars stressed across the joint. as internal linings. With the spiral lining the segments may be erected while the excavation is in progress with the shield shoved forward on the other three segments.2. The lining for the Elbe tunnel is of a hollow wave shape and of thinner cross-section than conventional cast iron linings (see Fig. Although precast concrete linings of the bolted form. where the segments are erected within a hoop of wire. have often been included for waterproofing reasons. Additional waterproofig measures have also been taken with the insertion of a membrane between the two linings. At Heitersberg a relatively thin. 2.2. Fabricated welded linings. A thicker lining may then be applied at a later date after the rock has deformed thus reducing the ultimate loadings. These methods have also been employed considerably for soft ground or weak rock tunnelling with purpose made shelds. Steel linings were used for the BART underground system in the United States where they were competitive.The Pont-a-Mousson lining for the French section of the Channel Tunnel which incorporates the use of small spheroidal graphite segments which are joined together to form larger segments with an epoxy resin has been discussed in Section 4. can be cast at a faster overall rate and with fewer scantlings than large segments. In Vienna the linings were used for tunnels of 5 m t o 8 m diameter with sophisticated mechanical methods of erection covering the full 360 degrees. were 1. . For tunnels in waterbearing strata neoprene gaskets are used in the joints which compress when bolted t o give a tight joint as discussed in Section 4. by the use of sophisticated mechanical methods of erection where the labour force may be fitters rather than conventional miners. Licensed copy from CIS: URS.1. These techniques have been introduced into Europe where they are now used considerably. however. 15. British engineers have had considerable experience of these support methods overseas such as the Kariba Tunnels and the Orange Fish Tunnel. URS Infrastructure. of 7.3. which are easy to handle and require no machining. on account of new fabrication methods. however.3. 15. with concrete linings. Uncontrolled Copy.3. 04/03/2015.2.3 but has been used extensively in Europe. Research is in progress on automatic methods of spraying where the rock is sprayed from within or behind the shield or tunnelling machine thus giving an immediate ground support with a thin lining which in suitable circumstances prevents weakening of the rock face. These forms of linings require more skilled erection in the tunnel with accuracy of erection being more important than speed of erection.3 Steel linings: In the United States where rock tunnelling predominates. This method is based on the principle that smaller segments.I25 m wide with 200 mm structural depth. steel liner plates are commonly used for ground support. have been used for tunnels in soft ground where large bending moments are expected or where their cost has been competitive with conventional grey iron linings.45 m diameter. The introduction of spheroidal graphite iron.4 Other forms of lining: The use of shotcrete with mesh reinforcement or rock bolts is little used in this country as discussed in Section 6. may reduce the use of steel as discussed in Section 4.1. This is partly offset. The station tunnel linings. in special corrosion resistant steel. It is perhaps in this field that there is greater need to extend the use of support systems which are lighter and cheaper than the steel arch system used nearly everywhere in British rock tunnelling until a few years ago. only one case of graphitic corrosion has been recorded. has a high compressive strength and a high resistance to corrosion. which has been used for tunnel linings since 1869. Until recently the grade of grey iron used for tunnel linings was Grade 10. Graphitic corrosion. grey iron and spheroidal graphite iron.1 Grey iron Grey iron.coal dust in anthracine oil . the tunnel was driven in clays. The majority of these have been tunnels in London Clay but in the case of the first Blackwall Tunnel. showed no signs of corrosion when a section was reconstructed after bomb damage in late 1940 47.5 mm diameter or plates of approximately 15 rnm thickness. extract of which is given in Table 22. and inhibits the activity of sulphate reducing bacteria associated with anaerobic corrosion. During the last 10 years several of the tunnels constructed during the period 1880-1905 have been inspected or dismantled during the construction of new works and in all cases. but Grade 12 is now usually used having better strength characteristics. URS Infrastructure. the linings have shown no signs of corrosion. t o extend the life of cast iron considerably. Bitumen paint has been shown. 04/03/2015. 34). Grey iron tunnel linings were originally coated for protection with Dr Angus Smith's compound . APPENDIX 3 Cast iron and steel tunnel linings Two forms of cast iron are now available for tunnel linings. Tensile strength depends upon the thickness of the section cast.and the machined faces coated with red lead. which is the corrosion of the iron particles in the cast iron leaving a graphitic corrosion residue has.16. These materials and their manufacture are discussed below. The mechanical properties of grey iron are given in British Standard 1 4 5 2 : 1 9 6 1 ' ~ ~an. Licensed copy from CIS: URS. although higher grades are sometimes specified. been recorded on a number of occasions with cast iron pipes. Grey iron derives its name from the grey crystalline appearance of its fractured structure due to the presence of free flake graphite. on account of the rate of cooling following casting .the thicker the section the lower the tensile strength (see Fig. 16. The Beaumont Tunnel for the Channel Tunnel scheme. however. These properties are those for round bars of 30. including heavy duty bitumen paint with epoxy resin primer on the external surfaces and zinc silicate primer on the internal faces. in laboratory tests on pipes. Although cathodic reactions can occur between iron and the free carbon this process is thought to be comparatively slow with tunnel linings. The outward appearance of the cast iron is changed little and with no apparent wasting but the soft black graphitic residue can be readily scratched away. Tests have been carried out on samples with various concentrations of acid to accelerate this process. wax or grease which can easily be applied on site. The alkaline environment of the cement (or lime) grout on the outside of the lining is found to neutralise much of the corrosiveness of the ground conditions. The corrosion of grouted grey iron in tunnel linings is usually very slow and is thought t o have a negligible effect on the strength. In overseas contracts more stringent and expensive paint specifications are often called for. constructed . with the exception of the Beaumont Channel Tunnel discussed below. Although many tunnels have been constructed with grey iron linings in a sea water environment and a number have been inspected after periods of up to 70 years. silts and gravels using compressed air. built in 1869 in London Clay. Uncontrolled Copy. Both of these coatings are now seldom used and the segments are usually dipped in a form of bituminous paint and the machine faces left uncoated except for oil. which was constructed in 1892-97. The Tower Subway under the Thames. 0 1% proof stress 0.1 % proof stress Ultimate stress Strain a t failure Compression 0.58% in the early 1880's.26 52000 0. allowing water to enter the tunnel. Once the lining is in its permanent position and fully grouted.26 0. Property (stresses and moduli in M N / ~ ~ ) Tension 0. URS Infrastructure.6% t o 0.26 4 1000 0.65% 74 171 263 87 200 620 102 240 690 120 280 765 145 343 875 103000 1 12000 45000 0. except in very poor ground near t o the ground surface (h < d). Uncontrolled Copy. Methods of sealing these joints are discussed in Chapter 9. handling and erecting of the segments. During the temporary stages of stacking. Grey iron is a brittle material which cannot take high tensile stresses.7% 60 140 216 0.5% to 0. Failures of grey iron linings in the permanent condition seldom occur mainly on account of the high factor o f safety. These rings are believed t o have been placed in the tunnel for additional support in 1890 and were not grouted. the tensile stresses are insignificant and the ring is mainly in compression. The percentage of breakages is small. Sound grey iron lining is impervious and ingress of water is normally confined to the joints although occasionally blowholes can occur particularly at the corner between the skin and the flange. normally 4 t o 1 0 .4% to 0.1 % proof stress Ultimate stress Elastic modulus E Shear modulus G Poisson's ratio Grade 10 12 14 17 43 100 155 0.01 % proof stress 0.26 120000 130000 48000 0. less than 1 per cent. as a result of the design requirements for the . and while the shield is shoved forward much more severe stress conditions can occur causing damage t o the segments. for medium and small diameter tunnels and even less for large diameter heavy segments which are not manhandled a n d which require mechanical means of erection. inherent in the permanent condition.TABLE 22 Mechanical properties of grey iron 146 Licensed copy from CIS: URS.to have traces of graphitic corrosion. The joints can be caulked to give a substantially dry tunnel which in most circumstances would be drier than a tunnel constructed with other forms of precast lining. transporting.75% 51 120 185 0. The single cast iron rings spaced at intervals along the tunnel were foundafter analysis. The outer and inner surfaces showed little corrosion but an area in contact with the chalk marl showed considerable corrosion along the edges of the flanges. was dewatered in 1974 for instrumentation work on the Stage 2 Channel Tunnel contract. however. 04/03/2015. With the introduction of spheroidal graphite iron more precise methods of testing raw materials and molten iron are required to obtain the purer material. Normally remedial measures can be carried out to repair damaged flanges but in the very rare cases of a cracked skin it may be necessary to replace the segment. to avoid reducing the sections beyond the limit required for other factors such as buckling or overstressing at the base of the flanges. The final section may be dictated by the minimum casting thicknesses to allow the material t o flow in the mould.2 Spheroidal graphite iron The techniques of manufacturing spheroidal graphite or ductile iron were developed in the late 1940's as a result of metallurgical research. 16. The manufacturers. The material is less brittle than grey iron. The linings may be designed to take advantage of the tensile strength of the material t o give a balanced economic section in its permanent condition in contrast to the high proportion of low stressed areas found in grey iron linings. however. Uncontrolled Copy.3 Manufacture of cast iron linings Traditionally green sand moulding methods have been used for the manufacture of cast iron segments with cast iron master patterns (see Plates 54 and 55). The conventional channel section for grey iron can thus be much improved.2). sulphur and phosphorus are reduced. Any damage normally occurs at the flanges often on account of birds-mouthing at the joints due to incorrect building since the lining is not designed as a rigid ring and the load is then taken in compression in the skin. The main problems have been in the design for the shield thrust. . are confident that the life of spheroidal graphite iron. Table 23 gives the mechanical properties148 and the matrix structure of spheroidal graphite iron for the grades most suitable for cast iron linings. The handling and erecting stresses are not so critical with spheroidal graphite iron and breakages can be assumed to be very small. When. being similar t o its compressive strength. Alternatively. the short period since its introduction has not yet permitted long term assessment. the lining may be temporarily supported or in the case of possible severe deformation. Spheroidal graphite iron has the mechanical properties of steel and is easy to cast and machine. The improved mechanical properties would moreover help to redistribute the stresses due to any localised corrosion and also allow the material to deform plastically without failure. similar to an articulated lining. however. 16. URS Infrastructure. the bolts may be slackened under strict control t o form a lining with articulated joints (see Section 7.Both these methods are applicable to grey iron or spheroidal graphite iron. The chemical composition is similar to grey iron except that the impurities of manganese. Spheroidal graphite iron has been shown in laboratory tests t o have a higher corrosion resistance than grey iron. the lining may be infilled with concrete t o increase its rigidity and the joints sealed with glass fibre reinforced resins or other waterproofing sealers. Licensed copy from CIS: URS. Care must be taken. 04/03/2015. for handling and shoving of the shield. after allowing for the reduced section thickness. It has a slightly higher compressive strength than grey iron but its tensile strength is much superior. However.temporary conditions. will be similar to that for grey iron due to the higher corrosion resistance. during the construction of adjacent works i t is anticipated that possible damage may occur. The flake graphite form of grey iron is changed to spheroidal graphite by the addition of very small proportions of cerium or magnesium. More recently larger segments or tubbings which require more rigid moulding materials have been cast using self setting sands based on furan resins or sodium silicate used in conjunction with carbon dioxide 1497150. 275 Elastic Modulus E Shear strength Poisson's ratio Note: British Grades BS 2 7 8 9 : 1 9 7 3 l ~ ~ The matrix structure shows the form the carbon takes on forming with the pure iron. For grey iron castings the moulds after casting are cooled for half an hour before demoulding. Templates are normally used for measuring these tolerances which due t o difficulties in specifying the datum surface require a lengthy and complicated specification. The radial flanges of the segments are machined singly or in groups of three. URS Infrastructure. Stresses and Moduli in MN/m2 Ultimate stress Licensed copy from CIS: URS.5% proof stress 272 340 35 1 3 60 288 360 382 414 3 18 39 7 425 468 169000 450 0. the circumferential flanges.275 176000 630 0.1 % proof stress 0. segments.275 174000 540 0. The tolerances specified for cast iron linings are generally more stringent than those associated with other cast iron products. With spheroidal graphite this c o o h g period may be longer depending on whether artificial cooling methods are used. to avoid distortion of t h e thinner. Countersinking can be done simultaneously or as a separate operation.1% proof stress 0. Uncontrolled Copy. 04/03/2015.2% proof stress 0. and often larger. if required.5% proof stress Elongation at failure 194 32 3 339 359 7% 208 346 372 409 3% 231 385 416 462 2% Compression Limit of proportionality 0. With the introduction of more carbon the strength increases and the matrix becomes darker. Magnetic crack detectors and ultrasonic testing are now specified for the inspection of spheroidal graphite iron. With grey iron segments only a small percentage of the castings are inspected and checked using a template. being machined singly.TABLE 23 Mechanical properties of spheroidal graphite iron 148 Property. The segments after fettling are dipped and stored if necessary ready to be machined.2% proof stress 0. b u t with the thinner sections in spheroidal graphite iron it is essential t o ensure that no defects are present within the casting. The basic orders of the main tolerances are given below b u t these d o not constitute a specification as such:- . The structure contains white Ferrite and dark Pearlite. Bolt holes are drilled singly using preset formers or alternatively using special machines capable o f drilling half the holes on all four flanges simultaneously. Matrix structure 50017 60013 70012 Mainly Ferrite some Pearlite Mainly Pearlite some Ferrite Pearlite Tension Limit of proportionality 0. unprotected steel will corrode at the same rate as unprotected cast iron. Different treatment may be required to the flanges and to the main body of the segment and additional protection may be required in the tunnel.9 and the special bolted segments at openings. welding of adjacent flanges. to be painted or coated if left exposed to. pitch circle diameter and for the master ring. the first two of which are the only forms likely t o be used in tunnels.85 Mg/m3 7. The grout around the periphery of the bolted form of lining gives an appreciable water barrier as in other forms of bolted lining. In general. No comment is made here on the paint specification as these are covered by other publications and are always being updated due to improved methods. The main exceptions have been the expanded linings used in the LTE Victoria Line. The steel segments themselves are impermeable except when faulty welding occurs during fabrication. Where treatments are used thought should always be given to damage during construction and its means of rectification in-situ. tolerances are specified for thickness of metal. therefore. This treatment is costly and time consuming and may well be the critical factor in the production of the segments. In general.damp or corrosive conditions in the tunnel. . When liner plates are not encased in concrete and form a structural lining these should be galvanised or painted with a protective coating. although there may be a protective skin on the surface of the cast iron which will reduce the internal attack.4 Steel linings Structural steel is generally available in three forms.Length of segment Width of segment + 0. the erection times are quicker due to the reduced weight of the segments. URS Infrastructure. There is little direct information concerning corrosion of steel tunnel linings since very few of the older tunnels were constructed with this material.000 M N / ~ ~ Steellinings can be caulked or waterproofed as effectively as cast iron linings. 16. bolt holes. The damage to the segments during handling or erection is negligible.85 Mg/m3 YOUNG'S MODULUS 200. high yield steel and weather resisting steel. 04/03/2015. On the outside of the bolted linings the grout acts as a protective coating. the steel linings used in the United Kingdom have been subsequently encased in concrete. Licensed copy from CIS: URS.5 rnrn for cast surfaces Depth of segment +- 3 mm up t o 6 m diameter + 5 mm above 6 m diameter In addition. which are much thinner than the fabricated bolted steel lining and act only as a temporary lining. Uncontrolled Copy. The tolerance for the diameter of rings built on master rings is +.6 mrn for rings up t o 6 m diameter and + 10 mm for above.5 mm for machined surfaces + 1.5 mm + 0.2 and 16. The physical properties of mild steel and high yield steel are YIELD POINT Mild steel High Yield steel 240 M N / ~ ~ 345 M N / ~ ~ ULTIMATE DENSITY 43015 10 MN/m2 4901620 MN/m2 7. will form a watertight seal. With steel liner plates. although expensive.000 MN/m2 200. In dry environments. Steel linings require. as discussed in Sections 4.2. mild steel. Fabricated bolted steel lining can be erected in a similar manner t o cast iron linings with some saving in time on account of their slightly reduced weight. 147. ". 16. and 1835 t o 1 8 4 3 was rectangular. . Clearly the name tubbings derives from the replacement of timber staves with walings. When a tunnel was constructed using a shield it was found that a brickwork or masonry lining was not ideal due to the time required for the lining t o obtain sufficient strength not only for the ground load but also for the shield ram forces. Licensed copy from CIS: URS. In t h e first stage the corners and bolt holes are punched out of the flat sheet. The first scheme proposed was of a circular cross-section and a cast iron (grey iron) lining would have been preferred if the scheme had been adopted." ". Marc Isambard Brunel in the patent151 for his shield in 1818 proposed that it be used in conjunction with a cast iron (grey iron) lining. The cast iron (grey iron) lining was first used in a tunnel as a permanent lining in 1869 in the construction of the Tower Subway under the Thames 16. In 1795 "tubbings in circles" were used for the first time for a shaft lining at e l ~the following year tubbings made of grey iron lined the shaft at Percy Main the Walker Colliery on ~ ~ n e s i dand Colliery. quicker and easier to erect and was capable of taking the radial and longitudinal forces immediately. Grey iron tubbings or segments have subsequently been used for many shafts in waterbearing strata. . although the joint details continued t o evolve during the first 50 years. which is then followed by the formation of the corrugations on the skin of the segment and the forming of the flanges by pressing the flat sheet onto a master former. The third stage entails pressing the liner plate to the correct radius. which I propose t o line afterwards with brickwork or masonry. This form of tunnel lining has now been used for over 100 years and the details of many grey iron linings today are very similar to those develaped for the first few tunnels. The liner plates are formed from sheet steel in a three stage process." This was the first mention of a cement grout t o fill the void between the lining and the ground. In contrast the cast iron (grey iron) lining was t h n n e r . . . . 04/03/2015.Steel segments are normally fabricated from sheet metal and welded and thus their manufacture is more labour intensive than cast iron segments. . The space. ". A number of tunnelling schemes using cast iron (grey iron) linings are briefly mer-.5 Bolted grey iron linings Cast iron linings. . of grey iron.tioned below to illustrate t h e development of the lining details." The cross-section of Brunel's Thames ~ u n n e l atl ~Rotherhithe constructed during the periods 1825 to 1828. The earth is continuously removed from within the cylinder (the shield) and the cylinder is from time t o time forced forward a short distance t o admit a ring of iron being put together within the inner end of the cylinder. such iron rings being of strength suitable for forming a permanent lining to the tunnel. In 1 8 6 4 P W ~ a r l o w " took o u t a patent for an improved method of constructing railways in tunnels using a shield moving forward in one unit. Data for many of the linings are given in Table 24. were first used as permanent linings in shafts some 75 years before they were used as permanent linings in tunnels. URS Infrastructure. . as it is left between the earth and the exterior of the tunnel may be filled by injecting or running in fluid cement. The body o r shell of the tunnel may be made of brick or masonry but I prefer t o make it cast iron. . . Uncontrolled Copy. These rings.14 m internal diameter. 36). In waterbearing strata the joints were caulked with "iron cement" while in London Clay they were pointed with cement. segments were cast in compressed sand moulds in specially designed machines using hydraulic presses each of which was capable of manufacturing 1 3 or 14 segments. The grouting o f the void between the ground and the lining was carried out using a hand syringe with lime and water mixed in a t u b . and the pressure was insufficient to obtain a complete envelope around the tunnel. O n the external face of the lining 51 mm deep circumferential flanges were provided t o key the lining t o the concrete (see Fig. The rings were erected by hand with soft pine timber packings. The flanges were not machined and the circular bolt holes were cast into the flanges (see Fig. were lined in grey cast iron.1 m and 3. Uncontrolled Copy. to enable it t o flow through the syringe. The. THE CITY AND SOUTH LONDON RAILGAY(1 886 t o 1907) l' designed b y Greathead and The shields for the construction of the City and South London ~ a i l w a ~ were were the forerunners of what we now know as the "Greathead" shield incorporating many of the essential features which have survived to the present day. about 1890. The lining.6 m vertical by 2.2 m horizontal with an internal grey cast iron lining of internal dimensions approximately 1. URS Infrastructure.6 m.4 m with 0. about two rings. in the longitudinal joint and with a rope of hemp or hard wood packing in the circumferential joint.31 m thick peripheral concrete on the outside of the lining. The segments after casting were dipped in hot pitch and tar. per hour. rings were used to act as additional supports t o the timbering already in position. was a structural lining although acting as a permanent shutter for the concrete. The circumferential flanges were 7 6 m m deep while the radial flanges were 102 m m deep. The rings were uncovered recently when the Beaumont tunnel was opened up during the Stage 2 works for the Channel Tunnel.7 m by 1. the shafts mainly in cast iron and the stations entirely in brickwork. 6 mm thick. Rings. When. the contractor. were 0. which consisted of four segments with machined radial flanges. of 2. 04/03/2015.singly or in pairs at intervals down the tunnel and made up of four segments and a key are reported to have been used to seal the ingress of water at fissures in the chalk. 38). iron packings were . The tunnel which was of 2. during late 1940 and early 1941. The results were not thought at the time to be satisfactory as the grout was too fluid. which were 3. The excavated diameter was approximately 2. from an original design by P Barlow and was the first use of a shield of circular cross-section.51 m wide consisting of three long segments and a key segment (see Fig. I n the late 1870's this culvert was abandoned and a new tunnel constructed through the millstone grit and shale beds. The average daily progress of the tunnel construction was 2. The running tunnels. CHANNEL TUNNEL (1 882 to 1883) Grey cast iron was used as a temporary support in the construction of the Beaumont pilot tunnel for the ChannelTunnel.42 m internal diameter was h e d in rings 0.61 m wide and consisted of four segments but with n o key (see Fig.Licensed copy from CIS: URS. 37). 35). the tunnel was repaired following bomb damage the grout was found in nearly all cases to have formed a complete envelope t o the lining 147. On curves. STUBDEN RESERVOIR OUTLET (Late 1870's) The Stubden reservoir16 was constructed in about 1860 with a culvert outlet. TOWER SUBWAY (1869) The Tower Subway 16y147was constructed using a shield propelled by screw jacks designed b y J H Greathead. At a later date.2 m internal diameter. London Clay London Clay.4 22.9 4.2 25.51 0.1 56 38.6-31.60 305 39-60 36 - - 16 +key - 0.8 - - The special linlng for the waterbcaring strata.2 25 31.1-50. of segments Wt.8 38. Uncontrolled Copy TABLE 24 Conlparison of cast iron linings Date Tunnel Length 111 Sn~allDiameter (up to 3 n ~ ) Tower subway Abcrdccn Dee T u n ~ ~ e l London Transport for vec~tilationand other small dianleler tunnels Victoria Line Fleet Line Medi~rntDion~eter(3-6 m ) City and South London 1869 1904--09 403 101 Strata Cover m Internal Diameter Ring width m m flange Width of flange Thickness of flange mm mm mm Depth Of No.76 0. London Clay.4 22-25 1886-90 4030 6340 25 25 London Lea out fall sewer Clasgow Underground Waterloo and City 1891-92 1892-95 1894-95 - - 1895-1900 1899-1906 1899-1901 3.8 34.51 Central London Baker Street and Waterloo " 1 Greenwich London Clay and waterbearing gravels Ballast Peaty clay Alluvial deposits London Clay Waterbearing ballast London Clay Waterbearing gravels Waterbearing ballast.51 0.7 25. of bolts No.9-38.6 8 mlweek 3 mlday - abovc) 30 Progress 1.per metre run tonnes 7-20 15 LondonClay Alluvial clay 2.6-38.4 25.5 50.61 364 38.6-31.8 25.8 38.r (6 Ulackwall *I 11.2 19-25.1 I4 + key 22.46 0.46 0.5 deposits 0.56 3.1 48 38.5 3.4 356 38.60 47 47 29 46 57 57 6tkey 6tkey 6tkey 9 +key 7 +key 7 +key 2.2 34.51 0.2 50.7 70 70 79 38.8 38.3-66.60 102 110 28. alluvial deposits 8.51 0.4-28.3 40 33.7 36 16tkey 24 +key 21.13 2.76 254 305 356 38.8 25.4 Bunter sandstone Glacial deposits Chak.9 7 t key 8 t key 3.1 I 2 + key - 0.Licensed copy from CIS: URS.II tforrl 1)uplicalion 1972-78 2x420 C1 273/Cl 7-30 London Transport V~ctoriaLine I:lcet Line 1963-69 1972-75 - - Large Diantivc.46 0.8 38.6-31.1 72 44.45 Clay.0 0.48 0.54 Boulder clay Chalk.4 25.1-50.1 38.1 64 31.1 - 330 38.2 22.8 2. sand mottled clay 0.56 3.5-23.8 44.61 305 315 41.5 13.sandy clay and gravel 13. of circle bolts Dia.54 1.1-50. URS Infrastructure.25 0.1 50. alluvial 9.4 43 21 19 25.76 0.1 23. 04/03/2015.0 0. 41. 9.1 38. 9.51 0.76 360 38.6 beds.4 3+key 5 +key 1.6 25.2-25.8 31.8 28.0 39-55 111 72 31.83 3.8 or 54.1-63.34 0.8-76.93 19 22 56 24 19 20 6 +key 6 t key 1.61 0.2 22.6 6000 5491 6-25 20 19000 12200 361 - 3-17 1963-69 1972-75 - - 1892-97 950 2-25 Rotherhilhe 1904-08 1125 3-17 Mersey Queensway *2 1925-34 1587 17-34 1)artford 1956-63 1429 6-2 1 Clyde 1957-64 2x760 6-40 Blackwall Duplication 1961-67 1 173 6-2 1 I'ylle Tu~lnel 1961-67 1688 6-33 Mc~scyKingswaytu~~ncls 1967-74 I).6 Sandstone.6 22.4 28.51 0. Woolwich and Reading beds '2 9.4 22.46 341 96 38.51 0.4 15 +key 26.1-50.6 3.88 3.0 Boulder clay.18 2.46 0.47 2.sand.2 24 6tkey 8 t key 3.8-69.1-56.8 38.6-31.8 53 47 19 I9 22.66 3.5 glacial deposits Buntersandstone.1-54.46 76.76 0.6-31.6-38.0 38. shale.5 nllday 3 rnlday max.76 0.6-31. gravel Coal measures and 9.3-50.5 rnlmonth - 3.8 25-30 25 25 36 32 22.7 3.1 38.7 38.5 50.1 14 +key 14 t key 16 t key 19.8 28.9 23.61 1963-69 1972-75 - - London Clay London Clay 2.8 16tkey 21. 10 ~nlweek average . silt and sand Woolwich & Reading 8.102 I27 20.58 0.46 114 114 111 152 130 130 124 124 152 28.1 London Transport Victoria line Fleet Line London Clay London Clay Woolwich and Reading beds 3.2 22.26 3.60 102 100 22.50 The main section of tunnel. - 25 22-24 22.14 9.46 0.1 3.1 24 + 2 keys 12 +key - 360 38.46 0.7 0.63 8.24 7.85 0.72 Ballast London Clay 7.8 28.1 48 38.5 41.1 28.2 3. The joints were machined and had caulking grooves which were sealed with iron filings and sal-ammoniac. were not rolled so did not break joint.5 mm.74 m internal diameter is of interest mainly for the details of the flanges. The segments were 0. and the thin skin thickness of 17. was made up of nine segments and a key.56 m grey cast iron lining while for those of 3. Soft wood packings were used in the joints and when not completely watertight the joints were wedged with oak wedges.which is thin for grey iron segments which are normally of a minimum of 19 mm. the segments being shorter in circumferential length than previous linings approximately 1. Licensed copy from CIS: URS. Extensions were constructed to the north to Euston and to the south to Clapham Common during the next seven years in the original 3. 42). The void between the lining and the ground was grouted using a compressed air grout pan patented by Greathead in 1886 and very similar to that in use today. A shield was then used and the tunnel relocated but this was abandoned after only 49 m. in ballast.used. (see Fig.2 m internal diameter the old lining was reused with five small castings in the joints (see Fig. THE BLACKWALL TUNNEL (1892. Uncontrolled Copy.15 m internal diameter grey cast iron linings. The longitudinal and circumferential joints were not machined. 39). .1892) ~ ' originally ~ commenced without a shield and was abandoned after This tunnel under the River ~ e r s e was 18 months when only 18 m had been driven. being cast with a small fillet at the back of each joint. which took approximately 1%hours to erect. Those sections of 3. 41).63 m internal diameter for the length under the river (see Fig.82 m and made up of five cast iron segments. 04/03/2015. The rings. Yach ring.1 m internal diameter were lined in new 3.36 rn internal diameter. the bottom three with their flanges inwards and infilled with concrete and the top two with their flanges outwards. This section was egg-shaped. The segments were also cast with a larger curvature fillet than normal between the flanges and the skin.56 m internal diameter and a number of stations enlarged in length and diameter. The tunnels were lined with 8. 0. 2.23 m external diameter grey cast iron lining using a light section of 7. J F Deacon.76 m wide. URS Infrastructure. The station tunnels were constructed in 6. In 1900 part of the original tunnel between the Monument and the south side of the Thames was reconstructed to improve gradients and curves in 3.46 m wide.2 m internal diameter lining.5 m internal diameter giey cast iron lining. THE GLASGOW UNDERGROUND (1892-1895) Those sections of the underground149 in soft material were lined in cast iron of 3. 40). VYRNWY AQUEDUCT UNDER RIVER MERSEY (1888.7 m and 9. EDINBURGH MAIN DRAINAGE (1 890) ' ~ of a circular cross-section with the exception of a short The interceptor sewer constructed at ~ e i t h was length at Leith Docks which was in bad ground and subject to internal pressures due to tidal action.72 m internal diameter for the length under the land and a heavy section of 7. The segments were cast in machine moulds f i e d with sand and had a capacity of between 3 0 and 36 segments per day. The lining was backed with concrete (see Fig. without a pilot tunnel. London Clay and chalk with the use of shields and compressed air. The shield was then reconstructed and the tunnel of 243 m in length completed under the direction of the Engineer.1897) The Blackwall Tunnel 17 was constructed from four shafts.29 m by 2. In 1922 to 24 the tunnels were enlarged to 3.2 m long. The tunnel of 2. 56 m internal diameter had unmachined flanges with creosoted pine timber packings in the longitudinal joints and tarred hemp rope in the circumferential joints. The running tunnel lining which had machined longitudinal joints only. three rings of brickwork were built to complete the ring with an internal diameter reduced below axis by approximately 105 mm. 43). The crossover tunnels were . One of the tunnel drives in 1897 was excavated using a Price's bucket machine in the face of the shield but d u e t o electrical and other faults the overall progress was n o greater than that of the hand excavated tunnels although the machine had a capacity t o excavate the tunnel in about half the time of that for hand excavation. This section o f the London underground16 was constructed in 3. The lining was unusual being made up of eight segments and two keys. T H E GREAT NORTHERN AND CITY RAILWAY (1898. in waterbearing strata the joints were made with 19 mm diameter rubber packings and soft wood packings which were later removed and caulked with neat cement.88 m internal diameter grey cast iron lining in waterbearing strata from there t o Waterloo Station. The running tunnels of 3.07 m internal diameter. The longitudinal flanges were n'ot machined and soft wood packings were inserted in the joints. T H E WATERLOO AND CITY RAILWAY (1894-1895) Licensed copy from CIS: URS. The longitudinal joints were machined without a caulking groove while tarred hemp rope was placed in the circumferential joint and pointed with cement mortar. one in the crown and one in the invert (see Fig. T H E CENTRAL LONDON RAILWAY (1895-19 12) This section of the London underground from Wood Lane to Liverpool Street was opened in stages from 1 9 0 0 t o 1912 1 6. The joints were later pointed with cement mortar (see Fig. The station tunnels were generally 6. This was the first time this had been written into a contract. There was little reduction in the levels of noise and vibration set u p by subsequent traffic. after excavating for a further 102 t o 127 mm in depth. had no caulking groove for those sections in London Clay and a 19 m m deep groove for those sections in waterbearing strata. After building a section fully lined in grey cast iron. It was specified that the longitudinal joints for both the running and station tunnels should break joint. Uncontrolled Copy. Wood packings were used on curves. Each ring was erected in about 20 minutes. URS Infrastructure. 45). the lower half of the cast iron lining was removed in stages and.46 m'and 7.47 m internal diameter and were excavated using a shield and lined in grey cast iron. O n curves steel packings. Base plates were fitted to the cast iron lining at t h e junction between the cast iron and the brickwork. 44). The station tunnels were of 6.9 rn internal diameter grey cast iron and brick lining was opened in 1904. The bolt holes both in the longitudinal and circumferential flanges were cast elliptical (see Fig. this was probably more than offset by the additional cost of excavation and brickwork. Although there was a considerable saving in grey cast iron.The tunnels were constructed using a shield and compressed air and the forward heading process was used with excavation being carried out for one t o three rings at a time. In London Clay the circumferential joints were made with tarred hemp rope and creosoted timber packings which were later pointed with neat Portland Cement. 04/03/2015. were used. two per segment.7 m internal diameter cast iron lining between Mansion House and the South Bank of the Thames and in 3.1904) This underground railway between Moorgate and Finsbury park16 of 4. where no lead washers were used and the caulking was with rust. similar to the Greenwich Footway Tunnel. The tunnel was constructed mainly in the Woolwich and Reading beds. grey sand and mottled clay. additional types of segments were therefore required. was opened in stages from 1906 to 19 15. All caulking grooves were later sealed with rust.6 mm on the diameter. This was the first time that the flat bottomed lining was used. to seal the ingress of water. The longitudinal joints were then machined with a caulking groove taken down behind each bolt in turn. south of the Thames. 0. In the London Clay a standard 0. 47). this special lining had machined longitudinal and circumferential flanges. which made it difficult t o seal the periphery of the lining in waterbearing strata. these were machined to give a variation in width of 28. were used. The lining for the land section of the tunnel had a 44. THE ROTHERHITHE TUNNEL (1 904.66 m internal diameter were mainly in London Clay with one section under the Thames in waterbearing gravels.with both flanges machined. The rings were erected t o break joint. The lower segments were not provided with grout holes. The quantity of water pumped from the tunnel when the caullung was complete was between 750 and 1100 1 per day. the equivalent figure was 0. THE GREENWICH TUNNEL (1899.constructed in 9.8 mm (see Fig.072 l/m2 of tunnel per day. shaped t o fit behind the bolts. For the east tunnel the joints were redesigned mainly to improve the caulking details. tapered rings were used. This section of the London Underground l63ls2 between Queens Park and the Elephant and Castle. URS Infrastructure.1908) otherh hit he'^^ road tunnel under the River Thames between Stepney and Rotherhithe was built in The 8. The washers and lead wire worked effectively and very little recaulking was required when the compressed air was taken off.5 1 m width. and soft lead washers inserted t o seal the bolt holes. 48).1 5 m internal diameter flat bottomed grey cast iron lining . which is equivalent to approximately 0.27 l/m2 of tunnel per day.45 m internal diameter grey cast iron lining with an internal concrete lining of 8. equivalent to between 0. The bolt holes were machined with bevelled ends and lead washers were placed below the bolt washers.5 mm thick skin and for the river section a thickness of 50. tapered from 13 mm to 16 mm. For the Blackwall Tunnel. The bolts were bevelled. The flanges were all machined with caulking grooves on the internal edges which were sealed with lead wire and rust. For the west tunnel. which extruded into the bevelled ends of the hole.27 l/m2 of tunnel per day. On the Holborn .18 and 0. The lining was heavier than for other similar tunnels and with larger diameter bolts (see Fig. The running tunnels of 3. 46). Where the circumferential joint was not machined creosoted pine packings. The machined faces were painted with red lead and Stockholm tar.76 m. the first to be driven.19 15) Licensed copy from CIS: URS. The grey cast iron lining was similar in many respects to the Blackwall Tunnel and with the same width of ring. For curves. similar to the circumferential joint for the west tunnel. Uncontrolled Copy.61 m wide ring was used while for the river section a special lining was designed of 0.a ring with a larger radius for the lower half than the top half . THE BAKER STREET AND WATERLOO RAILWAY (BAKERLOO) (1 899.58 m was driven through waterbearing ballast. When the caulking was complete approximately 2 150 1 were pumped daily from the tunnel. The flanges were machined with caulking grooves on the internal edges which were sealed with lead wire and rust. The longitudinal joint had a caulking groove of a constant depth while for the circumferential joint the groove was taken down behind each of the bolts in turn (see Fig.24 m internal diameter.1901) The Greenwich16 footway tunnel of internal diameter 3. 04/03/2015. 82 m internal diameter pilot tunnel. the Clyde ~ u n n e (1957-63). the other in expanded grey cast iron lining.46 m wide and both the longitudinal and the circumferential flanges were machined and caulking grooves provided. The station tunnels were generally of 6. 1 ~ ~ ~ the ~ Blackwall ~ ~ Duplication ~ ~ u n n e l " (1961-67). one in the crown and one in the invert. l .4 km of bolted concrete lining (see Section 5.162 by the Victoria Line and Brixton Extension. ~ the Tyne ~ u n n e l " ~(1961-67) with grey cast iron linings for the whole driven length of the tunnels and the Mersey Kingsway Twin Tunnels 8*160.1 m of tunnel was lined per day with an excavation rate of 2 0 minutes per ring in good ground rising t o 45 minutes per ring when rock was encountered.1 m m thick and n o feathers were cast t o strengthen the flanges (see Fig. 0. constructed. The skin was 38. The tunnel was constructed with the aid of a 3. this method of sealing the bolts was not initially successful and all the bolts were resealed with tarred yarn grurnmets and soft lead washers. RECENT ROAD TUNNELS Six road tunnels under rivers have been constructed during the last fifteen years or are under construction in the UK using cast iron lining for part or the whole of their driven length. Similar Price machines. MERSEY QUEENSWAY TUNNEL (1925-1934) The under river section of the Mersey ~ u e e n s w ~a ~u n n e lwas l ~ lined ~ in 13. Details of these linings are given in Table 2 4 and Figs 50 to 53. Feathers were provided in all instances between bolt holes t o stiffen the flanges.83 nl internal diameter.tramway tunnels constructed at the same time.2 rn of tunnel per day. The thickness of the skin in all the linings was 38. only certain sections of which were below ground level. The running tunnels were generally in 3. A band of rock was encountered during the drive which slowed the progress.46 m t o 0. 49). LONDON TRANSPORT EXECUTIVE MORE RECENT SCHEMES (1935-to date) The LTE carried out a large programme of reconstruction between 1935 and the early 1940's which included the Ilford extension of the Central ~ i n ethe ~ extension ~ . The branch tunnels were of 8. the latter being excavated with a mechanical shield manufactured by Messrs Price and Reeves.71 m or 3.61 n~wide except at special sections where it was 0. Uncontrolled Copy. one part in expanded In 1960-61 the experimental length of the Victoria ~ i n e ~was concrete lining. but the width of the rings varied from tunnel to tunnel within the range 0.1 m m .6 m internal diameter cast iron lining except for 4.07 m internal diameter grey cast iron.76 m. These are the Dartford Tunnel 155 (1956-63). 04/03/2015.4 rn internal diameter grey cast iron lining while the land sections were of semicircular upper section in grey cast iron . This was followed in 1963-6919>22j23.1 61 (1 967-74) and the Dartford Duplication Tunnel (1972-76) with grey cast iron linings for part of the driven length. of the Bakerloo Line north of Baker Street to Stanmore and the extension of the Northern Line north of Archway t o High Barnet.1 m internal diameter grey cast iron lining or of steel ribs and concrete with a concrete invert.4). The lining was 0. Those sections of the running tunnel in conventional grey cast iron bolted linings were of 3. All these linings had machined longitudinal and circumferential flanges with caulking grooves on the internal faces.46 and 7. Licensed copy from CIS: URS. but an average of 4. As the upper half of the lining was erected first the lining had two solid keys. For these linings only the longitudinal joints were machined . URS Infrastructure.6 m below the crown of the main tunnel. which were originally introduced for the construction of underground railway running tunnels from Charing Cross to Hampstead (1903-1907) reached a maximum rate of progress of 5.or steel ribs and concrete with a flat bottom concrete invert. 00 1.50 8.50 10.90 7. the standard linings used for the LTE tunnels have been employed except where a heavier lining was required.85 4. Uncontrolled Copy.25 10.00 CABLE.25 3.85 m internal diameter and the standard station tunnel 6. When the LTE tunnel linings were redesigned to metric sizes for the first stage of the Fleet Line and the the~ opportunity ~ for more standardisation was taken.75 2. These linings were designed to be machined on both the longitudinal and circumferential flanges but due to programme difficulties the circumferential flanges were machined on a relatively small number of rings.75 6.21 4.93 2.33 6.85 4.50 7.oo 5. one with machined circumferential flanges.The statioii tunnels were generally 6.66 2.50 5 .45 3. 54. Details of the metric linings used in the first stage of the Fleet Line are shown in Table 25 with details of the joints in Fig. SEWER AND OUTFALL TUNNELS A number of cable.25 9.60 m which enabled a reduction to be made in the weight of grey cast iron per metre of tunnel for the larger diameters (see Table 25). The width extension of the Piccadilly Line to ~ e a t h r o w of all rings was increased to 0.98 8.5 m internal diameter. Two types of lining were available for all tunnels above 3. the other with unmachined circumferential flanges. TABLE 25 Standard metric linings for LTE tunnels INTERNAL DIAMETER EXTERNAL DIAMETER TAPERED RINGS INTERNAL DIAMETER (m) (m) (m) 1.60 10.25 3 . Tapered rings are available for many of the diameters.OO 3. URS Infrastructure.79 9. sewer and outfall tunnels have been mentioned above but generally grey cast iron linings have only been used for lengths of tunnels in poor and waterbearing ground or for special sections such as chambers.13 10.80 5.46 m internal diameter. The running tunnels were 3.00 3. 04/03/2015.07 4. 20y77 .8 m. Stanton and Staveley.1 1 6. following development during the previous few years in collaboration with BRE approached the LTE with a suggestion that a short length of running tunnel should be constructed using spheroidal graphite iron and that tests be carried out by BRE to establish its performance relative t o the traditional grey iron lining.50 5. In general.50 8. In 1967.00 9. The cost of special linings is usually very high and uneconomical unless a large number of rings are required which willoffset the cost of manufacturing the pattern.75 6. Licensed copy from CIS: URS.6 Bolted spheroidal graphite iron The techniques for the manufacture of ductile or spheroidal graphite cast iron were developed in 1947 and subsequently the material has been used extensively for the manufacture of pipes.50 7. 16. Details of the lining are given in Table 2 7 and in Fig. URS Infrastructure.7 Bolted steel linings In only one recent scheme have long tunnels been constructed with bolted steel linings. 3 per cent of the diameter giving very high stresses in the lining of the order of 150 MN/m2.4 m of tunnel with an arch of radius 5. Spheroidal graphite linings are at present being used on the BR Tyne Wear Metro for tunnels over 5 t o 6 m in diameter (see Fig. Head Wrightson again proposed an alternative design in spheroidal graphite iron to the grey iron specified 150 .54 m internal diameter ~ ~ . a total of 3900 tonnes were cast (see Fig. see Fig. One ring of conventional grey iron. the outfall and inlet tunnels for the Dungeness Power Station.1 5 m internal crossover tunnel. For the Washington Metro. 60. . 1. a t ~ o u l b ~forl which A grey iron lining was specified for the Sao Paulo ~ e t r o " O and an alternative lining of bolted spheroidal graphite iron was proposed by Head Wrightson.8 m of tunnel with an arch of radius 7.These linings.Licensed copy from CIS: URS. Spheroidal graphite cast iron was also used for the lower part of the section in Bunter sandstone of the Mine Construction Consortium North York Potash deep shaft of 5.2 mm. In this scheme the linings are being used at two of the stations where there are large spans t o be supported on arches between two concrete walls. 16. were wider and had a shallower flange depth than the conventional grey iron lining and consisted of 12 segments and 1 key compared with 6 segments and 1 key in grey iron. 57). The results of this experiment showed that the material was highly suitable for tunnel segments. 58. The shape of the lining was generally similar t o the conventional grey iron lining. Following agreement on the design of the lining some 29 rings of 3. At Moorfields station 71. 56). 5 5 . with a general skin thickness of only 14.7 m and arc subtending angles between 94' and 127' has been constructed. Several widths of lining were designed and the final lining was. were very similar in form to the conventional bolted grey cast iron lining. Following the experimental length the spheroidal tunnel lining was not used in the United Kingdom until the construction of the BR Liverpool Loop Railway. In the mid 1960's Sir William Halcrow and Partners designed a steel lining for twin railway tunnels for the projected Amsterdam Metro. Changes in the horizontal and vertical diameters of the ring after building and during the driving of *kc second pilot tunnel were also measured (see chapter 7). Uncontrolled Copy. shown in Fig. however. The rings were removed when the enlargement was carried out some eight months later. This scheme was. A t Birkenhead station 34. For the construction of the Channel Tunnel Stage 2'l it was intended to use 4. one ring of the experimental lining and a second ring of the experimental lining with a 3 m m wide slot cut a t the centre bolt hole of each segment for the full depth of the flange.5 m and arc subtending angles between 100' and 110' has also been constructed.2 m wide and is shown in Fig. 04/03/2015. A stiff lining was designed t o prevent the collapse of the lining in the very weak ground which allowed an approximate distortion of 0 .86 m internal diameter and 0. were monitored with vibrating wire gauges and Demec strain gauges. especially in locations where steel segments might otherwise be used.79 m internal diameter spheroidal graphite cast iron for sections of the service tunnel a t the location of cross passages and if sections of bad ground were encountered. The lining is 1. Table 2 6 shows details of the lining. These tunnels were to pass under the River Ij in very soft Eem Clay and would be subject t o considerable loading and unloading during construction of the tunnels. The rings. The lining is remarkably thin.61 m width were used in June 1968 for the first two pilot tunnels driven for later enlargement to a 9. abandoned and only a short length of tunnel was constructed. To improve the moment of resistance there are two intermediate flanges and the tips of the circumferential flanges are returned some 7 6 m m t o prevent buckling during shoving the shield. 5 9 .0 m wide. Tapered rings were used for the horizontal and vertical curves. . Uncontrolled Copy.Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. 8 Expanded grey iron lining 16.1 1967-68 4. t o give a load of approximately 12 tonnes in the lining with the jacks operated from a single pump. 19921. The tunnel in London Clay formed part of t h e shield driven cooling water tunnels for the CEGB Belvedere generating station. In this experimental length of t u n n e l the middle two of the range of knuckle pieces were used in approximately 8 0 per cent of the length of tunnel.54 5. The ends of each of t h e segments.1 Articulated grey iron lining: In 1949 experiments were carried out directed towards the developm e n t of an expanded grey iron lining for use with a tail-less shield mainly in London Clay The conventional grey iron lining without the bolts was used but it became clear that a new type of articulated joint had to be designed t o ensure even bearing while at the same time allowing some rotation of the joints. 04/03/2015. 'A' Date External diameter m Internal diameter m Length m Cover m Ring width mm Thickness of flanges mm Thickness of skin mm Circumferential bolts Number Diameter mm Number of segments per ring 1963-64 4.1 19. The lining. Uncontrolled Copy.5 mm thick . The machining of these contact faces enabled the length of the segments t o be kept within the specified tolerances and t h e ring t o be erected undistorted and in plane. The knuckle pieces were supplied in four different thicknesses of 2 2 . In the gaps between the t w o horns forming the jacking pockets (see Fig.25 1060 15 500 20 15 16.26 810 and 220 20 to 25 610 28. URS Infrastructure. The taper packings were spot welded to the adjacent segments a t a later date.6 19. 3 2 and 36. each weighing approximately 280 kg was expanded below axis at the knees with jacks of 15 tonnes capacity with 44 mm diameter pistons. 27. alternately concave and convex t o form knuckle joints.50 4.5 mm t o allow for the different ground conditions. T h e trial demonstrated the practicability of the lining and the method of erection whilst suggesting minor improvements in the provision for handling and jacking the segments.27 800 and 200 20 to 25 507 38. In 1960-61 this form of lining was used for a section of the twin 3. except those at the jacking positions. During the next 10 years the articulated grey iron lining was evolved and the opportunity was taken in 1958 to construct an experimental length of tunnel of 20 rings of 4.27 m internal diameter. 61) of the adjacent jacking segments grey iron packing assemblies were inserted between each pair of horns consisting of one approximately semi-cylindrical knuckle piece and two 1 in 8 taper packings (see Fig.8. 61).86 m internal diameter tunnels for the experimental length of the L T E ~ 'Victoria Line.1 Feasibility Study only 5. The circumferential joints were not machined and 9. After inserting the packing assemblies the jacks were removed and the pockets subsequently filled with concrete or with a concrete block set in expanding mortar.TABLE 27 Details of bolted steel linings DUNGENESS I AMSTERDAM Licensed copy from CIS: URS. which consisted of six segments. accurately machined in parallel. were provided with semi-cylindrical bearing faces.56 4. on the Thames east of London. Licensed copy from CIS: URS. The width of the ring was. increased from 0. During the construction of the experimental length it was found that the wedges projected inside the internal diameter of the ring. URS Infrastructure. In general. 04/03/2015. The rates of progress attained for the lining were slightly higher than those for the expanded concrete lining but overall the cost per metre of tunnel was considerably higher on account of the initial costs of the segments.4 mm.5 m m which was larger than that for other forms of lining but this was possible due t o the additional clearance provided by the reduced thickness of the flanges of the lining. with its tensile characteristics. The lining was designed to be interchangeable with the 3. The maximum advance in an eight-hour shift was 1 8 rings (1 1 m). The erection tolerances specified for the lining in the experimental length were k 44. The lining took 10 to 12 minutes to erect. Several lengths were constructed using hand shields.64 tonnes which was very similar t o that of the bolted grey iron lining which was of shorter width. Details of the lining are given in Tables 28 and 29. High rates of progress were again attained using a mechanical shield.71 m conventional bolted grey iron lining. grey iron is not an ideal material for an expanded lining. after the tunnelling was completed. spheroidal graphite iron. In several instances cracks appeared in the lining near the crown which required remedial works after the tunnelling was complete and in one or two instances complete rings were replaced. The upper segments were winched into position and held temporarily o n tubular bars extended from the shield. .2 mm t o 25.5 1 m t o 0. Uncontrolled Copy. Monthly readings of the horizontal and diagonal diameters were taken. In the Victoria Line between Warren Street and Victoria the tunnels lie under exceptionally valuable property where the LondonClay is less homogeneous than usual. the results are discussed in Appendix 6. After initial troubles with the digger shield the rate of progress steadily increased t o a maximum of 230 rings (143 m) per week. creosoted softwood timber packings were inserted between the faces of adjacent rings t o distribute the pressures from the shield rams uniformly.ring was 1. Details of the lining and of the tunnels with this form of lining are given in Tables 2 8 and 29. The lining was erected in a conventional manner directly behind the tail-less shields but without the use of an erector arm.5 mm while the skin thickness was increased from 22. however. It was therefore decided t o try to reduce the number of wedges required t o be cut off for the future length of tunnels by keeping the knuckle piece at constant section by varying the thickness of the wedges t o suit the ground conditions and the variations in the size of the bead on the front of the shield. although costly. However. For the Victoria Line the lining was only altered in minor detail to improve the packing assemblies 19. The weight of the. The expanded grey iron lining was therefore used for this section whenever the ground conditions were suitable in preference to the expanded concrete or the bolted grey iron linings. should be more suitable. Although this was generally successful a small percentage of wedges had to be cut off.61 m and the depth of the flanges reduced from 127 mm to 63. During the erection of the lining with the first method described the packings were omitted at the knee joint t o enable the ring t o be assembled and the bolts fitted in the other four longitudinal joints and the circumferential bolts in the bottom two segments. Hand or mechanical shield. involved the use of a ring of ordinary segments (instead of the usual four ordinary segments. No caulking groove but lead caulking can be used.8.4 mm 6 of 4 different types (280 kg) 1.2 Expanded bolted grey iron lining: Investigations were carried out during the construction of the LTE Victoria Line t o see if the conventional bolted grey iron lining could be expanded and therefore left ungrouted for sections of running tunnels which were later to be dismantled during enlargement for other tunnels. URS Infrastructure.61 m 63. plane circumferential joints.TABLE 28 Licensed copy from CIS: URS. Details of LTE expanded grey iron lining Internal diameter Width of segment Depth of flange Thickness of flange Thickness of web Number of segments Weight of ring Iron Joints Caulking Excavation 3. two t o p segments and one key) with 38 mm thick packings in all longitudinal joints 22 (see Fig. Two methods of expansion were tried: the one. This.64 t o m e s Grey iron grade 12 Knuckle form radial joints. The ring was then jacked at the knees and pairs of folding wedges inserted at the leading and trailing edges of the joints.86 m 0.5 mm 25.9 km 30 minutes 10-1 2 minutes 142 m/week Mechanical Shield 100 m/week 30 m 3. The other method entailed 19 mm thick packings in the longitudinal joints adjacent to the key and 38 m m packings in all the other longitudinal joints. it was thought would reduce the amount of settlement at the ground surface and increase the rates of progress for the mechanical shields. In practice there was little reduction in settlement.4 km 30 minutes 7-1 2 minutes 143 m/week 40 m/week 100 m/week 32 m/week Average Mechanical Shield Hand Shield Mechanical Shield Hand Shield 16.4 mm 25. 62). 04/03/2015. Uncontrolled Copy. which was the method used. The remainder of the joint was filled with an expanding . TABLE 29 Details of LTE tunnels with expanded grey iron lining EXPERIMENTAL LENGTH VICTORIA LINE Dates Strata 1960-61 London Clay 1963-66 London Clay Maximum cover Length Average ring cycle Average building time Progress maximum Mechanical Shield 25 m 1. This again showed that grey cast iron was not a suitable material for an expanded lining. Initially this form of lining was used with hardwood packings and wedges for the pilot tunnels for the station tunnels. Licensed copy from CIS: URS. Following the use of the lining for several lengths of pilot tunnel this form of lining was used for a number of lengths of permanent tunnel when the heavier grey iron lining was desirable in preference t o the thinner special articulated grey iron lining discussed above.92 m using the same method. URS Infrastructure.71 m expanded to 3. TABLE 30 Details of expanded bolted grey iron lining Length of tunnel Depth Internal diameter Width of segment Depth of flange Thickness of flange Thickness of web Number of segments Weight of ring Iron Joints Caulking Excavation Average ring cycle Average building time Progress maximum Average Total length 1.84 m expanded to 3. 04/03/2015.51 m 127 mm 28. The estimated loadings from the footings were of the order of 390 kIV/m2. . Uncontrolled Copy. In these permanent linings steel plates and wedges of cast iron machine packings and cast iron wedges were used.92 m 0. Part of which was pilot tunnel. OXFORD CIRCUS STATION The southbound station tunnel. care had to be taken to ensure that the circumferential bolts in the invert segments were loose to avoid shearing them. Subsequently a number of rings of 3. 30 m 3. except for temporary conditions such as for pilot tunnels.2 mm 6 '0' plates t 4 No. packings and 4 No.5 m/12 hour shift 51 m/week 16.6 mm 22. In a number of instances cracks appeared in the flanges at the bolt holes and remedial measures were needed when tunnelling was complete.2 km in 6 drives. Details of the lining are given in Table 30.62 tonnes Grey iron grade 12 Plane joints Caulking grooves Hand shield and Mechanical shield 45 minutes 15-20 minutes 7.84 m and 3.mortar and the circumferential bolts in the top four segments inserted. passed only a metre or so below the third basement of Peter Robinson's store. This form of lining was also used for temporary pilot tunnels for the crossover at Heathrow Central station on the LTE Piccadilly Line Extension to Heathrow.9 Expanded steel linings Expanded flanged steel tunnel linings were used for special section on two contracts for the LTE Victoria Line 23. The details of the lining and the construction are given below. of 6. pairs of wedges 1.48 m internal diameter.84 m internal diameter were expanded to 3. Several construction methods outlined below were employed to prevent possible settlement of these footings. During the jacking of the lining. This type of situation was similar to other stations on the Victoria Line. . Details of the 6. The shield had no bead but holes were provided through the skin for injecting a lubricant if this became necessary. Fig. The taper was 2 5 mm on the diameter (see Fig. The resulting bending moment diagram contained both hogging and sagging moments of maximum value of the order of 135 kN/m and 105 kN/m respectively. a shield chamber of 7. The shield was then shoved forward and the 6. a) An expanded lining was designed to shorten the period between excavation and the lining taking a substantial part of the loading. 64). URS Infrastructure. Uncontrolled Copy. In the event the measured settlement was only of the order of 1-2 mm (see Section 19. 800 tonnes force was provided for the station tunnel and 600 tonnes for the concourse tunnels. These rams were hydraulically connected to the 24 shove rams to maintain a constant force on the face. and face rams similar t o those for Oxford Circus were provided. 04/03/2015. KING'S CROSS STATION At King's Cross Station the Victoria Line tunnels pass below the Metropolitan and Circle Line tunnels and over the Northern Line and Piccadilly Line tunnels. The upper half was designed as a semicircular two-pinned arch and analysed for five cases of loading from the footings above. c) The tunnel shield was provided with face rams with a combined total force of 800 tonnes from 12 face rams. At the end of the drive.5 mm diameter high tensile bolts provided. 63. For the construction of the tunnel the shield was designed to maintain a constant force on the face. The process was repeated until the complete shield chamber was constructed.1).48 m internal diameter lining are given in Fig.48 m internal lining erected and expanded at the rear. The expanded steel lining designed for the northbound station and the concourse tunnels had a lower half similar t o the Oxford Circus lining but with the upper half designed to withstand the large concentrated loadings applied t o the lining by the footings above. As the tunnels crossed at an oblique angle these loads could be expected at varying positions above the tunnel. The joints between the segments were designed t o maintain full continuity of section. b) The third basement was underpinned with a prestressed concrete raft in the form of a saddle over the tunnel t o spread the loads around the tunnel. 6 4 shows the congestion of tunnels in the area and the difficulties encountered when planning new underground works. Taper rings were used on the curve at the southern end of the station. t o the brick arches of the Metropolitan and Circle Line and the British Railways Midland curve was of the order of 1. The clearance from the crowns of the Victoria Line northbound station tunnel and the concourse tunnel. The segments were deepened locally at the joints and two rows of three 44.Licensed copy from CIS: URS. The excavation for a ring of the shield chamber lining was carried out in front of the shield and the lining erected.93 m internal diameter (in which to dismantle the shield) was constructed in a similar form of expanded lining. one ring in four for the northbound tunnel and each ring in the concourse tunnel. As cast iron would not be capable of taking the large jacking forces a fabricated steel lining was designed. As the shield did not cut a true circle with no overbreak through the lean concrete back filled below the saddle the lining was grouted in the crown and subsequently back grouted to fill any voids. The invert was then concreted in fondu cement to form a cradle for the shield.5 m. 04/03/2015. flyash. 16. The individual segments are lapped and bolted in the longitudinal direction t o form rings and the circumferential flanges are bolted together to give continuity in the longitudinal direction. Over one length near the Stroud end. The segments overlap and are bolted. Licensed copy from CIS: URS. Sealing strips may be used between the joints for waterproofing the lining. The liner plates are hot galvanised and used in most schemes as permanent primary linings. These systems are discussed below. was also designed with an expanded steel lining.13 m wide and 5. seepage water had affected the stability of the chalk. This short length of tunnel was hand driven and thus a smooth excavation was not possible in which to expand the lining. 7. The plates are available in thicknesses from 2. The 1390 m long Higham Tunnel. were constructed through chalk at a maximum depth of 55 m. In these 'repair' conditions the liner takes only a portion of the structural load. The segments may be erected in the crown immediately after excavation to give protection during the remainder of the excavation (see Fig. Lytag cement mix and subsequently grouted. Concrete bases were cast at either side of the tunnel and the steel lining erected to form an arch 8. Uncontrolled Copy. 16. Details of the lining are given in Table 3 1. In cases where strong alkali or acids are likely to be in contact with the sheets they may be stoved at the factory with a bitumen or epoxy coating. The liner plates are avaiiable in circular.1 mm thick. A second form of lining is available called the multi-plate lining. During steam train running a soot crust was formed over the chalk which occasionally loosens and falls due t o vibration or seepage of water.1 Arrnco liner plates25: The Armco liner plates have been used extensively in the United States and in Europe for railways.59 m high. The galvanised corrugated sheeting was 460 mm wide and 6.91 m internal diameter. The lining was erected in the conventional manner but not expanded. One third of the Higham Tunnel and two thirds of the Stroud Tunnel were lined in brick. The plates have two corrugations equivalent t o the full depth of the flanges which are between 43 and 46 mm deep. The first length was protected with a steel portal frame with steel laggings in 1971-72. horseshoe or oval shape or combination of shapes and are in three standard lengths.7 rnm to 6.HIGHAM AND STROUD TUNNELS (197 1-74) These tunnels were originally constructed in 1824 as a single canal tunnel which was later divided in two sections by a 70 m long cutting 16? The tunnels were taken over by the Southern Eastern Railway Company in 1840 and the first train ran in 1846. URS Infrastructure. and bolted together radially and longitudinally. BRITISH RAILWAYS . The void behind the lining is grouted with mortar or concrete. The remaining 32 m of tunnel was protected with a D-shaped Armco steel lining in 1972-74. The void between the lining and the excavation was then grouted and the lining expanded before the grout had set. In the United Kingdom liner plates have been used mainly for the repair of old tunnels or for secondary lining to new tunnels. and the 2090 m long Stroud Tunnel. Grout plugs are provided where required and a cement mortar grout injected t o fill the void behind the sheeting. 1034.One of the lower machine chamber tunnels. which has four corrugations and no flanges and which is usually used for the repair of old tunnels. pedestrian subways and other tunnels since the 1930's but only for a few schemes in the United Kingdom. The lining size is specified by the neutral axis diameter. 65). the remainder was unlined. . of 500 to 800 kg have occurred during the last seven years which have delayed trains. Regular inspections are carried out and soft or unstable areas of chalk are dislodged and removed. A number of these cases are discussed below. 1194 and 1353 mm and 458 mm wide. Two small rock falls.1 mm. The void between the chalk and the sheeting was backfilled with a sharp sand. the variation being due t o the differences in thickness of the metal.SOUTHERN REGION .10 Steel liner plates Two forms of liner plates are available in the United Kingdom though they have been used for only a small number of schemes.10. The plates. The joints are usually staggered from one ring to the next. The lining was designed t o be flexible t o withstand predicted subsidence. Uncontrolled Copy. The segments consist of an indented skin with flanges on all four sides which are bolted together in the longitudinal and radial directions. 66). URS Infrastructure. Subsidence due t o mining was again expected. 16. Licensed copy from CIS: URS.1) Waterproofing Bitumen gasket Neoprene gaskets up to 12 mm thick in joints.75 mm and 3.22 . of standard lengths.76 51 . STOKE-ON-TRENT .LONGTON CEMETARY SEWER RECONSTRUCTION (1967-69) This 1.HANLEY MAIN OUTFALL SEWER (1967-69) Three sections of the total 7 10 m length of this sewer were lined with Armco liner plates of 2. which were not galvanised. The plates are available to form circular.6.2 Commercial hydraulics liner plates26: The Commercial Hydraulics liner plates have been used extensively in the United States and in Europe but only in a few instances in the United Kingdom. A brick invert was constructed inside the plates t o springing level. horseshoe or oval tunnels.1 2.11 Number of bolts per segment radial circumferential 6-8 Diameter of bolts mm 5 15 .7 .5 m and 2.57 to neutral axis Commercial Hydraulics lining 1. The plates were 2. The linings are normally used as a temporary lining to support the ground for the short term conditions and subsequently lined with cast in-situ concrete. TABLE 31 Details of liner plate linings Armco lining 1.5 .0 mm and in two widths 610 mm and 460 mm.34 m diameter to the neutral axis.STOKE-ON-TRENT .19 10 .51 for 610 mm width 5% .9.6.41 Number of segments per ring 4 . The linings were originally designed for soft ground but have been used in a large variety of ground conditions and tunnelling techniques.5 mm thick 1 6 4 . were painted on site with bitumen and an internal lining of Rapid smooth bore segments erected.68 .4.20 3 4 12.37 m finished internal diameter sewer was constructed with Armco liner plates of 6. For permanent linings whlch are not encased in concrete the plates should have a protective mating.36 for 406 mm width and 1 4 . .1 mm thickness for a length of 360 m in an area where mining of the coal beneath would be carried out at a later date 164.0 Weight of segments kg 15 .5 mm to 9. 04/03/2015. are available in a range of thicknesses from 2. Curved ring Available if required Available if required. The linings are specified by external diameter (see Fig.6 3 Thickness of metal mm 2. or subdivisions.10. ~ h esheets.7 or 15.10 to external diameter Specified diameter m Width of segment mm 45 8 406 or 610 Depth of flanges mm 7 3 . were constructed in the Keuper Marl and sandstones with Dosco roadheader machines and temporarily supported with steel arches and ribs and subsequently lined with cast in-situ concrete. The use of the linings in the United Kingdom has increased during the last few years but is still o n a very small scale and in all cases the linings have been encased subsequently in concrete. In poor ground the lining can be used in conjunction with poling plates 1. Sufficient grout holes should be provided in the lining. The steel liner plates were proposed by the contractor and used in conjunction with steel arches to give a complete lining to the roof and the walls of the tunnel. URS Infrastructure. A cast in-situ concrete lining was subsequently constructed.73 m by 4. The void behind the lining may be filled with pea gravel and grouted later or grouted after erection. 3. Uncontrolled Copy.74)61 The twin horseshoe tunnels. The joints were sealed with a bitumen sealing strip. 04/03/2015. The tunnels passed below the main railway line from Bristol to Exeter in a deep cutting near the Parsons Street Station with a cover of the order of 6 m.2). .2 m internal diameter sewer passed through an area where the groundwater was highly alkaline. from the crown as soon as enough span for one plate has been excavated.55 m excavated size. The more recent schemes are briefly discussed below: WARRINGTON . A similar type of construction was used for 100 m of tunnel at the outfall end of the tunnel where there was little cover and poor ground conditions. Although there has been some instrumentation of steel liner plates in the United States little research has been done to date in the United Kingdom (see Section 19. probably from an old chemical waste tip 16'. BRISTOL-MALAGO INTERCEPTOR SCHEME (1 972. Details of the lining are shown in Table 3 1. The tunnel was lined with bolted precast concrete segments and various internal linings were considered for this particular length of tunnel. The liner plates may also be used in conjunction with steel arches when additional strength is required. but additional temporary strengthening with steel angles welded between the circumferential flanges is required t o transfer the shoving forces to the adjacent rings. in difficult ground where the crown requires immediate support. The linings can be used behind a shield.MERSEY OUTFALLS INTERCEPTING SEWER (197 1-72) A section of this 2.Licensed copy from CIS: URS.13 m external diameter liner plates 4 mm thick were used for a length approximately 160 m long. The neoprene is attached t o each of the four flanges of the segments before they are taken down the tunnel. Although the liner plates can be placed between the ribs it is usual for the ribs to be placed inside the ring of liner plates. The length of each tunnel lined in steel liner plates was 35 m. The maximum allowable deformation of the liner plate tunnels is of the order of 3 per cent of the diameter. Tunnelling caused settlement in this area. Steel liner plates were used for two short lengths of the tunnels. In compressed air or in waterbearing ground neoprene gaskets may be used which are compressed when the bolts are tightened t o give a waterproof seal.2 m to 1. Steel liner plates were chosen partly on account of the small flange thickness which did not require a reduction of the internal diameter of the tunnel. 2. The void between the outside of the lining and the excavation was filled with pea gravel and grouted later with cement grout.5 m long which are jacked forward into the face to hold the crown as the excavation proceeds. The liner plates can be erected either from the invert or. The liner plates were 4 mm thick and 10%plates formed a horseshoe to fit the excavation. There are a number of future schemes in which this form of lining may be used. The lining was erected inside the bolted lining and the void grouted with a PFA grout. passed through poor ground at a depth of some 7. .Conventional heading methods were considered but the contractor proposed laying the pipe in a tunnel lined in steel liner plates.52 m and 1. 174 m long.SOUTH SHIELDS INTERCEPTOR (1973-75) One section of this contract. and grouted. 04/03/2015.3 m external diameter liner plates 3 mm thick. Uncontrolled Copy.5 m 166.83 m external diameter liner plates of 3 mm thickness. Licensed copy from CIS: URS. URS Infrastructure.TYNESIDE SEWERAGE SCHEME . Ten drives of average length 125 rn were constructed using 1. was lined in 1. The tunnel.STONEYGATE LANE TO MULGROVE TERRACE (1974-75) On this contract approximately half the sewer was specified in heading and the contractor proposed using liner plates and encasing the pipes in concrete 66. After laying the pipe the remainder of the tunnel was filled with concrete. TYNESIDE SEWERAGE SCHEME . which was mainly in open cut with 450 mm pipes. Characteristic concrete strengths will ~ 45 ~ M N / at ~ 28 ~ days. It is then often the practice t o manufacture all segments of the specified diameter in sulphate resisting cement t o avoid confusion between the different types. following erection. The moulds were struck the next day. Precast concrete is a relatively impermeable material and.17.2. A small increase in the thickness of the lining would not generally affect the cost of the moulds for special segments and the cost of the additional concrete would be more than offset by the additional cement in the higher grade concrete and the manufacturer's inconvenience of having different concrete strengths batched by the concrete plant. The chemical attack which may occur in tunnel linings is caused either by sulphates in the ground in the vicinity of the tunnel or for sewer tunnels. the cover t o reinforcement should be 25 mm to 40 mm and dense concrete should be used. although for a small number of contracts now generally be specified at 40 M N / to ~ 2~8 days. Concrete is well suited for resisting compressive stresses but will only take small tensile stresses. any ingress of water will therefore normally be at the joints between segments or at any cracks in the concrete. Tests should be carried out on soil and water samples and the type of cement. This system was affected by the weather and was wasteful in the space required. except on occasions where the thickness of the lining is already fixed and additional hoop load capacity is required. Uncontrolled Copy. Precast concrete segments are generally cast under factory conditions either in manufacturer's precasting yards or in special casting areas on or near the site. cleaned and reassembled before repeating the process. Where linings are in a sea water environment. 17. 04/03/2015. used in accordance with Table 49 in BS Code of Practice CP1 10141. The daily production was only five segments per man. Chemical attacks on precast concrete is either by direct attack on the concrete or attack o n the reinforcement through cracks in the concrete. Precast concrete segments are generally available in ordinary Portland Cement but all manufacturers will produce segments in sulphate resisting cement when specified. Steam cured concrete has a slightly lower coefficient of permeability than dry cured concrete of the same strength. APPENDIX 4 Precast concrete tunnel linings 17.1 General Licensed copy from CIS: URS. Some manufacturers however cast all segments in sulphate resisting cement.2 Manufacture The production of concrete segments in the 1930's to the mid 1960's was generally carried out in the open air with the moulds assembled on benches which were then moved to the concrete filling point by a locomotive before returning to the bench for curing. ordinary Portland or sulphate resisting. since research for marine structures and sailing boats which have been cast or sprayed in steel fibre concrete or shotcrete has shown that little corrosion occurs in the absence of cracks. Where steel fibres are used the cover will be reduced virtually to zero. . It is a relatively brittle material which requires to be handled more carefully than cast iron t o avoid spalling of the edges or cracking. Reinforcement is often used to prevent damage during the temporary stages of handling and erecting the lining. Internal corrosion resistant linings are available as discussed in Section 15. Although theoretically these increased special segments have been cast with strengths up to 55 M N / at strengths should produce a more economical design it is not generally the case. URS Infrastructure. by aggressive agents in the liquids within the tunnel. Good quality control and adequate precautions for the curing of the concrete and the regular checking of the moulds can produce accurately cast segments of consistent concrete strength. This is discussed in Chapter 1 1. Most casting yards have special measures available to allow casting during cold weather such as steam pipes or individual canopies. . before being demoulded and removed for stacking in the open. segments have been delivered to sites within 2 8 days of casting. The process is ideally suited t o the small type of solid segment but involves high developm e n t costs t o obtain a satisfactory mix design with very precise quality control. only a very small proportion of segments are now steam cured. In the past a number of casting yards have used steam curing of the concrete which gives a strength of 7 MN/m2 after a few hours and the required concrete strength at 3 t o 7 days. say April to September. During the mid to late 1960's these production methods were greatly improved and now the majority of segments are cast under cover. The pressing of precast concrete units. Segments cast b y this method can be considerably cheaper than by conventional methods. This has been the practice on a number of occasions in the past but on a number of other occasions the segments have been rejected. for the LTE Piccadilly Line extension to ~ e a t h r o w and 17. while the larger special segments. A manufacturer will normally organise his programme t o give this minimum of 2 8 days and often has storage capacity for up t o two months production. It is not recommended that a reduction in the 28 day period is specified in contract documents.5 manufactured by John Mowlem and Co. Opinions vary on the necessity of this 28 day period. During t h e last ten years a number of manufacturers considered this process for concrete segments but only the small solid type of segments are at present suitable for this process and in addition some complications exist if there is a tongue and groove joint in the lining. if required. After casting with conventional methods. URS Infrastructure. the manufacturer is unable t o deliver segments o f the required curing duration and can show to the Engineer that the strength of the batch of concrete has already reached the required value. Dartford and Channel tunnels are always cast o n level fixed beds t o enable the tight tolerances t o be maintained. which would require a press of considerably higher capacity and also a linear production process. it is reasonable for the Engineer to accept the segments subject t o a minimum curing period of 14 days during the summer months. The moulds are moved on bogies on a closed circuit from an assembly position to the concrete filling and vibrating tables and then to the curing area. during hot weather segments can be sprayed or covered with wet hessian before demoulding.Licensed copy from CIS: URS. The larger solid segments. such as the Mersey. to be used twice daily. offsetting the high capital cost of the press. The segments were pressed with a 400 tonne press on a three position circular table at a capacity rate of 4 0 0 segments per 12-hour shift. Occasionally d u e t o production difficulties or changes in contractors' programmes. particularly when the total number of segments required t o be cast is large. In warm summer weather the strength of the concrete can reach the minimum required in 3 to 7 days while in winter it may take 14 to 21 days although the segments may be more brittle than at 2 8 days.4 MN/m2. such as paving slabs and kerbs has been carried out for a number of years.7). The larger bolted segments are still generally cast on fixed beds due t o t h e difficulty of movement of the moulds. however. due to unforeseen circumstances. However. The strength of the concrete when the segments were removed on suction pads was about 1. and 21 days during the rest of the year. When using this process the volume and consistency of concrete delivered is critical t o avoid variations in the thickness of the segment. Vibration methods have been improved in recent years and new manufacturing methods have increased the daily production rates t o 15 t o 30 segments per man thus reducing production costs and increasing utilisation of plant and space. are unlikely to be manufactured b y this method for some years. This enables the moulds.. The process has also been used for development trials of the Wedge Block h i n g . Spraying of the segments during hot weather is often carried out in the stacking yard t o help curing of the concrete.5 per cent to 2 per cent. Uncontrolled Copy. The first segments t o be manufactured using this process were (see ~ ~Sections 5. 04/03/2015. segments are removed for curing in the open air in stacking yards and generally after a minimum of 2 8 days are transported t o the site. Alternatively the moulds can be kept fixed and the concrete conveyed by mobile hopper or on travelling rails t o the moulds. T h e percentage o f segments rejected at the casting yard is probably between 0. If. delivery dates and overall weight of the moulds. Length of segment Width of segment Depth of segment Diameter of ring + 1 mm + 1 mm + 3 mm + 3 mm These are tight tolerances and should only be taken as a guide to the accuracy of the precast standard tunnel linings. were cast in steel moulds 50 . Most of the special linings are expanded or grouted unbolted linings and incorporate radial plane joints. in contrast t o the standard linings. bolted to a vibrating table. Uncontrolled Copy. concave/convex or convex/convex joints. Very accurate methods are necessary for the measuring of these surfaces. A third method which proved successful and which was used for many of the segments cast during this period used a precast concrete mould with sides and ends of timber which fitted in grooves in the base. vibration and the weather. Initially timber moulds were used.22 m to 3. During the 1939-45 war various types of moulds were considered for the bolted segments. In particular.Segments are not generally stacked in rings although on a number of contracts. In 191 1 for the construction of the 2. .9 m internal diameter subway in Croydon the segments were cast in grey cast iron moulds on a "shaking table". the segments. Only one manufacturer (Charcon Tunnels 3 1) of standard segments specifies tolerances in their brochure. although grey cast iron moulds were considered preferable on account of rigidity but were rejected on cost. High frequency electrically operated vibration tables were used. of diameter ranging from 1. Typical tolerances for the main dimensions are given below: Extrados and intrados Length of segment Circumferential surfaces k2 mm of nominal + 2 min of arc + 2 mm of nominal 17. a very high degree of accuracy is required for the convex surface forming the articulated joints. The moulds were checked daily and signs of warping and shrinkage occurred causing the joints to twist due t o the weight of concrete. with an arch base and fixed ends and loose sides. All-steel moulds consisting of steel channels and side plates with fixed steel ends but removable sides were tried but a slight twist occurred due to faulty slinging during handling. very tight and complicated due to the three-dimensional aspect.3 Moulds Little information is available on the manufacturing details of the early McAlpine lining. The steel moulds gave an excellent finish.74 m internal diameter bolted concrete lining which was originally designed for the LTE eastward extension of the Central ~ i n steel e ~moulds ~ were used. For the largest scheme in which the McAlpine lining was used. The segments were cast with the convex side upwards and the moulds were attached to high frequency vibrating tables or shock tables. These tolerances are as follows: Licensed copy from CIS: URS. There is a special need for the orientation of these cylindrical surfaces to be correct in order to avoid high local loading and thus overstressing when the lining is erected in the tunnel. The tolerances for the main dimensions of the ring are normally specified to the nominal surface profile.20 m. The specifications and tolerances for these forms of joints are individual. For the 3. the West Middlesex main drainage scheme in 1931-35. URS Infrastructure. 04/03/2015. segments have been loaded directly onto pallets at the casting yards and remained on the pallets until arrival at the face. Aluminium castings may be incorporated for flanges and bolt holes. the Fleet Line. The master base is then surrounded by a shutter and a number of die moulds cast t o suit the production programme. the concave/convex joint was reinforced (see Fig. t o take temporary stresses due to handling and erection or for the permanent load condition. the Dartford Duplication Tunnel and the Channel Tunnel Stage 2 works. and partly for handling and erection. These timber sides give fewer castings but can be renewed. while in the latter category are the McAlpine lining and the Charcon Universal lining. This is again polished and checked for accuracy. (b) external reinforcement which is used during the erection of the lining.The present standard bolted concrete linings are mainly cast from granite concrete moulds with timber sides. BOLTED CONCRETE LININGS Bolted concrete linings which are of a similar cross-section. Uncontrolled Copy. the concrete lining was designed for the Ilford extension of the LTE Central Line in 1 9 3 9 ~In~ the volume of reinforcement was equivalent to 2. 68). depending upon the diameter and the design loadings and. Steel moulds which are used for only a small quantity of bolted and smoothbore segments and for the large special segments are individually fabricated. URS Infrastructure. This master die is polished and checked for accuracy and any necessary alterations made t o the master. There is some small variation in the quantity of reinforcement per ring between manufacturers. singly or in pairs.Mott Hay and Anderson lining. One manufacturing method for the concrete moulds is outlined below and shown diagramatically o n Fig. The volume of reinforcement in bolted concrete linings is now generally between 1 and 2 per cent of the volume of the concrete. although some reinforcement may be required for the permanent ground load conditions. MERSEY KINGSWAY AND DARTFORD TUNNELS For the Mersey Kingsway tunnel18.1 per cent of the volume of concrete (see Fig. the reinforcement was partly to secure the internal steel facing plate. Details of the reinforcement in these linings is discussed in the following sub-sections. 04/03/2015. The total volume of reinforcement was approximately 0.3 per cent of . In the former category are the bolted concrete linings and the special lining for the LTE Victoria Line . This master die is then surrounded by a timber shutter and a concrete master base cast. The first bolted . the thickness of the web and the flanges. which is attached t o the segment. 17. in the case of the special bolted linings for specific contracts. the Mersey Kingsway Tunnels. t o the bolted cast iron lining require reinforcement mainly for the temporary condition of handling and erection and for the shoving of the shield. final design. and.4 Reinforcement The use of reinforcement in precast concrete tunnel linings falls into two categories: (a) Internal reinforcement cast into the segments. From a full-size drawing of the segments a timber master is made which is filled with concrete to form a concrete master die mould 28. Similar methods are used for the manufacture of the concrete vertical moulds for the solid segments. which in turn after curing are polished and assembled with the timber sides ready for production. Licensed copy from CIS: URS. although thicker. In addition. 69). 67. These are polished and then surrounded by a shutter and the requisite number of production moulds cast. fours or sixes. The outside cover to the main reinforcement is generally between 1 3 m m and 25 mm for standard linings but larger for the special thicker linings. The steel plate was attached to each of the segments above 'roadslabs' level with 12 mm diameter hooked bars at 1 3 0 rnm centres. LONDON TRANSPORT EXECUTIVE .5 Joints The types of joints commonly used have been discussed in Section 5. During the erection of the lining two semi-circular bars were inserted in the circumferential joint which increased the strength of the lining (see Fig. 71). 74). McALPINE LINING For the McAlpine Lining the segments thinner than 127 mm.7. The details of the reinforcement for the Dartford Duplication tunnel were similar. The volume of reinforcement was small and represented less than 0.6 per cent of the volume of concrete and the cover was 60 mm (see Fig. . 72). LONDON TRANSPORT EXECUTIVE . After pointing the joints the lining was grouted. were lightly reinforced for handling and erection purposes 49'50. two reinforcing stirrups of high yield steel were cast into the segments t o take these stresses (see Fig. 04/03/2015. high tensile stresses occurred near the centre of the segment.ie those for the smaller diameters. although they give increased stability of the ring if the lateral pressure on the lining is removed or reduced at some later stage as in the case of a subsequent excavation close t o the tunnel.1 per cent of the volume of the concrete (see Fig. The segments were reinforced for handling and erection and for the concave/convex joint detail. URS Infrastructure. and it was found that. The diameters of the bars varied with the diameter of the lining from 15 mm to 28. For lengths of tunnel at depths in excess of 2 0 m. The volume of reinforcement was 1. The cover to the reinforcement was 37 mm. CHARCON UNIVERSAL LINING In the Charcon Universal Lining two hoop bars are inserted through sleeves cast in the segments and coupled together at each of the segment joints in the ring47 (see Fig. The outside cover to the reinforcement was 38 mm while that in the concave joint was 25 mm.FLEET LINE The lining for the Fleet Line is discussed in Section 17. MOTT HAY AND ANDERSON LINING Licensed copy from CIS: URS. CHANNEL TUNNEL STAGE 2 .9 per cent of the concrete volume and the cover was 2 0 mm. The bars act mainly as temporary supports during the erection of the ring. Complete grouting of the bars within the segments may not always occur. Uncontrolled Copy.the volume of the concrete. with the small circumferential length of the segment. The volume of reinforcement was a little over 0.SERVICE TUNNEL The lining for the Stage 2 works for the Channel Tunnel service tunnel consisted of five segments and a key in the crown. 5. ' ~ reinforced in the concave part of the The Mott Hay and Anderson Lining for the Victoria ~ i n e was concave/convex joint and in the vicinity of the jacking points. 17. which gives a point load contact.5 mm. 73).VICTORIA LINE. 70).3 and Table 32 below gives details of the individual joints for concrete linings illustrated in Fig. Tests were carried out on the double convex joint. EXPANDED LININGS GROUTED SMOOTH BORE LININGS Mc Alpine Tongue and groove Spun Concrete Flexilok Concave/convex Rubberised bituminous reinforced strip in both joints S p u n Concrete Extraflex Plane joint with nylon dowels Rubberised bituminous reinforced strip in radial joint. 04/03/2015.TABLE 32 Details of joints in precast concrete linings Type of Lining Circumferential Joint I Remarks Plane Bituminous felt in radial joints Don-Seg Plane Bituminous paint on radial joints Wedge Block Plane Rubber Bitumen emulsion on radial joints BR Greenwood t o Potters Bar Tongue and groove Bituminous paint on radial joints LTE Victoria Line Experimental length Stepped Bituminous paint on radial joints Halcrow Lining Stepped Bituminous paint on radial joints Mott Hay and Anderson Lining Plane Bituminous paint on radial joints Fleet Line Plane Wedge only painted with bituminous paint Piccadilly Line Extension Plane Wedge only painted with bituminous paint BAA Heathrow Cargo Tunnel Plane Bituminous paint on middle third of radial joints BOLTED LININGS Licensed copy from CIS: URS. Charcon Tongue and groove Tongue and groove Rapid Universal Mersey Kingsway Plane - . Cellular rubber strip with neoprene cover in circumferential joint. URS Infrastructure. Uncontrolled Copy. Three of the rings were tested in conjunction with three cast iron rings in a trial tunnel with 0. The circumferential flanges were increased in thickness to 102 mm with four 9. The number of bolt holes was reduced from 52 to 3 1 and the solid key replaced by .5 mm with the flanges and the central circumferential rib 76.5 mm diameter bars (see Fig. 75). The lining was then redesigned to provide greater strength in the longitudinal direction. This lining was designed to be used for sections of the LTE running tunnels in London Clay. Exhaustive tests were carried out on the prototype lining and the future modified linings. using timber moulds. To strengthen the bolt holes mild steel ferrules were cast into the segments to form the holes. Uncontrolled Copy. instead of the cast iron linings which were in short supply on account of the rearmament programme.66 m internal diameter rings were cast. 68).TABLE 32 (Contd) Type of Lining Radial Joint Circumferential Joint Dartford Duplication Concave/convex Radius 534 mm and 814 mm Plane Rees Mini Concave/convex Concave/convex Concave/convex Radius 2400 mm Plane Remarks - Uncured rubber strip in both joints Licensed copy from CIS: URS. The longitudinal stiffeners which tapered from 50. 04/03/2015. One ring of the lining was then tested behind a shield in one of the running tunnels which was under construction. while the radial joints had two bolts.44 m concrete and cast iron linings which gave similar results.5 mm diameter reinforcing bars and the central rib omitted. Similar tests were carried out with three rings of 2.5 mm diameter bars. The locations of the circumferential bolts were similar to those for the cast iron lining with the exception of the crown bolt which was omitted due to the solid key. In the first design the skin thickness was 44. In the latter case'the concrete lining regained its shape after the removal of the load.76 m cover. A small number of 3.6 Bolted and dowelled concrete linings In 1937 investigations were started into the design of a precast reinforced concrete lining of a similar form to the traditional cast iron lining which lead in turn to the present generation of bolted concrete linings 29.6. two top segments and one key.5 mm diameter bars. To produce high shove pressures the excavation was not trimmed to the cutting edge of the shield and a total thrust of approximately 450 tonnes was'applied t o the lining at which thrust the lining failed badly.8 mm thick while the number of reinforcing bars in the radial flanges was reduced to two (see Fig.Central Line extension: The design of the lining29 was generally similar to the cast iron lining with four ordinary segments. while the radial flanges were reinforced with three 9. In the first design the two types of linings had the same internal and external diameters and ring width to enable the linings to be interchanged. EXPANDED GROUTED LININGS Channel Tunnel Stage 2 - 17. The skin was increased to 50. 17. The ground surface was loaded to approximately 190 kN/m2 at which stage both linings had squatted some 25 mm and two of the cast iron rings had cracked in the crown while only one fine crack was apparent in the three concrete rings.3 mm were reinforced with two 9.2 mm thick. URS Infrastructure. The circumferential flanges and central rib were reinforced with two 9.1 LTE .8 mm to 114. 07 m internal diameter. Creosoted wood packings were used in the circumferential joints. Additional care was required for stacking.03 m internal diameter rings bolted together with packings in the joints t o give 5. .3 (1) For the LTE tunnels. the remainder being in bolted concrete segments. Cast iron linings were used for approximately one-third of the total length of these shelters to obtain an earlier starting date for t h e construction. two of which are described below: 17. on average. TABLE 33 Details of bolted concrete lining for LTE Central Line extension to Ilford and for London air raid shelters 1 Internal diameter Width of segment Thickness of flange Weight of ring tonnes Number of segments m m mm tonnes Moulds Minimum concrete strength MN/m2 Total length of Tunnels km ~oints Notes: LTE Central Line 1'K' Steel 41. (2) For the air raid shelter tunnels.4 4. The internal diameter of the final lining used in the scheme was increased t o 3.03 m internal diameter tunnels 430 m long.a longer flanged key.44 6'0' 2 'T' 1 'K' See Section 17. This lining was similarly tested behind the shield with satisfactory results. with the exception of the key had grout holes and the rings were grouted with ordinary Portland cement. Details of the lining are given in Table 33.5 1 152 2. 04/03/2015. Details of the lining and the tunnel are given in Table 33.2 Deep tunnel air raid shelters in London: In the early years of the war eight deep tunnel air raid shelters were constructed in London.4 plane(1) Air raid shelters 5. two rings per eight-hour shift were built. A 2 5 mm skin was attached t o the outside circumference. URS Infrastructure. The linings were further developed during the early years of the war. and with the use of a shield four rings per eight-hour shift were built. made up of four 5. creosoted wood packings similar to the circumferential joints were later used.03 0. except in one contract in which a rudimentary shield was fabricated o n site. which were very expensive. Although there was n o dangerous concentration of sulphates in the clay the backs of the segments were heavily coated with bituminous emulsion. All segments. During the war linings t o t h e same basic design were used in a number of schemes. Without the use of this shield.74 m to accommodate the signalling equipment etc.3 2. handling and erecting the segments and no more damage occurred than t o cast iron segments. four t o the north of the Thames and four t o the south. These shelters and associated tunnels were adjacent t o existing London Transport Stations and were designed for possible connection into t h e system. Each of the shelters consisted of twin 5.6. 3 m m bituminous packings with a matrix of hessian were inserted in the radial joints. Licensed copy from CIS: URS. 3 mm bituminous packings were initially inserted in the joints but as these tended t o flow under pressure. The rings took approximately 20 minutes to erect. The linings were inspected in 1974 and n o deterioration was apparent. The tunnels were constructed by hand excavation without a shield. were omitted and the haunches at the ends of the segments were removed. Uncontrolled Copy. The mild steel ferrules. which would otherwise have obstructed the structure gauge. A number of other manufacturers will produce segments for specific contracts but d o not manufacture a standard range. (See note). It was found that some 2 1 days after grouting the bituminous packings started to flow due to the build up of load on the lining. For the 2. now Charcon Tunnels Ltd. 04/03/2015.6. The standard range of diameters now available is manufactured by three main firms:31 C V Buchan (Concrete) Ltd. The extent of their use is discussed in Sections 3.57 m have no standard increments but were originally cast for specific contracts.44 m and 3.57 m but some intermediate diameters are available.Dorset coast: A series of tunnels27 were constructed at depths of 35 t o 40 m in the Kimmeridge Clays on the Dorset coast of 2. Licensed copy from CIS: URS. TABLE 34 Details of standard bolted concrete linings - Internal Diameter Width of Segments Thickness of Segments Weight of Segments Number of Segments 1.03 m segments.4. 152 mm increments generally up t o 3. a travelling erector was designed from a semi-circular ladder with revolving steel tube treads and with a small air hoist. calculations should be made for depths below 25 m to verify their suitability (see Fig. and similar segments were cast by a number of other precast concrete manufacturers. The segments.4 Standard bolted concrete linings: A standard range of bolted concrete linings was introduced after the war by Kinnear Moodie Ltd. 310 kg. 17. The squeezing of the packings sealed many of the joints between the segments which had previously developed leaks.74 m and 5. the 5.44 m and 3. cast in moulds with concrete bases and timber ends and sides. Uncontrolled Copy. 76). The segments after demoulding were immersed in water for a period of 48 hours.7 m although diameters up to 38.03 m diameter tunnel was constructed full face.1 m have been manufactured for shafts and tunnels.52 m to 10. For the 5. Charcon Tunnels Ltd (formerly Kinnear Moodie Concrete Ltd) and Costain Concrete Ltd. The diameters above 4.03 m tunnel 6 mm thick creosote wood packings were used in the radial joints instead of the bituminous packings. URS Infrastructure. The linings for the 2. and the additional height of the stage. 3. After a further three t o four days no additional movement occurred. .44 m diameter pilot. These linings have been used in many hundreds of kilometres of tunnels in all types of strata.44 m.3 Defence installation .2 and 5.03 m internal diameter in bolted concrete linings. but due t o the weight of the 5.17. were in high alumina cement due to possible attacks from the sulphur compounds in the Kimmeridge Clays.74 m tunnels were erected by hand. Details of the linings are given in Table 34.6.74 m tunnels bituminous packings were used in the radial joints and 25 mm diameter tarred hemp rope in the circumferential joints. Taper rings or solid tapered packings for curves are available. The linings are generally suitable for tunnels up to 30 m depth but as this depends on the ground conditions.05 m and 254 mm increments to 4. With the exception of a short length of 2. The segments were rolled by two bolt holes per ring. a hole was drilled in these segments. As the key segment had no grout hole. but mainly in soft ground and soft rock tunnels. After every third ring had been erected the joints were pointed with cement mortar and then grouted with high alumina cement when the mortar was set. A number of these linings are detailed in Table 35. Uncontrolled Copy. 3 mm thick bituminous felt in radial joint. o r other tunnels requiring a smooth bore. TABLE 35 Details of tunnels with special bolted concrete linings - Thames Cable Tunnel 1967-1969 Date Severn Cable Tunnel 1969-1972 External diameter m 3. Bolts in radial and circumferential joints used t o support segments.TABLE 34 (Contd) Moulds (a) (b) (c) Concrete moulds with timber or steel sides Aluminium moulds with timber sides Steel moulds Licensed copy from CIS: URS. During the last few years the diameters in the range 4 to 6 m have been used more often but mainly for tunnels in soft or medium rock.2.5 37. Erection No erector arms or former ring required for small diameter tunnels.3 m diameter.08 3. The standard linings have been used since their introduction mainly for small diameter tunnels.40 3.40 Internal diameter m 3. URS Infrastructure. up to 4 m. Note: The number of diameters in the range is likely to be reduced to conform with recommendations in the recently published CIRIA Report No. This is more critical for the larger diameter tunnels where the ram pressures may be larger and therefore special bolted concrete rings are often cast for these projects designed t o suit the individual requirements. The secondary linings available are discussed in Section 15.5 6 + Key 6 + Key Number of segments For water or sewer tunnels. 66. 04/03/2015. leading t o difficulties in waterproofing. SOLID INVERT BOLTED CONCRETE LININGS C V Buchan (Concrete) Ltd have recently introduced an alternative design for the bolted lining with a solid invert with locating dowels and sockets for the interlock between rings.4 M N / ~ ' to 45 MN/m2. with a few short lengths of 4 t o 5. When bolted linings are used in shield driven tunnels fractures or excessive shove pressures may cause damage t o the skin of the lining. Ordinary Portland cement or sulphate resisting cement. The larger diameters have usually been used for shafts. For a ring with an odd number of ordinary .08 Length m 1586 3680 Cover m 40 45 Ring width mm 7 62 7 62 Thickness of skin mm 37. a secondary lining is necessary. Caulking grooves Cast in both radial and circumferential joints. Joints All plane. All segments cast horizontally Average concrete strength 41. . except for caulking if necessary. is erected with alternate segments ( 1 . 8 and 10) approximately 100 mm forward of the last ring erected to allow sufficient space for the last segment (6) to be placed in position. since no spaces require to be filled. Increased labour and handling charges may make this feature more significant in the future. URS Infrastructure. In the Post Office Waterloo contract a special length of 20 rings was cast with semi-circular grooves on all joints which formed a continuous circular duct.6 mm greater than the excavated diameter.6 mm smaller than the excavated diameter. 6 . In addition little damage is likely to occur.7 Expanded concrete linings Licensed copy from CIS: URS. Details of the types of expanded concrete linings used in the United Kingdom are outlined below with details of the tunnels constructed: 17. When building the ring. when the shield is corrected for level (see Fig. This duct was subsequently injected with a mixture of bentonite and cement which formed an effective waterproofing barrier. 17. however.5 MN/rn2 and 14 M N / ~ ~ . These infill segments reduce the time and therefore the cost of clearing out the tunnel at the end of the drive.1 Don-Seg lining: The Don-Seg lining was first used for an experimental tunnel for the Metropolitan ~ has subsequently been used in four schemes as Water Board's Thames-Lee Valley tunnel in 1 9 5 0 . 7 and 9) with the wide end adjacent to the last erected ring and the remainder ( 2 . 04/03/2015. 8 and 10 to close the ring varied from contract t o contract but in the Thames-Lee Valley tunnel one of the lower segments (2 or 10) was usually shoved last. 3 . From the manufacturer's point of view. Uncontrolled Copy. Average rates of progress of 46 m per week were obtained on several contracts for hand sheld drives and 63 m for partial or full face machine drives with maximum rates of 55 m and 110 m respectively. The lining. 4 . care must be taken to ensure that the circumferential face is plane and that all segments are properly aligned and in contact before the last segment is shoved. In the experimental tunnel the segments for the first 39 rings were cast with a theoretical diameter 1. an attractive feature of the DonSeg lining lies in the single type of segment. 77). In the Thames-Lee Valley tunnel the specified minimum and maximum ram pressures were 3. When the lining is erected the tunnel is complete. thus the storage of moulds and segments is simplified.5 1 ~and detailed (see Table 36). In order to overcome variations in ram pressures due to changes in the properties of the clay it is necessary to change the relative diameter of the tunnel excavated by the shield and the external diameter of the lining. 5 . 6 . The remainder of the rings were therefore cast with the theoretical diameter 1. The total length constructed is approximately 30 km. It was found that these formed a ring which was too large for the excavation and was difficult to close.4 MN/rn2 to 25 MN/m2 (equivalent to a force of up to 60 tonnes) in the experimental and the Ashford Common tunnels. varied from 1. 78. This may be done by either changing the thickness of the bead with a clip-on adjustable bead on the cutting edge of the shield or by using a closing segment (6) of shorter or longer circumferential length. The segments have to be accurately cast on account of the twist in the joint faces to avoid damage when the alternate segments are shoved.segments the invert segment and the bottom one or two pans of the two adjacent segments are cast solid while for a ring with an even number of segments the bottom two pans of each of the two invert segments are solid. In one contract all the ordinary segments were solid. The ram pressures required to close the ring. which is essential for all the joints to fit due to the taper of the segments. The sequence of shoving segments 2 .7. which is shown in Fig. 4 . due to excessive ram pressures in the invert. 53 m 0.51 m 0.70 above 2. URS Infrastructure.29 m 2. TABLE 36 Details of tunnels with Don-Seg linings - POST OFFICE METROPOLITAN WATER BOARD Tharnes-Lee Experimental Tunnel MINISTRY OF DEFENCE Waterloo (cable) Thames Lee Ashford Common -- Date 1950-5 1 1952 1955-59 1969 1970-72 Internal Diameter 2.63 below 44 m 2.6 rn 0. Caulking Moulds 470 rn - Radial joints coated with bitumen Joints Taper - 1 in 10 1 in 10 No groove No groove Concrete moulds outside face uppermost 1 in 10 Short section only with groove Caulking groove Concrete moulds cast vertically - .29 m 1.53 m 0.53 m 2.Licensed copy from CIS: URS. Uncontrolled Copy. 04/03/2015.37 rn Depth 32 m 27 m 20-58 m 26-46 ni Length 300 ni 570 m 27 km 1.5 krn Number of Segnients 10 10 12 10 Width of Segment 0.3 m Thickness 151 mm 152 rnm 190 rnm below 44 rn 152 rnrn above 150 mm 124 rnm 1 in 10 1 in 10 . each of the other longitudinal joints being parallel t o the centreline.A modified Don-Seg lining has been used in Belgium on five schemes under the River Scheldt at Antwerp since the mid 1960's. 17. In addition the lining has been used for five schemes under licence to the Board for a total length of approximately 4 5 km giving a total length constructed of approximately 95 km (see Tables 37 and 38). taking an average of some four minutes. Uncontrolled Copy. The introduction of the Don-Seg lining was a major development in the methods of lining tunnels in stiff cohesive soils which led in turn to other similar forms of lining and a considerable increase in the rate of driving tunnels. however. The longitudinal joints are painted with three coats of a paste formed with rubber bitumen emulsion. The lining has been used in London.7. some sections of which have been of very stiff material with bands of rock or claystones and others of very soft material. A key of smaller circumferential length was provided t o reduce the weight for handling purposes. In one recent contract special key segments were required of standard width but with variations in the circumferential length of +15 mm. while the longitudinal joints of the wedged shaped key which were originally parallel are now radial. To close the ring some movement of these segments is essential although. 04/03/2015. Subsequently. . it is unlikely that much friction will have built up. the The lining was first used for an experimental length of the Thames-Lee Valley tunnel in 1 9 5 5 ~ For main tunnel the lining was specified as the alternative to the Don-Seg but in all contracts the successful contractor preferred to use the Don-Seg lining. In the original design the key segment was 25 mm less in width than the adjacent segments but this has been increased t o 5 0 mm t o give more latitude in stressing the ring. with four face workers but without a shield erector arm. as there is little load in the ring until the last segment is closed. the Don-Seg lining has been seldom used and has probably been underrated. The internal diameter is 3. All segments are placed directly against the clay and there is little movement during the closure of the ring.8 M N / ~ ' for the closing of the ring and this figure is normally attained. Portland cement and water to improve the stress distribution and t o seal the joint. the Wedge Block lining has been used wherever possible in all the Board's tunnelling schemes. The record progress rate for a mechanical digger shield is just over 300 m per five-day week and 435 m per seven-day week. The Wedge Block lining41 has avoided this movement b y having a single tapered key in the crown.2 Wedge Block lining: The Wedge Block lining was developed from the Don-Seg lining by t h e MWB ~ l 1952. The lining is quick to erect. Following the introduction of the Wedge Block lining by the Metropolitan Water Board. Lias and Gault clays. +10 mm. 79). ~ . -15 mm and -25 mm to allow for variation in the ground conditions (see Fig. URS Infrastructure.5 m internal diameter lining for both hand and mechanical shields.2 km. Outstanding rates of progress have been attained with the 2. Caulking grooves are only cast on the circumferential joints. The total length constructed for the Board is 50. The key is inserted longitudinally from within the shield requiring a special recess in the shield. The specified ram pressure is usually 13. In the Don-Seg lining alternate segments following the construction of the Ashford Common ~ u n n e l in are forward of the last ring erected so that the closing segment can be inserted. Licensed copy from CIS: URS.53 m and 12 segments form the ring. 04/03/2015.3 km 86. Details of Wedge Block lining Internal diameter 2. Segments cast vertically.54 m 2. Average ring cycle time Digger Shield 10.73 m Length constructed 5. Portland cement and water. Uncontrolled Copy.TABLE 37 Licensed copy from CIS: URS.12 minutes Hand Shield 1 hour Building time Average 4 minutes Jacking load Up t o 4 0 tonnes into the ring .7 km 0. URS Infrastructure. Caulking Caulking grooves cast in segments when required in circumferential joint.03 m 2.6 m until 1960 0. Joints Plane radial joints painted with 3 coats of a paste formed with rubber bitumen emulsion.9 km Number of segments per ring 10 12 12 Weight of segment 128 kg 178 kg 226 kg 192 kg Thickness of segment 128 mm 140 mm (Depth 45-60 m) 178 mm (Depth > 60 m) 140 mm Width of segment 0.686 m since 1960 Moulds Concrete moulds. 04/03/2015. Dia.TABLE 38 List of tunnels with Wedge Block lining METHOD O F EXCAVATION Date I Strata Int. Empingham Reservoir Tunnel (Water) 1972-74 MS Lias Isle of Grain CEGB (Cable) 1973-75 Total length Note: HS MS BS Hand shield Mechanical shield Boom Cutter in shield . Maximum Cover Length Licensed copy from CIS: URS. krn Thames-Lee37 1955 HS London Clay Walton 1957-59 HS London Clay Staines Bypass 1959-60 HS London Clay Staines Kempton 1960-63 MS London Clay Coppermills 1966-68 HS MS London Clay Datchet to Wraysbury 1967-69 HS MS BS London Clay Sunbury Cross 1967-68 HS London Clay Coppermills 1969-70 HS London Clay MS London Clay Southern Tunnel (Ashford to Merton) 0.88 I Total length SCHEMES UNDER LICENCE TO MWB Ely-Ouse Tunnel (Water) 1968-71 MS Gault Clay Three Valleys Tunnel (Water) 1971-72 MS London Clay Prittle Brook (River Division) 1972-73 MS London Clay Nene and Welland. URS Infrastructure. Uncontrolled Copy. . The remaining jacking space was then filled with dry pack concrete t o complete the ring.The tunnels are parallel to the existing main line tunnels at a distance between centrelines of 15 m (see Fig. In practice only part of this tolerance was taken up in building the rings. this would have required additional moulds. The design of these refuges.7. thicker than would be used today for a similar tunnel but this was the first large diameter tunnel constructed in expanded linings prior t o the advances in technology during the last two decades.17. 0. however. The linings were. In the precasting factories. irregularities in the tunnel internal profile and would have affected the rates of construction of the tunnels. were provided in the tunnel at 20 m centres on each side of the tunnel. The stresses in the lining were designed generally t o be a maximum of 7 M N / ~ 'and 14 M N / ~ 'at the joints. of total length 1.3 Greenwood to Potters Bar Tunnels: Three tunnels. Supersulphated cement was specified to avoid possible attack by sulphuric acid from the steam engines using the tunnels and other gases emitted from diesel engines when they replaced the steam engines. the jacks were removed after a minimum of 2 4 hours in a continuous cycle. The tunnels. with an average rate of progress of three rings per eight-hour shift. two openings were constructed for passages t o ventilation shafts in the long tunnel. Details of the lining and tunnels are given in Table 39. Ten pairs of jacks were used and.9 m wide. of internal diameter 8. The rings were expanded with 20 tonne jacks positioned at axis level of the tunnel and the space between the horns of the adjacent jacking segments was filled with dry pack concrete (see Fig. The 15 ordinary segments subtend each a nominal 14' arc. Cast iron linings were used for short lengths at each of the six portals where there was reduced cover. Four separate linings have been designed and used in these schemes l9>*l. thickness of biturnastic paint and possible dirt in the joints.4 LTE running tunnels: The first expanded concrete tunnel lining used in the LTE running tunnels was in the experimental length for the Victoria Line in 1960-61. were the first large diameter tunnels to be constructed with an expanded lining. URS Infrastructure. 80).08 m . two short and one long. The reinforced invert blocks were manufactured at one of two precasting factories on the site in rapidhardening Portland cement and the other unreinforced segments at the second factory in metallurgical supersulphated cement imported from Belgium.1' which was the calculated possible overall increase in circumferated length of the ring allowing for the cumulative effect of plus tolerances. Although standard rings could have been designed thinner than the special rings adjacent t o openings. Subsequently this form of lining has been used for sections of the Victoria Line (1963-69) and the Fleet Line and Piccadilly Line extension to Heathrow (1972-74). The rates of progress attained with these linings are discussed in Section 10.1. 04/03/2015. 17. were constructed for this scheme in 1955-59 for British Railways Eastern Region 35 .7. 80). required the load in the rings incorporating the refuge to be transferred to the two rings o n each side of the refuge through concrete shear pins and post tensioned bars. Uncontrolled Copy. but the moulds for these segments were reduced in arc by approximately 0. A two man gang was employed on each shift carrying out this concrete filling work. Details of the linings are tabulated at the end of this sub-section (see Table 40). steel moulds were provided for a rate of production of 10 rings per day. Six special rings were therefore required for each refuge with sixteen standard rings between refuges.67 km Licensed copy from CIS: URS. In addition. The total length constructed using these linings is some 26 km. Staggered refuges. 76 m3/man hour Excavation Hand shield and clay spades . Uncontrolled Copy.46 m Moulds Cast aluminium and steel moulds. 800 uses. Joints 75 mm tongue and groove radial and circumferential joints coated with bituminous paint. All other blocks .75 tonnes 15 MK 1 14' 3. 32 C. URS Infrastructure.Metallurgical Supersulphated cement. 16 C.75 tonnes 4 MK 3 16' Jacking space 2 x 1%' Thickness of block 0. 04/03/2015.l rings) Potters Bar 1110 m (incl. 10 rings of moulds.l rings) Number of blocks 0. Segments cast on the site on their sides.08 m Cover 3-27. Concrete Invert block .l rings) Hadley North 3 12 m (incl.685 m Width of block 0.5 m Length Hadley South 351 m (incl. Caulking No caulking groove Average ring cycle time 2 hours Average building time 50-60 minutes concurrent with excavation Progress Maximum sustained 29 m/week.Reinforced concrete with Rapid Hardening cement.TABLE 39 Greenwood to Potters Bar tunnels DETAILS OF LINING Licensed copy from CIS: URS. 2 1 C.5 tonnes 1 MK 2 83' 0. 3 rings18 hour shift Average 18 mlweek 16 men in face Excavation rate 0. Dates Strata London Clay Internal diameter 8. A shorter circumferential length of block was used for the first few rings after the weekend and in a few areas of soft clay. The expanding of b o t h rings was below axis. at the knee joint. . the convex/convex joint was introduced into the Halcrow lining. During the experimental length of tunnel it was seen that during erection the segments did not centre themselves. and that these slight inaccuracies of erection caused large eccentricities in the line of contact in the joints of the completed rings. For the experimental length of the Victoria ine el^?^' a new type of radial joint was designed with concave and convex faces t o reduce the bending moment in the segments and spalling at the edges of the segments. The ends o f the frame sat in pockets cast into the face of the segments. but the contractor proposed a n alternative method of expanding the ring using a pair of reinforced concrete folding wedges.000 were seriously damaged. This latter method was employed and the second wedge was driven home with a special ram to 10 tonnes producing an expanding force of 2 5 tonnes. The ring was designed to be jacked in the crown. The range of concrete blocks varied in increments of 1. The space between the two jacking segments. Both t h e Halcrow and the Mott Hay and Anderson linings had a length t o thickness ratio of 7. 83) to transfer the jacking loads t o the two jacked segments. A selection of packers was provided of varying circumferential length as in the Halcrow lining. which was the first time this type of joint had been used. 04/03/2015. Concrete blocks were also used to fill in the jacking pockets. 81).2 which was a little high a n d some damage occurred to the segments during handling and after erection due to excessive ram forces from the digger shields. In the Mott Hay and Anderson lining the joints were concave/convex with a small cage of reinforcement provided in t h e concave joint t o prevent spalling. described in Section 16. The circumferential joints were stepped b y 38 mm.5 mm in thickness. These linings incorporated similar lengths of segments including two special invert blocks b u t had different jointing and jacking details (see Figs. after stressing. was filled with a concrete block to a close fit. As in all expanded linings. if the circumferential face was out of plane there was a tendency t o crack a segment when t h e shove rams were applied. even w i t h the application of friction reducing bitumen paint. 82 and 70). it was necessary to shave off a thin layer of clay before erecting the lining. b u t generally only t w o or three different blocks were required at the face.8 where jacks were inserted to expand the ring and cast iron knuckles with concrete packers inserted between the horns on either side of the jacks. the one by Sir William Halcrow and Partners and the other b y M o t t Hay and Anderson 19. It was found possible t o predetermine the width of wedges to enable full length wedges to be driven. In practice some small reduction of the load in the ring took place following the jacking with both these systems. The m e t h o d of expanding the Mott Hay and Anderson lining was similar t o that used for the expanded cast iron lining. remedial measures were required to protect the reinforcement. If spalling did occur. To avoid this and possible spalling. Uncontrolled Copy. A short experimental length with a lining 1 1 4 mm thick showed that a thinner lining could be used (see Fig. Some minor spalling of the segments occurred but only 10 our of 33.EXPERIMENTAL LENGTH O F VICTORIA LINE Licensed copy from CIS: URS. In the Halcrow lining a special jacking frame was designed (see Fig. VICTORIA LINE For t h e Victoria Line two concrete linings were designed. with 2 0 tonne jacks. URS Infrastructure. 6 km (used in Piccadilly Line Ext) Number of segments 14 t 1 pair of reinforced wedges 11 t 2 blocks 12 t 2 knuckle pieces and packers 20 t 2 wedges blocks Width of segment 0.4 km 6.6 m 0.46 km (incl. Line Joint Concave/ convex Convex/ convex Concave/ convex 102 mm Radius Convex/ convex Radius 19000 mm Fleet Line 11250 mm Picc. URS Infrastructure.03 m (trial length) Depth - 20-40 m 20-40 m Length 1.6 m 0.6 m 0. 04/03/2015.81 m Halcrow lining Mott Hay and Anderson lining FLEET LINE/ PICCADILLY LINE EXTENSION Halcrow lining 4.3 km plus 0. Uncontrolled Copy TABLE 40 Details of expanded linings for LTE running tunnels LONDON TRANSPORT EXECUTIVE RUNNING TUNNELS VICTORIA LINE Experimental length lining Date 1960-61 Internal Diameter 3.Licensed copy from CIS: URS. 30 m trial length) 11.6 m Thickness of segment 229 mm 114 mm (trial length) 152 mm 152 mm 168 mm Fleet Line 152 mm Picc. Line Caulking Moulds Joints caulked where necessary Steel moulds Steel moulds Steel moulds Fleet Line . Line .Pressed segments in steel moulds .Concrete moulds Picc. An erector arm was provided.7. as for the Victoria Line linings but with tapered wedges 1 0 0 m m narrower than the standard ring (see Fig.3. which were originally cast for the Brixton section o f the Victoria Line. Precautions described in Section 7. The existence of 22 point loads requires additional care during the erection t o build the rings true. The invert segments.000 segments cast only 139 or approximately 0. The time taken to erect and expand the ring was approximately 3 0 minutes. reinforcement was provided at the centre of the segments.29 m. FLEET LINE AND PICCADILLY LINE EXTENSION Licensed copy from CIS: URS.Subsequently. T h e tunnel passes below one of the two main runways at Heathrow Airport at a minimum depth of 7. Twelve pairs of jacks were used. T h e dry pack concrete was mixed and placed by one man working on the day shift. The new features o f the lining have reduced the amount of damage to the segment. thus giving a nominal point load o n the segment t o avoid loading near any edge. F o r rings a t depths of more than 20 m.1 tonnes. A number of segments received superficial damage during handling and erecting.5 per cent were damaged or broken. The space between the horns of the jacking segments was filled with dry pack concrete (see Fig. Adjustment in the roll of the t o p half of the ring was carried o u t . For the Fleet Line and the Piccadilly Line Extension to ~ e a t h r o w a new ~ ~ lining was designed t o try to reduce the damage during handling. When rings are out of plane and the point loads between segments move a few centimetres from the centre of the joint. 85). to enable the t o p half of the ring t o be erected only five minutes after the shove rams in t h e t o p half of t h e shield had been retracted. had the largest percentage of breakages at 2. was constructed in 1966-68 for t h e BAA and is the largest diameter tunnel lined with an expanded lining43. These segments were loaded on to the lowered erector arm during the excavation for the ring. fitted with vertical and inclined rams. a t the knees. 04/03/2015. which weighed 1. were hand picked from a large stock pile in one of the Board's Depots. 84). T h e longitudinal joint was convex/convex but in addition was convex/convex in the longitudinal direction. of internal diameter 10. URS Infrastructure.4 per cent. These rings built well. Uncontrolled Copy. The rings were cast in steel moulds in a casting yard o n the site (see Table 41).3 had t o be taken t o limit surface settlement. equivalent t o a progress of three t o four rings for each shift of eight hours. When the jacks were removed after 2 4 hours the remaining space was filled with dry pack concrete to complete the ring. The ring was expanded b y jacks positioned at axis level with a load of 25 tonnes. The circumferential joint was plane. 17. after the first 25 per cent of the load had been applied by increasing the load in the appropriate jack first. erecting and shoving of the shield. equivalent to four rings plus 12 ordinary segments. there is a slight tendency for minor tension cracks t o occur a t the ends of the segments during shoving for subsequent rings.5 Heathrow Cargo Tunnel: The Heathrow Cargo Tunnel. The ring of 20 segments and two wedge keys was expanded with a load of 2 0 tonnes in a similar position. A total of approximately 2 4 0 uses was obtained with only slight deterioration. if necessary. . while those for the lower half of the ring were placed in position during erection of each segment (see Fig. O n e hundred and twenty steel moulds were provided in the casting yard. Out of just under 28. The felt packings in the circumferential joint for the top half of the ring were fixed to the segments b y heat treatment before being delivered to the face. some rings of the Mott Hay and Anderson lining have been used for the first section of one of the drives for the Piccadilly Line extension t o Heathrow. and little damage occurred during handling and erecting. These segments.0 m. 85). 3 m Width of segment 0. 41.6 m Moulds Steel moulds. 120 number. Segments cast on site singly on their sides.0 .1 tonnes 1 MK 2 25' 0. Ordinary Portland cement. Average ring cycle times 2 hours 30 minutes.2 m3 /man hour 18 men in face Excavation Hand shield with clay spades. URS Infrastructure.1 75 m.9 m Length Tunnel 625 m Cut and Cover 136 m and 126 m Number of segments 22 MK 1 12Yz0 0. Plain circumferential joint with pre-shaped bituminous felt 3 mm thick.29 m Cover 7. DETAILS OF LINING Dates 1966-68 Strata London Clay Internal diameter 10. Caulking No caulking groove. Concrete joints ~ 2~8 days.7. Middle third coated with bituminous paint. Average building time 30 minutes concurrent with excavation Progress Maximum sustained 3 1 mlweek Average 18 m/week 3 ringslshift Excavation rate 1. Uncontrolled Copy. .63 tonnes 4 MK 3 14' Jacking space 2 x 2' Thickness of segment 0.TABLE 41 Details of expanded concrete lining for Heathrow Cargo Tunnel Licensed copy from CIS: URS.4 M N / at Convex/convex radial joint of radius 3. 04/03/2015.56 tonnes 1. Two rings were partly expanded within the tail of the shield before expanding the rings against the ground. The joints were tongued and grooved both longitudinally and circumferentially and the longitudinal joints were staggered. Details of the segments are shown in Fig.6 Collins lining: This lining. In the expanded lining a number of smaller segments may be used to cater for changes in ground conditions witho~rtaltering the size of the bead on the shield. consists of tapered wedge shaped segments of two types which differ slightly over the arc length. which was used for an experimental length of tunnel for a sewer in Stoke- Licensed copy from CIS: URS. ~ . to complete the ring. The segments of longer arc length are designed t o form a ring which can be erected without a tail to the shield and expanded t o the excavated diameter. Uncontrolled Copy.61 m by 0. URS Infrastructure.7. similar t o the Don-Seg lining. while the shorter segments will form a ring which may be built within the tail of a shield. were cast in concrete and timber moulds. With the expanded form of the lining the tubular links without the lead bars may also be used where overbreak occurs. were individually reinforced but as it was Corporation of ~ l a s ~ o The thought that the lining had a weak longitudinal joint two courses of brickwork were constructed as an internal lining. some 3 t o 4 m behind the face. The joints were . 7 3 and Table 42). Splicing bars were also cast into the two segments at axis level. The longitudinal joints are of the convex/convex type and two longitudinal holes are provided through the segments as shown. The taper was 1 in 10. Two semi-circular hoop bars were placed in the circumferential joint and fixed in small stop blocks cast into the groove at axis level. 86. which is placed from the face. The lining is not yet. generally available. which has been developed and used only by Sir Robert McAlpine. however. bolted and grouted. the part expansion and subsequent shoving of the ring out of the tail of the shield was successful.17. 610 mm long and 114 rnrn thick. In 1927 the lining was erected in compressed air for the construction of a tunnel in limestone under the River Liffey in Dublin.8.6 km was constructed The lining was used in 11 schemes between 1936 and 1961. Two grouted rings were erected and a series of experiments carried out with the expanding lining. For the trial length the segments. In the first case there was some difficulty in controlling the ring when the shield was shoved while in the second case. on-Trent in 1974.76 rn egg-shaped to 2. using different numbers of the larger and smaller segments. may be used in both an expanded and a bolted The experimental length of lining was later dismantled. 17.9 rn internal diameter 49 . The experimental length showed that the rings could be easily interchanged although some further development would be required.1 McAlpine lining: The McAlpine lining was first used in 1903 for an experimental tunnel for the w ~segments. The thickness of the segments varied from 102 mm t o 153 rnrn and segments of 127 rnrn and thinner were reinforced. 04/03/2015. The lining changed very little between 191 1 and 1961 when the lining was last used (see Fig. Steel tubular links are provided which are inserted in the leading and trailing edge of each ring and steel lead bars inserted into the two tubular links to give longitudinal continuity between the adjacent rings. The 'new' design incorporated a steel reinforcing hoop bar of 15 to 28 rnrn diameter in the circumferential joint and had staggered longitudinal joints. The lining. The largest scheme in which the lining was used was the West Middlesex Main Drainage Scheme in 1931-35 in which a total length of 38.8 Grouted smooth bore tunnel linings 17. when the tubular links were used. consists of a number of similar concrete segments with a small key segment. The lining was further developed during the next few years and in 191 1 several tunnels were constructed of sizes ranging from 0. The lining which has been developed from the Don-Seg lining. which were 114 rnrn thick. .Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. Uncontrolled Copy. pointed immediately after erection and then grouted after the mortar had set. The lining can be used behind a shield but ram pressures must be kept to a minimum to avoid damage t o the segments. 04/03/2015. In practice about 5 0 per cent of the tunnels are shield driven. Rates of progress for this scheme ranged from 2. The longitudinal and circumferential joints have a tongue and groove.2 Spun Concrete Flexilok lining: The Flexilok lining was the first standard range of grouted smooth . . 87).7 m per twenty-four hour day. gas main and pedestrian tunnels and have been constructed in the whole range of strata from soft silts to hard rock. over the centre half of the joint and a caulking groove on the internal edges (see Fig. The rings are grouted either at the end of the shift or earlier if the ground moves o n t o the lining . are bolted together to form the ring. The segments are cast with a grout hole and a screw threaded bolt hole and locating socket for the former ring attachment. some 24 hours before the segments are required in the tunnel. Rings subsequently dismantled at manholes showed that the grouting was satisfactory a n d t h a t the reinforcing bar was completely surrounded. When the bolts are tightened the bituminous strip in the radial joint is compressed to 1.when the grout is set the former rings are removed.45 m internal diameter with a 178 mm thick lining which showed that the segments could sustain a pressure of five to six times that of a conventional shield ram. The rubberised bituminous reinforced strip and primer are supplied with the rings. ~ ~ . a 3 mm thick. but few details are available of the progress rates in the other schemes. bolts and tie rods are hired t o the contractor. bore tunnel linings t o be manufactured and was developed in the 1950's after discussion with B R E ~ ~The lining was first used for a sewer scheme for the Borough of Ealing in 1958 and has subsequently been used in several hundred schemes in the United Kingdom for lengths varying from 140 m to 6. The maximum depth of tunnel constructed t o date is approximately 25 m. These tunnels have been mainly for sewers but include cable.8 to 3. The bolts are not fully tightened during the building operation to allow the key segment to be sprung into position.8. The bituminous strip in the circumferential joint is compressed either by the shield rams during the jacking operation or by tie rods tightened t o the adjacent former ring.5 mm thickness forming a substantially watertight joint and a line contact along the joint thus reducing point loads on the segments. attached t o the concrete segments. The joints are not usually staggered. On the ground surface. The lining has probably not been used subsequently with a shield. the former ring. URS Infrastructure. Trials were carried out in the mid 1930's using the lining for a shield driven tunnel of 2. Grout holes were provided in the segments t o the back of the lining and t o the groove. the segments of which have machined radial faces and whose radial joints coincide with the joints in the concrete rings. the first segment being placed in the invert symmetrically about the centreline. rubberised bituminous reinforced strip with bitumen primer is applied to the grooves and the steel former ring segments screwed t o the concrete segments. 50 mm wide. In the tunnel the 'former' ring segments. The lining was originally used in conjunction with an internal lining of brickwork but in the more recent contracts the brickwork has been omitted. of knuckle form. These charges are included in the price of a ring. The lining is erected on a steel 'former' ring. The number of segments per ring of lining is similar t o the bolted lining and thus to reduce the weight of the solid segments the ring width has been kept below 380 mm. For the West Middlesex Main Drainage schemeSo the segments were cast on site in steel moulds.Licensed copy from CIS: URS. Curved rings are available (see Table 43). 17.5 km. The steel and concrete key segments have parallel and not radial joints. Uncontrolled Copy. 753 m) and 6 ft 9 in (2. 66. Although the segments are slightly thinner than other smooth bore linings. 87).8 mm) Weight of segments 61 kg to 136 kg Number of segments to ring Note: Moulds Steel moulds with serial numbers Minimum concrete strength 41.4 M N / Ordinary ~ ~ Portland cement unless specified. High frequency vibration. The handling stresses should also be similar to other smooth bore linings as the segment length to thickness ratios are in the same range.6 mm) t o 7 in (177. which are designed to be interchangeable with bolted concrete linings. Details of Spun Concrete Flexilok lining Internal diameter 4 f t Oin(1. Two pins per segment are inserted in holes in the circumferential joint of the leading edge of the ring.2m) to 1 2 f t Oin(3. To allow for the future settlement of the tunnel and the accompanied strain. Erection Steel channel former ring Curved rings 4 ft 6 in . they are suitable for the whole range of depths at which these small diameter tunnels are generally constructed. The steel former rings and bolts must be kept well serviced and free from dirt.057 m)(see note) Width of segment 2 ft (610 mm) Thickness of segment 3% in (82. The bituminous strip is fairly soft and may extrude under heavy loads. the circumferential joint of the Flexilok lining has been redesigned and the tongue and groove omitted. 17.50 ft (15.3 Spun Concrete Extraflex lining: The Extraflex lining was developed in the middle 1960's specifically for the construction of tunnels in mining areas where it is expected that the extraction of minerals will be carried out in the future.8.24 m) to 1000 ft (304.TABLE 43 Licensed copy from CIS: URS. Uncontrolled Copy. these mate with slotted holes in the trailing edge of the next ring. For a ring of width 610 mm this is equivalent to a movement of approximately 5 mm at each circumferential joint (see Fig. In small sized tunnels the lining is erected in about 20 minutes rising t o 45 minutes for the larger diameter tunnels.658 m) i n 6 i n (152mm) stages.50 ft (15. 50 mm wide 3 mm thick rubberised bituminous reinforced strip + primer in joints. Spigot nylon pins. . slightly tapered at one end.8 m) radius The number of diameters in the range is likely to be reduced t o conform with recommendations in the recently published CIRIA Report No. are used for the longitudinal interlock between rings. Following discussions with various organisations.8 per cent which is the maximum strain likely to occur due to future mining46. 04/03/2015. and also 5 ft 9 in (1. including the National Coal Board (NCB).16 m) radius to 10 ft 0 in . URS Infrastructure.24 m) to 450 ft (137. The lining generally forms an accurately built tunnel with few steps between adjacent rings if the rings are tightened back correctly. Caulking grooves ?4 in (13 mm) to % in (19 mm) in both joints Joints Tongue and groove over middle section radially and circumferentially. a lining was designed capable of withstanding a horizontal strain of 0. URS Infrastructure. Licensed copy from CIS: URS.5 115 Coal measures 15 2.4 Charcon Tunnels Rapid Lining: The Rapid Lining was introduced in the early 1960's for use mainly in soft ground and soft rock. The lining is erected o n a 'former' ring which consists of a number of steel segments with machined faces.5 730 Sandstone 18. 1973 1. to give an overall reduction in the cost of tunnelling 47. Some blasting. 88). When large strains are anticipated a double flanged moulded cellular rubber strip with a neoprene protective skin is used of 16 mm thickness which fits over the spigots. is the last segment to be inserted and is not attached to the former ring. The lining is available in the standard range of internal diameters for the Flexilok lining but is developed and cast for each particular contract. Some blasting.37 500 Shales. The compression range of the seal is approximately 1 3 mm. of circumferential length of approximately 1 0 0 mm. l ~Nottingharn~ The lining was first used in 1967-68 for a sewer tunnel in Bunter sandstone at ~ a n s f i e l d in shire and has subsequently been used in two schemes for a total length of 1. the joints of which are staggered with the concrete segment joints and thus each steel segment is bolted to two concrete segments. Uncontrolled Copy.8. At Mansfield. The segments are cast horizontally in concrete moulds in a similar manner t o the bolted lining.34 km. coal mining has subsequently taken place and relatively little deformation of the lining has occurred. been used in most ground conditions but number of schemes throughout the United ~ i n ~ d oThe only occasionally in waterbearing strata.T o obtain a waterproof seal in t h e joint special sealing strips are provided. The ring is erected with a longitudinal joint on the centreline of the tunnel. Some blasting. The small key. Caulking grooves are provided on all internal edges. as an alternative to the bolted concrete lining. 197 1 1. clay and marl 15 2.4 m/ 1 shift day Hand. 04/03/2015. The lining was first used for a sewer tunnel in 1963 and has subsequently been used in a large n ~lining ~ ~ has . The 'former' rings are attached t o the segments in the tunnel. Mansfield 1967-68 Wrexham Dudley 17. When the lining was introduced tests were carried out to compare the stability of the lining with bolted concrete linings. Details of the tunnels are given in Table 44. When small strains of the order of 0. which showed very little difference in deformation under heavy loads (see Fig.4 m / l shift day Hand. TABLE 44 Details of tunnels with Extraflex linings Scheme Date Internal diameter m Length m Strata Depth ~n Rate of progress Method of excavation 1. The lining is designed to be used at depths of up to 4 6 metres although it has rarely been used at depths greater than 2 0 to 25 m. The joints are staggered from the segment joints to improve the watertightness.3 3 m / l shift day Hand.2 per cent are anticipated a sealing element of synthetic rubber is provided. the top . The segments are cast with a grout hole and two sets of wing nuts and plastic tube distance pieces for the attachment of the former ring (see Table 45). The circumferential joints are tongued and grooved while the radial joints are of knuckle form over the full width of the segment. and 9 f t 0 in (2. If different linings are used on a drive care must be taken when shoving the shield. and thus reduce manufacturing and mould costs47. Normal curing methods. Although the inside and outside diameters are similar to a bolted lining of the same internal diameter (and are therefore interchangeable).96 m ). The lining generally forms an accurately built tunnel with few steps between adjacent rings if the rings are tightened back correctly.8. The slight change in the internal diameters of the two sections could be streamlined with an epoxy mortar. 74 and Table 46). If the change over from the bolted lining t o the expanded lining occurs in the middle of a drive minor modifications are required. For the expanded lining the two top plates and the key require t o be replaced to enable a plane sided wedge to be used to expand the lining. The tongue and groove circumferential joints are closed either by the shield rams or by tie rods fixed to the adjacent former ring. In both joints.74 m) and 10 ft 0 in (3. TABLE 45 Details of Rapid Lining Internal diameter Segment width Segment thickness Weight of segment Number of segments Moulds I 1 1 1 I Characteristic concrete strength Caulking grooves I Joints Erection Curved rings Note: I 1 4ftOin(1.2m)to300ftOin(91. Steel channel former ring 50ftOin(15.6 mm) to 6 inches (1 52. for use in most ground conditions and which could replace three types of linings. a grouted and an expanded lining. the number of segments is larger with different shove ram positions. Tongue and groove circumferential joint knuckle joint over full width of radial joint. except for 6 ft 5 in (1. 17. The former ring. The lining. 66. URS Infrastructure. granolithic concrete or other material.segment of which is attached to the two top concrete segments. The erection times vary between 20 minutes and 45 minutes for the range of diameters. 04/03/2015.4 mm) 77 kg to 203 kg 9 to 14 Concrete moulds.5 Charcon Tunnels Universal Lining: The Universal Lining was introduced in 1970 in two forms. 2ft(610mm) 4 inches (101. the grouted bolted lining. the grouted smooth bore lining and the expanded lining. The former rings are removed after the grout has set. Ordinary Portland cement unless specified.5m)Radius The number of diameters in the range is likely to be reduced to conform with recommendations in the recently published CIRIA Report No. Cast vertically. Uncontrolled Copy. Licensed copy from CIS: URS. was first used for a section of the Greater London Council Roding Valley scheme in 1972-73 and has subsequently been used in a number of schemes and has an expanding market (see Fig.05 m) (See note).2m)to8ftOin(2. 41 MN/m2. which is not strictly an articulated lining due to the hoop bars. . bolts and tie rods are sold t o the contractor at the beginning of the contract and the contractor is credited an appropriate proportion o n return.44m)in6in(152mm) increments. The time to erect the 1. The two hoop bars onto which the segments are built consist of a number of steel bars curved to the correct radius and threaded at the ends. The segments at present are cast horizontally due to the difficulty of access. including the key. During erection care must be taken to ensure that the circumferential joints are in a plane and the toggles fully tightened. The first segment or two segments are placed in the invert and the bars inserted in the sleeves. After grouting. . tongue and groove circumferential joints Erection Segments threaded onto steel hoop bars The number of diameters in the range is likely to be reduced to conform with recommendations in the recently published CIRlA Report No. A flanged key segment is used with bolts having internal threaded holes which screw onto the threaded bars in the top segments. the toggles and washers are screwed onto both ends and tightened. The two bars for the next segment are then screwed onto the toggles and the next segment lifted and the bars inserted into the sleeves and the segment lowered into its correct position. when casting in the vertical plane caused by the former for the groove of the tongue and groove circumferential joint. This tongue and groove joint. an infill panel is fitted into the key segment. The segments are cast with grout holes and sleeves for the hoop bars.5 m and 1.60 m Segment thickness 125 mm to 150 mm Weight of segments 153 kg t o 2 4 0 kg Number of segments 7 to 1 3 Moulds Concrete moulds. Caulking grooves are provided on all internal edges. but without a shield the segments must be pushed to a close fit at the time of erection. The grouting chases for the sleeves are ground after removal of the mould. In the Roding Valley scheme the rates of progress with a shield were comparable with those for a bolted concrete lining although the lining took slightly longer to erect.Licensed copy from CIS: URS. When the number of segments. Cast horizontally. If a shield is used there is little difficulty in closing the circumferential joints. The next toggles are then screwed o n t o the ends of the bars and tightened and the process repeated until both top segments are in position. The recent modification of the continuous tongue and groove over the major part of the ring also allows the rings t o be rolled if required. are joined together with toggles.75 m rings in tunnels constructed to date have varied between 25 and 45 minutes. 66. otherwise there may be some difficulty in placing the key segment which may require the ring t o be dismantled to rectify the fault. 04/03/2015. URS Infrastructure. Uncontrolled Copy. forming a ring is an odd number there is a joint in the invert on the centreline of the tunnel and a double length bar is used to speed the erection. The depth of the tongue and groove has recently been increased t o 25 mm which allows the tongue to be located in the groove when packings are used around curves.0 m in 250 mm increments (See note). TABLE 46 Details of Universal Lining Internal diameters 1. Segment width 0. which are slightly shorter than the length of the segments. These bars. extends around the whole of the ring with the exception of the key.SO m to 3. The longitudinal joints are radial and plane.4 M N / ~ ' Caulking grooves Note: I in both joints Joints Plane radial joints. Characteristic concrete strength 41. The pea gravel. is piped t o the face. The tunnelling drives are between manholes which are normally 100 to 150 m apart. An uncured rubber strip 3 mm thick is placed in the joints to reduce point loads on the segments due to overburden and jacking loads. The first segment is placed in the invert on hardwood packings positioned at the knees and in the invert to support the segment at the correct level.6 Rees Mini Tunnel: The mini tunnel was introduced in 1969 as the first fully integrated tunnelling system in the United ~ i n ~ d o The m ~first ~ . A sealing ring on the tail of the shield prevents the pea gravel from entering into the shield. and inserted via the grout holes in the segments and into the crown from within the shield. have been in strata ranging from soft silts to sandstones but mainly in clays and soft ground. The radial and circumferential joints are of a knuckle form with caulking grooves.O. 89).2 and 1. 17.0 m tunnel could be constructed at the same cost and the standard range is now. The total length constructed t o the end of 1976 is approximately 29 km in some 80 schemes of length varying from 30 m to 1200 m. Although longer lengths are possible they become uneconomic as the rates of progress reduce due to delays caused by the increase in the time taken to reach the face t o deliver or remove materials. under compressed air. and the third segment is then positioned on the left hand side and the second segment sprung back to complete the ring. tunnel was constructed in 1970 and by December 1971 2. The three segments for the next ring are brought from the shaft on a small battery powered motor and bogie. The jacking loads should be kept to a minimum to avoid damage to the segments. which are always constructed with the special shield. The tunnels. A prototype of a rotating drum digger shield is at present being tested. URS Infrastructure. The lining was introduced to compete with open cut methods of construction and for the initial prototype the internal diameter was 0. Uncontrolled Copy. The tunnelling is normally carried out on a one shift basis and rates of progress of 3 to 10 rings per shift have been obtained.Licensed copy from CIS: URS. The ring consists of three 120' unreinforced segments divided into five sub-segments with 5 mm deep V-notches on the internal and external faces of the lining which act as stress inducers (see Fig.8.5 km of tunnel has been constructed proving the method. The shield and associated equipment can be set up and the first few rings erected within a week and the maximum sustained rate of progress reached early in the second week. into the void left by the tail of the shield behind the previous ring erected. The maximum depth of the tunnels driven to date is approximately 25 m. The system has now been sold to licensees who are the agents in the areas into which the United Kingdom has been divided. which is stored on the surface near the shaft. When the shield is shoved forward the hardwood packings are brought forward by the sealing ring on the tail to be re-used for the building of the next ring. 04/03/2015. The segments must be handled with care and stacked correctly taking account of the high length to thickness ratio. Following the excavation for a ring the shield is shoved forward on six rams and pea or other gravel is forced. The grouting of the tunnel is carried out at the end of the drive with a flyash grout. The erection of the ring is completed in a few minutes. A number of attachments are available for the front of the shield for tunnelling in different ground conditions. The system has not been used in compressed air to date. although this is under consideration. It was soon found that a 1. The second segment is then positioned on the right hand side and held in place by an arm from the shield. TABLE 47 Details of Mini Tunnel Lining Internal diameter Thickness of segment Width of segment Weight of segment mm mm mm kg 1000 67 600 105 1200 80 600 150 1300 89 600 18 1 . 1. With a rotating drum digger rates of progress of 20 to 30 rings per shift should be obtained.3 m internal diameters. The segments are cast vertically in a casting machine which compresses the concrete and enables the segments to be demoulded in 5 to 10 minutes (see Table 47).9 m. 1. In the original design the segments were 915 mm wide but this was later increased to 1220 mm.85 m thus reducing the weight of the segments. with concave/convex joints. The lining ring for the Mersey tunnel consists of 10 segments. The segments. at the contractor's request. screwed to the ends of the rods in the previous ring (see also Section 17. The segments above the roadslab were cast with an integral 6 mm thick internal steel facing plate. with minor modifications. the time of erection was decreased to about two hours. were cast in steel moulds in a special casting yard near the site. A new form of concrete lining was designed for the major part of the tunnel which was in sound rock. Uncontrolled Copy. After grouting and caulking of the lining. the remainder being lined in conventional grey cast iron. 04/03/2015. . has been used for the Dartford Duplication tunnel which is at present under construction under the Thames. The same concrete lining.8.7 Mersey Kingsway and Dartford Duplication tunnels: In 1966-74 the Mersey Kingsway twin Licensed copy from CIS: URS. which were lightly reinforced. The invert segment had a flat upper surface which was used as a roadway during the construction (see Fig. the heaviest of which is four tonnes. A similar lining has been used for the Dartford tunnel. To improve the erection techniques the tolerances for the casting of the segments were halved and.7. The width of the ring is 0. In this latter instance the lining has been used in the chalk whilst grey cast iron has been used where the tunnel is wholly or partially in alluvial deposits (see Table 48). thus reducing the number of joints t o be caulked and welded.3). This plate was secured t o the concrete by 12 mm diameter welded anchors at 130 m m centres and the back face was painted with bitumen to prevent bonding. For the erection of the lining the contractor devised a method of longitudinal threaded steel rods which passed through holes cast into the segments and connected t o couplings. URS Infrastructure.160y161. tunnels were constructed about 1.17. with slight "bird's-mouthing" between segments. In addition the number of longitudinal bars has been increased to give more control of the plane of the ring and thus speed the erection. The steel plates and cover strips were later painted to form the internal secondary lining of the tunnel. steel cover plates were welded over the joints and the voids behind grouted to give a substantially watertight tunnel.6 km downstream of the Mersey Queensway tunnel 18. Twenty-two rods were used around the circumference of the ring. 69). curved t o the radius of the tunnel. 32 m to MHWS 605 m concrete lined 273 m cast iron lined 1 MK A 1 MK B1 1 MK B2 1 MK C 2 MK D 1 MK K 2. Uncontrolled Copy.80 tonnes 2.10tonnes Segments Total weight 29. URS Infrastructure.8 1 tonnes 2.5 M N / at ~ 28 ~ drys Concave/convex radial joint Caulking grooves cast into segments Pilot .75 tonnes 2. MERSEY KINGSWAY Dates 1966-74 1972-78 Strata Triassic Sandstone of Bunter pebble beds wet and stratified.03 tonnes 4 MK C 2.TABLE 48 Details of Mersey Kingsway and Dartford Duplication tunnel linings DARTFORD Licensed copy from CIS: URS. 04/03/2015. overlain by boulder clay Alluvial deposits overlying chalk Internal diameter 9.3 tonnes Thickness of segment 0.mechanical shield 1 18 m to 30 m. 1 63 m/week No.22 m Moulds Steel moulds.60 tonnes 2 MK D 2. Minimum concrete strength 34.77 tonnes l ~ o t a weight l 20.80 tonnes 1.5 M N / at ~ 28 ~ days Joints Concave/convex radial joint Caulking Caulking grooves cast into segments Building time 2 hours Progress Average No.shield with impact hammer Main drive . Segments cast vertically in pairs in a yard near the site. 14 rings of moulds. 1 16 m/week No.63 m Cover 11 m to 27 m.blasting Main drive .shield with 4 impact hammers . 38 m to MHWS Length 2 x 2012 m concrete lined 2 x 210 m cast iron lined Standard ring 1 MK A 3.40 tonnes Steel moulds. 2 32 m/week Maximum No. 2 Method of excavation Pilot . 1 I 34.30 m Width of segment 1.03 tonnes 1 MK B2 4.02 tonnes 0.90 tonnes 1MKK 1. Segments cast vertically in pairs on site.95 tonnes 1 MK B1 4. 4 rings of moulds. 74 m/hr over best 24 hour period Average Excavation Type 1 Type2 Type 3 1 key 0.17. The lining consists of five reinforced concrete segments and wedge key in the crown (see Table 49 and Fig.7 hours over 24 hour period Building time 24 minutes over I week period Progress Maximum 0.50 m internal diameter service tunnel for the Stage 2 contract for the Channel Tunnel was lined with an expanded grouted form of lining The segments were cast with four pads on the back face which were thrust against the excavated tunnel. 14 sets of moulds with segments cast vertically in a special casting yard. 20 m water Length 230 m No.1 tonnes 3.5 tonnes . URS Infrastructure. 04/03/2015.26 m Moulds Steel moulds.50 m Maximum cover 80 m chalk.2 tonnes 3. 72). fill any outbreak and help t o seal the ingress of water. of segments 5 +wedge 2 2 1 Thickness of segment 360 mm Width of segment 1.23 m/hr over 2 week period Mechanical shield 3. Uncontrolled Copy.9 Expanded grouted concrete tunnel linings The 4.8 tonnes 0. Characteristic concrete strength 40 M N / ~ ' Joints Concave/convex radial joints Caulking Caulking groove on radial faces and on 1 circumferential face Average cycle time 1. TABLE 49 Licensed copy from CIS: URS. Details of Channel Tunnel Stage 2 lining Date 1974-75 Strata Lower chalk Internal diameter 4. Subsequent grouting was carried out in order to seal the fissures. During the initial excavation for the portals it was found that. Uncontrolled Copy. The ground was supported with stiff steel ribs at 0. The remaining four rams transmitted thrust forces along horizontal steel box columns to a point 9 m back where the thrust could be taken on the matured concrete through a transverse beam lodged in special pockets cast into the concrete. GIBRALTAR HILL MONMOUTH (1966-67) The Gibraltar Hill twin tunnels lie on the outskirts of Monmouth on the Mitchell Troy section of the A40 improvement scheme 56. Licensed copy from CIS: URS. on account of natural fissuring. especially with the flat circular arch (see Fig. APPENDIX 5 Cast in-situ concrete tunnel linings and teniporary ground support 18. Two pilot tunnels were constructed for each main tunnel. one at each side of the tunnels to provide support and guide rails for the shield.6 m centres on the M4 motorway Newport Bypass run beneath the populated Crindau Ridge between the River Usk and the Malpas Valley. The reinforced concrete invert was constructed as a separate operation. The tunnels were driven through Devonian Marls and Sandstones with some limestone beds which had suffered extensive faulting55 (see Fig. These tunnels are briefly discussed below and further data given in Table 50. Trailing tapered bars supported the roof between the shield and the concrete. In 1963 the excavation for the main tunnel commenced on a halfbench with the upper half of the excavation in advance of the lower half.CRINDAU TUNNELS (1%2-66) The Crindau twin tunnels at 14. Two further shields were installed in mid 1966 and the primary lining of the tunnels was complete at the end of 1966. The specification allowed for the use of drilling and blasting and a temporary support of steel arches and laggings. The tunnels were commenced in 1962 when a pilot heading was constructed in the westbound tunnel.9 m lengths. 04/03/2015. five of which could thrust against the lining when this had reached sufficient strength. 9 1). With the use of the shields 1 to 5. 90).18.6 m centres.5 m of tunnel were constructed per week per face in 0. A crown shield was designed with three horizontal working platforms which allowed excavation at a full face to be carried out and the original design of concrete lining to be cast immediately behind. The tunnels were driven through sandstones and marls with minor faulting. Two shields of 1.1 Cast in-situ concrete tunnel linings Details of a number of tunnels lined in cast in-situ concrete are discussed in the following sections. Where falls occurred the rock was shotcreted to prevent deterioration of the surface before concreting.1 Road tunnels: Four large diameter road tunnels have been constructed in the UK during the last fifteen years with cast in-situ concrete linings.1. A steel shield . Difficulties were encountered in the excavation and ground support causing large overbreak. large blocks of several tons could be disturbed by the excavator and it was thought that there would be difficulty in supporting the full width of the excavation in the tunnel. NEWPORT . 18.5 m length were installed in mid 1965 with hydraulic rams to support the face and nine shove rams. URS Infrastructure. The installation of the shields permitted steady progress and protection for the construction of the tunnels and at the same time limited the extent of falls. Only slow progress was made on all four faces during the next 12 months and it was then decided that alternative methods of tunnelling were required. 1 m per day. T h e shield 5. 92): a) A t o p heading l(a) for the central wall was excavated. one on each side of the tunnel and the concrete was placed at three levels. After the invert had been cast for 18 m in the east tunnel and 2 9 m in the west tunnel it was found that. Forty-five metres behind the face grouting was carried out with a PFA Grout at pressures up t o 138 k ~ / m ~ . 04/03/2015. Licensed copy from CIS: URS. which had a common central wall. The invert was concreted as a separate operation following on behind the shield. using a Greenside McAlpine tunnel heading machine advanced at 6. The central wall was concreted in two stages some way behind the excavation at an average rate of 11 m per week. The shield was shoved forward between 2% and 4 hours after concreting. The concreting was carried out using two pneumatic placers. and therefore distributed the forces t o the full cross-sectional area of the lining. initially o n t h e last three shifts of the week. which formed a stop end for the concreting. Two pilot tunnels were constructed at the sides of each of the two tunnels in which were laid rails set in concrete for t h e shield t o run on. Trailing headboards were provided for temporary support during shuttering and concreting. the arch did not require the support of the invert and the construction of the inverts was suspended until the drives were completed. The two shields were driven concurrently but staggered by a minimum of 18. b) This was followed by the excavation by the machine of the bottom heading I(b) which required no temporary support except at locations of fissures.22 m b y rams anchored onto a structural beam.8 m above the invert. in the short term. were constructed in stages as follows (see Fig.8 MN/mZ.was therefore proposed and accepted for each tunnel which would give immediate support and protection over t h e sides and t h e crown and which would be shoved forward off the cast in-situ concrete. URS Infrastructure. It was estimated that at 40 hours the concrete strength was of the order o f 13.3 m.3 m centres were the final link in the Birmingham Inner Ring R o a d scheme and pass beneath the southern half of Great Charles Street and Paradise Circus 57.22 m. Three shutters were provided. was shoved forward in increments of 1. 1 m above springing level and in the crown above the trailing headboards. The tunnels were driven through soft sandstone with layers of marl and perched water tables. The sequence of operations was a) The face was drilled to give 9 0 t o 100 holes while concreting of the lining was in progress b) When concreting was completed the face was blasted. and supported by colliery arches and concrete poling boards. Uncontrolled Copy.6 m long. c) The rock was then excavated and the periphery trimmed d) The shield was shoved forward e) The reinforcement and shuttering were fixed. t o be struck after 30 to 4 0 hours.GREAT CHARLES STREET TUNNEL (1967-69) The Great Charles Street twin tunnels at 10. 1. for a number of sections secondary grouting was necessary. BIRMINGHAM . The tunnels. Shutter vibrators were used together with poker vibrators for the walls. pulling 1. . 0 Progress m/week 1-5 7-12 see text Method of excavation Drill and blast Drill and blast Greenside McAlpine Hymac and hand excavation Drill and blast Temporary support horseshoe shield with travelling headboards horseshoe shield with travelling headboards steel arches and concrete laggings not required - - - 9 - .1 walls 3.TABLE 50 Road tunnels with cast in-situ concrete linings Licensed copy from CIS: URS.0x10.85 Internal Diameter m twin 7. Newport Crindau Monmouth Gibraltar Hill Birmingham Gt.22 Crown and central wall 6. URS Infrastructure. Uncontrolled Copy.5 See figure 840-1070 See figure 610 380 Shutters Steel Steel Steel Steel Minimum concrete M N / ~ ~ strength 24 26 21 Joint spacing m 0. 04/03/2015.67 Cover m 3-36 4.0 1.6-30 Length m 2 x 360 tunnel 2 x 280 2 x 198 tunnel 183.188 2 x 273 tunnel 2 x 230 253 Minimum thickness of lining mm 0.6x9.1 twin8.1 6. Charles Street Jersey Fort Regent Date 1962-67 1966-67 1966-69 1968-70 Strata Devonian marl and sandstone with some limestone Sandstone and marls.45-1. minor faulting Soft sandstone with layers of marl Fractured Granophyre twin7.9 base slab 3.65 x 8.2 x 10. FORT REGENT TUNNEL (1968-70) The Fort Regent tunnel at St Helier. d) The dumpling was then excavated using a Hymac excavator. Steel travelling shutters were used. which was highly fractured but with very little water. which is located with its centreline 30 m to the south of the centreline of the nearest of the old tunnels. The excavation for the crown of the east tunnel followed some 6 m behind the west tunnel. e) When the side walls were nearly complete excavation for the invert was carried out. excavation by hand for the crown of the west tunnel commenced. Jersey. When the excavation was complete the wall kickers were cast.65 m pilot tunnel from each portal and from a central shaft at a rate of 27. The average rate of progress was 10. c) When 1 2 m of the central wall were complete. JERSEY . however. Following this the side was concreted in two stages (3) and (4). the steel arch spacing was reduced to 0.6 m per week. The crown was later grouted with a cement flyash grout.61 m. These latter tunnels are discussed briefly below (see Table 51): WOODHEAD NEW RAILWAY TUNNEL (1949-53) The Woodhead new tunnel on the Manchester to Sheffield railway through the Pennines was constructed to replace the 100 year old twin single line tunnels whose linings had deteriorated 58.1. The tunnel was constructed at a full face by blasting using a twin articulated arm drilling machine for the charge holes. The twin track tunnel passed through shales with some sandstones which were jointed and fissured and of variable hardness.5 m from the foundations. f) The concrete road slab (6) was then placed.75 m (5). The crown (2) was concreted in 6. The new tunnel. . the Greenwood to Potters Bar tunnel which was in London Clay and lined with an expanded precast concrete lining. with the ground supported on steel arches generally at 0. Uncontrolled Copy. 04/03/2015.5 m per week per face.6 m and 0. where the crown of the tunnel was only 1.76 m centres. The excavation was self-supporting and no temporary supports were necessary.Licensed copy from CIS: URS.65 m by 3.1 m lengths some 18 to 24 m behind the face at a rate just under 10 m per week. Water was encountered but was only a major problem in one section of the pilot tunnel where saturated sandstone bands overlay the shales. At Lancaster House. The contractor drove a 3. These were bedded at the one end in the concrete wall and at the other on concrete blocks and concrete poling boards. 93). which was concreted in two stages of 0. fine-grained rock. The invert was cast separately. The rate of progress for the concreting was just under 9 m per week. was within the drainage draw down of the old tunnels (see Fig. these tunnels have been in rock and lined in cast in-situ concrete. URS Infrastructure. followed by the mass concrete lining of 380 m m minimum thickness in 9 m lengths. was constructed through Mount Bingham to connect the two parts of the town. The shale generally required steel ribs for support while the sandstone required no support. The tunnel was driven through granophyre. in 3 m lengths with the joints staggered with those in the crown to keep adequate support for the crown. 18.2 Railway tunnels: Very few new main line railway tunnels have been constructed during the last two or three decades and with one exception. a hard. horizontal placing was not possible and the method employed was inclined placing of the concrete. but over a seven month period an average of 2. the packing concrete was required to be placed as close to the face as possible. This. This fall caused some six months delay. When this lowering was nearly completed a large fall occurred. A by-pass tunnel was constructed to maintain the progress on the tunnel and as this was successful. The irregular overbreak made the packing behind the steel ribs difficult. additional by-pass tunnels were constructed. 24.5 m long. for the sides. URS Infrastructure. In poor ground. and then along existing track to James Street Station to form the Loop. using radial drilling from the pilot. 04/03/2015.a later date. Uncontrolled Copy. were used for the concreting operation with a theoretical number of uses of five per fortnight. shoulders or for the complete arch.8 m to the invert of the main tunnel to allow muck trains to pass and additional faces t o be worked. It was thought at the time that this would have had little advantage since it would not have prevented the falls that occurred though it would have delayed progress of the tunnel. A new single line tunnel from James Street Station connects new stations at Moorfields and Lime Street to Central Low Level Station. However. In practice this was not always maintained. concrete filling was carried out to the back of the ribs. The majority of the enlargement was carried out fullface with a steel gantry.4 m and 30.4 m3 bottom-opening hoppers to the location of the shutter. to a total length of 2900 m which enabled a total of nine faces to be worked. However. it was thought would reduce the over-break and the steel temporary support required. . where required. in two stages over a 2% week period. Average overbreak was some 450 m outside the theoretical concrete profile. running on rails at the sides of the completed excavation. equivalent to a total of 120 m of tunnel. near the Woodhead end of the tunnel which had been enlarged a few weeks previously.Licensed copy from CIS: URS. The concrete was grouted at. A burrowing junction is also under construction at Hamilton Square o n the Birkenhead side. thus maintaining continuous working. The first would have allowed the concrete arch to be cast close to the face. After mixing.5 m per week from the two ends of the tunnel.8 km of surface track which will connect the existing lines now terminating at Exchange Station under the city with the route of the old Central Surface Level railway. The link consists of 1 km of twin tunnel and 1. where five or six mixers were mounted. as discussed above. radial drilling and blasting proved to be impractical due t o the nature of the shale and was abandoned. This system has been used subsequently for road tunnels. due to the altered sequence of working this was impractical and the progress was too slow. The contractor planned to concrete at a rate of 36. LIVERPOOL LOOP AND LINK (1972-76) o is an extension o ~ to the ~Mersey ~Railway~ which at present terminates The Liverpool Terminal Rail ~ at Central Low Level Station. The invert of the pilot tunnel was then lowered 1. To help this packing problem. A new shutter system was designed to enable the whole arch to be concreted. The concrete was dry batched at the portal and transported down the tunnel in 0. The contractor planned to enlarge the pilot tunnel from the portals only.12 uses per shutter per week was obtained. Two interesting possibilities were considered but not implemented for the construction of the tunnel. The second possibility was to spray the exposed shales with gunite to prevent weathering. the wet concrete was taken in wet-mix hoppers and hoisted and tipped into a re-mixer above the pump input. The average pouring rate was 23 m3/hour per shutter and the system had a capacity of 30 hours uninterrupted supply. 3 0 m long and 21 m high. Two shutters. perhaps with a hooded shutter or movable poling boards to act as a protective shield. With longitudinal drilling from the four possible faces the progress would be too slow and additional faces were required to maintain satisfactory progress. Recent developments of this system might have been successful. On account of the long length of shutter. The concrete was pumped using five or six 102 mm diameter pumps at a continuous rate of between 4 and 5% m3/hour per pump. which carried the drilling platform and the steel rib handling equipment. 7 Station 5.5 24. 04/03/2015. the remainder shotcreted.7 x 7.2 horseshoe 5.TABLE 51 Railway tunnels with cast in-situ concrete linings Licensed copy from CIS: URS. 30.5 12 - 1875 m was lined with cast in-situ concrete.5 23 12 119 55 Drill and blast Drill and blast Dosco roadheader machines with some hand excavation Steel arches Steel arches where required for stability I Temporary support I 25 Station tunnels Minimum thickness of lining 4.9 x 8.4. Woodhead Harecastle Liverpool Loop Liverpool Link 1973-76 Date 1949-53 1965-66 1972-75 Strata Shales and sandstone Coal measures Triassic Sandstone.3 tunnels mm Shutters Minimum concrete strength Joint spacing Average progress concreting MN/~' m m/week Method of excavation 535 535 * 660 Running tunnels Station tunnels I I Running 1562 tunnels Station tunnels - 270 200 500 Steel Steel Steel Steel and timber 19 21 22. Uncontrolled Copy. Bunter and Keuper Internal Diameter m horseshoe 6. - .8 x 8.8 Cover m 15 t o 180 18 17-38 Length m 4889 Tunnel 2 18 Running 2855* tunnels r Portal to 255 portal i { $ Running tunnels Station 4. URS Infrastructure.5 tunnels - Steel arches i 22.5 x 7. The tunnels were lined either in bolted precast concrete segments or cast in-situ concrete and invert segments similar to the Loop tunnel. colliery arches at 0. When approximately % of the tunnel had been excavated.72 m internal diameter steel pipes for lengths of 363 m at the northern end and 1484 m at the southern end where the rock cover was equivalent to less than half the internal working pressure.4 km Cross Hands tunnel forms a part of the River Towy to Felindre Aqueduct 60. 254 mm by 152 mm. The tunnel was constructed in two stages. which reduced the width over a 30 m length. The nominal thickness of the reinforced cast in-situ lining was 535 mm.3 Water tunnels: Many water tunnels have been constructed this century with cast in-situ concrete linings. 94).8 m centres were used for temporary support and these sections were later lined with precast concrete invert segments and a cast in-situ concrete lining of horseshoe section.1.Licensed copy from CIS: URS. The overbreak was large and extended on occasions 6 m above the crown.45 to 0. Where the tunnels passed above the Mersey Queensway tunnel and below a sewer on that same line. further delaying the progress.6 t o 1. a moderately severe squeeze occurred over a length of 500 m. The lining was generally cast in-situ concrete except for large crown spans which were supported with arches of spheroidal graphite cast iron on concrete walls. with a turn round time of approximately 48 hours (see Fig. to less than 2 m. The tunnel was constructed through the Coal Measures by drill and blast methods with temporary support from steel colliery arches. All the station tunnels were lined in cast in-situ concrete. Some 35 per cent of the tunnel did not require support while some 44 per cent had ribs at 1. Where required. The voids were backfilled with lean concrete mix. with only a metre clearance. For the Link contract the running tunnels were also excavated using modified Dosco roadheader machines for both stages of the cross-section of the tunnel.3 m centres and 2 1 per cent at 1 m centres or closer. . Uncontrolled Copy. HARECASTLE TUNNEL (1965-66) The Harecastle new tunnel169 was constructed in the mid 1960's to replace the existing tunnel when the electrification of the London Midland line from London to Crewe was in progress. URS Infrastructure. Where no temporary steel supports were required the lining was of shotcrete. Two recent schemes are discussed below: CROSS HANDS TUNNEL . escalators and concourse tunnels were excavated by hand and supported on steel arches.RIVER TOWY TO FELINDRE AQUEDUCT (1968-72) The 6. cast iron rings were used. with drives from both ends of the tunnel. The 2. Measures were taken to protect the two existing structures but no movement was recorded. An adjustable steel framed shutter. 04/03/2015.9 m centres with laggings. At tender stage it was envisaged that the Loop tunnel would be constructed using a mini-mole type of machine through the Triassic Sandstones but the successful contractor proposed modified Dosco roadheader machines. at 0. 18. The passages.4 rn nominal external diameter tunnel was excavated through the Coal Measures by drill and blast methods and temporarily supported with 90 mm by 90 mm and 100 mm by 100 mm steel arches and steel laggings. 23 m long with plywood and steel facing was used for the construction of the lining. The Loop Station tunnels were enlarged by machine from the running tunnels and temporarily supported with extensive steel arches. Remedial measures delayed the drive but when these were nearly complete a roof fall occurred with a large rush of water. the top half of the horseshoe was excavated by machine and the invert was excavated either by machine or by hand. The tunnel was lined in 1. The concrete in the concrete lined section of the high pressure tunnel was 0. the steel in 9 m lengths was welded to form 27 m lengths of tunnel with a minimum of 0. the average -with one shutter of 45 m length .5 m with a maximum of 46 m. SCOTLAND (1969-74) The original Foyers power scheme was constructed in 1895 by the British Aluminium Company to provide energy for the smelting of aluminium. The access adit. Before concreting began the tunnel was cleaned out and a sub-invert cast.9 m or 3. Uncontrolled Copy. The new pump-storage scheme was designed in the late 1960's and constructed between 1969 and 1974 59. The cast in-situ concrete lined section of 1. The sizes and lengths of tunnels and shafts are as detailed in Table 52: .The pipes were rolled from 9. A 9. In addition drainage and access shafts and tunnels were constructed. t o an 18.3 m diameter shaft t o a 7. A short length of the aqueduct was in steel pipeline where it crossed the faulted valley at Glen Liath (see Fig.3 m by 2. The flow was regulated by a reservoir at Loch Mohr. Below the surge shaft the water passes down a 7. The low pressure tunnels were lined in 0. Drill and blast methods were used.61 m thick and was cast with a timber shutter in 9 m lengths. The reservoir at Loch Mohr was nearly trebled in area with water diverted through a 3. Where steel lined.3 m high concrete lined pressure tunnel which bifurcates into twin 4.5 mm thick steel in lengths of 9.6 m high pressure surge shaft. Grouting materials were delivered to the tunnel through two boreholes drilled from the surface.4 m machine shafts.3 m cast in-situ concrete which was poured in 3 1 m bays with a steel shutter. 04/03/2015. Concreting was carried out after two lengths had been welded in the tunnel. FOYERS PUMP-STORAGE PROJECT . Licensed copy from CIS: URS.9 m diameter steel lined pressure tunnels.45 m of cast in-situ concrete behind.LOCH NESS.93 m and 1. 3. Two steel shutters were used. and the overall average for concreting of the lining was 120 m per week. 6.1 m entries into 19. shafts and high pressure tunnels were constructed using drill and blast methods and supported with steel arches when required in poor ground.98 m. with 25 mm bars at 100 mm to 450 mm centres.9 m by 6. Steel arches were used when patches of poor ground were encountered. In some sections of poor ground very substantial temporary works were required. These lead into 4. which enabled the concreting and grouting processes to run concurrently. internal diameter was reinforced for 1322 m.6 m diameter steel lined shafts which taper to 3. from the River Fechlin.5 mm thick cement mortar lining was applied t o the pipes. For the mass concrete section. Average weekly progress was approximately 36. From Loch Mohr the water passes down a 2.1 km horseshoe tunnel.was 175 m per week with a maximum of 330 m. Between 10 and 17 pipes were installed per week.3 m.2 m. details of which are given at the end of this sub-section. The scheme used the head of 110 m between the top of the Foyers Fall and Loch Ness. 95).6 m.1 m by 2.8 km low pressure concrete lined tunnel of horseshoe shape. in areas of bad ground. This tunnel was mainly unlined with a concrete invert. The low pressure tunnel was generally driven through good stable granite except for two fault areas where rock bolts were used t o support the roof. URS Infrastructure. 1. A number of schemes are described below with further details in Table 53. Uncontrolled Copy. 04/03/2015.88 4. where hand excavation was used. precast linings have normally been used in these conditions.EAST SEWER (1971-74) This scheme which is a continuation of the Northern stormwater interceptor170 was constructed through an area where coalmining had been carried out at shallow depths in the 1920's and which had never been mapped.44 x 2.TABLE 52 Water tunnels in Foyers scheme with cast in-situ concrete linings Licensed copy from CIS: URS. The strata consisted of Triassic Keuper marls and sandstones overlying the Coal Measures. In the smaller diameters. Surge chamber 5.92 x 6.92 x 6.28 x 2.28 x 2. 1 No. in ground seriously weakened by a worked-out coal seam.75 x 2.15 x 2. The ground was supported with steel colliery arches.31 31 Concrete 18.59 3120 SHAFTS Lower control works Machine shafts .9 and 3.4 Sewer tunnels: In the past five years a number of larger diameter sewer tunnels have been constructed in soft to medium rocks and lined with cast in-situ concrete linings. 2 No.3 1 116 Concrete Low pressure drop shaft 7.58 7. BRISTOL . 4.32 44 Concrete Cross Gallery 2.37 31 Concrete High pressure drainage tunnel 5.06 x 1. URS Infrastructure.9 m centres and steel laggings.6 84 Concrete High pressure drop shaft 7.3 1 457 191 122 Steel and concrete Steel and concrete Steel and concrete Surge chamber adit 2.44 122 Concrete Fechlin tunnel 3.98 x 1.18 146 Concrete Drainage tunnel 2.33 2850 Concrete Glen Liath adit 2. generally at 0.33 23 Concrete Low pressure tunnel 6. Tunnels Internal diameter m Total length m Lining Lower control works 5.4 98 Concrete 18.18 x 5. The tunnel was aligned to be in the best tunnelling medium whenever possible. The excavation was carried out with a Dosco roadheader machine except for a short length. In poor .28 288 45% concrete lined High pressure tunnels 2 No.37 31 Concrete Drainage Gallery 1.32 6% concrete lined Concrete invert throughout 72 Concrete 19.75 88 17% concrete lined Surge chamber gallery 6. 3 40 80-140 per tunnel 25-30 Dosco roadheader machine Dosco roadheader Drill and blast Steel arches and laggings Steel arches and laggings Shutters Minimum concrete strength at 28 days 299 inside aiches giving 330 235 and 350 including arches see figure Average progress Excavation m/week Concreting m/week Method of excavation - - machine I Temporary support Steel arches and laggings . URS Infrastructure.59 x 2. Edinburgh Outfall Bristol Malago Bristol East Bristol Sewer Date 1971-74 1972-75 1973-76 Strata Triassic marl and sandstone overlying coal measures Keuper marl and sandstone Coal Measures Internal diameter m horseshoe 2.95 Cover m 9-2 1 7 .95 x 3.21 horseshoe 2 x 3.38 horseshoe 3.9 x 3.30 20-45 to sea bed Length m 1280 2 x 2475 588 2800 Minimum thickness of lining mm Joint spacing 300 inside arches Steel Steel 1 per tunnel Steel bIN/mZ 25 25 21 m 20 20 20 18. Uncontrolled Copy.08 3. 04/03/2015.TABLE 53 Sewer tunnels in cast in-situ concrete linings Licensed copy from CIS: URS.9 x 3. The rates of progress for the excavation ranged from 20 m t o 50 m per week. delivered to the location in agitator cars and placed with pneumatic placers. The average excavation rate was 25 to 30 m per week. and supported with colliery arches.91 m centres. 96). which will take the Pigeon House stream to the Malago. Average excavation rates were 2. Forward probing and grouting are carried out at weekends. 229 mm thick inside the steel arches giving an effective minimum of 330 mm. .2. The cast in-situ concrete lining was of 325 mm minimum thickness and cast in 20 m bays (see Fig. The concrete was delivered to the site by ready mix lorries and pumped to the location of the shutter.0 m centres and corrugated steel laggings. MANCHESTER (1970-7 1) A number of schemes were constructed using colliery arches and cast in-situ concrete linings in the early 1970's in Manchester 171. 99).5 km.61 m centres and for the sections with hand excavation t o 0. EDINBURGH . An invert slab of 152 mm to 203 mm thickness with mesh reinforcement was cast each week.7 m per shift. (see Fig. The excavated diameters ranged from 2 m to 3. 04/03/2015. of total length of some 2.5 to 3. Although this was further developed it was overtaken by the introduction of the "shell" type anchor which .128 18. The travelling shutter ran on rails and five sections were cast per week under normal conditions. two shutters were used. some seams of which have been worked.35 m with 230 mm of cast in-situ lining.2 Rock bolting Rock bolts fall into two groups. The average rate of progress for the excavation with the roadheader was 18 m per week with a maximum of twice this figure. The tunnels. depending on the type of anchor. the mechanical and the resin. BRISTOL . incorporates a small foul sewer and two tunnels from the Malago to the Avon. Uncontrolled Copy.1 Mechanically anchored bolts: The mechanical anchor was first introduced as a simple wedge in which the bolt was hammered against the bottom of the hole thus driving a wedge into the slot at the base of the bolt.65. URS Infrastructure. The concrete was mixed at the portal. 97). one tunnel incorporating the foul sewer. or more often in poor ground to act as lateral support to the arches and as a base for the track and other equipment (see Fig. 18. The turnround time for a shutter was 24 hours. The tunnel was lined with cast in-situ concrete. One tunnel. The tunnels pass through the Keuper marls and sandstones which overlie the Coal Measures.3 m thick cast in-situ concrete lining has recently been cast in 20 m bays. The outfall was being constructed in the Coal Measures through sandstones. the spacing was reduced to 0. shales and mudstones. using drill and blast methods. Two thirds of the tunnel are in marls with occasional lenses of sandstone. were constructed through very hard grey mudstones.46 m centres. A brick internal lining was normally used. 98). Dosco roadheader machines were used for the excavation and the ground was supported with steel colliery arches generally at 0. The ground support was colliery arches at 1.46 to 0. Licensed copy from CIS: URS. The 0.0 m to 2.OUTFALL CONTRACT (1973-76) The Edinburgh Sewer intercepter62 scheme connects all the existing nine outfalls to a new treatment works with a single outfall into the River Forth (see Fig.MALAGO SCHEME (1972-75) The Malago scheme6' will drain a large area to the south-west of Bristol.ground conditions. A cast in-situ concrete invert of 150 mm thickness was cast every week to act as transverse support for the arches and as a roadway. For normal flow only one tunnel will be used. the remaining third being completely in sandstone. these are discussed briefly below 63. 3 Other forms of anchor: Several other forms of anchor have been introduced to support the face while at the same time allowing machine excavation to take place . The formulation of the materials dictates the duration of the curing which can be as low as 30 seconds for the gel stage. In coal mines. five minutes before the resin hardens.2. Long hole dowels which are 9 t o 12 m long and filled with resin or fibre-glass and resin are also being used in increasing quantities in mines for reinforcing weak strata. which is difficult for bolts in a tunnel crown. length and shape of which differ depending on the bolt design or type of strata. Immediate support can be given to the face and the cost is considerably reduced. The rock falls were generally of medium size pieces. there was some shedding of the load with time caused by creep slip of the anchorage or by spalling of the rock.Licensed copy from CIS: URS. In some rocks there was also difficulty in obtaining adequate anchorage or pretensioning of the bolt. which use the same principle as resin bolts. which are anchored at one end. The dowels may be used in the coal face to resist the forces producing fracturing or in the roof to support broken strata during extraction. A lattice work arrangement of inclined hollow bamboo rods was placed and grouted over the difficult sections ahead of the mole. URS Infrastructure. have rarely been used in tunnels. Two basic types are available. One example of this type of rock reinforcement was for the Mersey Kingsway Tunnels 16'j1 61 where it was found that rock falls occurred at some locations when the main tunnel was enlarged from the pilot tunnel. For a permanent structure the life of the bolt must be similar t o that of the structure itself. The main difficulty of grouting is the satisfactory removal of the air. and an inner case with the catalyst. It was found that with these mechanical bolts. The anchor may be conical or parallel sided. sheath or skin which encloses the resin and filler. is now the main form of mechanical bolt. After drilling the hole the capsule is inserted and the bolt rotated at a high speed which mixes the two parts and starts the curing process.2 Resin anchored bolts: The cement grouted mechanical bolt was further developed with the injection of a polyester resin.a feature not possible for the anchor bolts described above. wooden fully grouted dowels. The use of these types of bolts is increasing annually. These difficulties were overcome by grouting the bolts with cement grout. Special air tubes are normally provided and the bolts should be grouted without the release of the tension . the number. In addition there is the possibility of attack by aggressive water. which in addition led t o grouted reinforcing bars being used as rock reinforcement. This bolt consists of an outer shell of steel feathers. and 24 hours before full hardening. The capsule consists of an outer case. These bolts were very popular in the 1950's in the coal mining industry but in that application have been virtually superseded by the resin bolt. while in the other system the resin and the catalyst are filled into the same skin which allows a local reaction between the catalyst and the resin which forms a diaphragm between them. The 38 mm diameter bamboo rods 4. 04/03/2015. Uncontrolled Copy. The feathers are wedged apart by a tapered nut which is pulled into the anchor by rotating or pulling the bolt. Two main systems are used in the United Kingdom. 18. which in turn led t o the resin anchor bolts with the resin placed in a capsule. In one system the inner and outer sheaths are separated by an internal plastic film sheath.though this is not always practical. the full column resin bolt and the point anchor bolt where only the base of the bolt is anchored.2. The dowels. .2 m centres and proved successful.5 m long were placed in 55 mm diameter holes at 1. are widely used. which are normally less than 2 m long. 18. For applications of sprayed concrete greater than 25 mm to 50 mm a mesh reinforcement should normally be used. 5 per cent to 10 per cent. In the wet process all the materials and the required amount of water are fed into the mixer before being conveyed to the nozzle where the air pressure is applied 68. but considerably higher strengths have been obtained for small applications. sand and aggregate when mixed are fed into a pressurised mechanical feeder and then into the delivery hose to the nozzle. considerably increased. when steel fibres are used but there have been cases where there was no significant change in the percentage of the rebound. Most applications in the United Kingdom use sandlagregate of less than 5 mm. Sprayed concrete or mortar consists of a mixture of cement. When steel fibres are included a greater thickness may be applied without mesh reinforcement. URS Infrastructure. The percentages of fibres vary between 1 per cent and 6 per cent but are normally in the range 2 per cent t o 3 per cent. the rebound does contain a higher percentage of fibres than the original mix with a corresponding reduction in the reinforcement on the face.the continuous arch rib. Admixtures may be used. In the dry process. including accelerators for areas where.35 to 0. With steel fibres only a small increase in compressive strength normally occurs. where the water and liquid additives. Certain published literature quotes very low percentages of rebound. The rebound for the first 25 mm of layer will be higher than for the remainder of the application. It has been suggested that the fibres in the rebound may be removed by magnet but this is unlikely to prove economic 69. however.25 mm to 0. a quick setting material is required to seal the face before the general application 66. The flexural strength of fibre reinforced shotcrete is. The introduction of steel fibres into the sprayed concrete may affect this rebound.4.4 Temporary arch and lagging supports 18.38 mm diameter and 25 mm long.68 Sprayed concrete may be applied by either the dry process or the wet process. The sandlaggregate cement ratio is normally about 4: 1 with a water cement ratio in tunnels of 0. due to the inflow of water. the cement. However. the thickness. although due to the greater ductility there is a larger load carrying capacity of the material after 'failure' when compared with ordinary sprayed concrete due to the random orientation. and above all the operators. These high strengths are partly due to the lower aggregate cement ratio on the face than the mix design. Uncontrolled Copy.4. The fibres may be 0. being richer in the coarser aggregates. and partly the compaction. The average compressive strengths of sprayed concrete will normally be in the range of 40 to 55 M N / ~ ~ . In tunnels the quantity of rebound will vary from 10 per cent to 20 per cent for sloping or vertical faces and up to 40 per cent for overhanging faces in the crown. is poorly graded with a low cement content and should not be reused.1 Steel arches: Various forms of temporary support using steel arch ribs are available but the ones used in the United Kingdom fall mainly into one group . The percentage will vary considerably between different equipment.67. the low cement water ratio. The quantity of water added is gauged by the nozzleman to give a satisfactory application and to avoid sloughmg.18. sand and aggregate.3 Sprayed concrete tunnel linings Licensed copy from CIS: URS. The forms as described in the literature7' are: . of the steel fibres in the cement matrix 69. materials and the mix design. which is the one generally used in the United Kingdom. 04/03/2015. This is a lower ratio than for other applications due t o the many vertical or overhead surfaces. on account of the rebound. if necessary. mainly in two dimensions. are added in the form of fine jets. although aggregate up to 25 mm have often been used. 18. The rebound. and water which is pneumatically applied at high velocity onto a surface. 100) may be of two segments which are bolted together in the crown or of a number of segments with a corresponding increase in the number of bolted connections. have corrugations and perforations (see Fig. 04/03/2015. 102) which are lapped by 120 mm or a multiple of 120 mm.Licensed copy from CIS: URS. URS Infrastructure. Following the excavation of a length of tunnel. It is easy and quick when the arch is made u p of two segments but is time consuming with more segments. The butt plates at other locations give initial full bearing. e) The full circle rib - used in squeezing ground. has not been used in the United Kingdom 72. The system was initially used for rock conditions where the rock could remain unsupported for two o r three days. The butt plates for the crown joint are normally fabricated to give a small bird's m o u t h which is closed t o give full bearing when the ribs are wedged. The laggings may be placed inside or outside the ribs and be made of timber. d) The rib. c) The rib and wall plate - two segment arch on wall plates. It is not usual in the United Kingdom to use invert struts but these are often desirable in weak rock and precautions must anyway be taken to prevent the foot of the arch tilting inwards. The longitudinal struts between ribs may be-either (i) steel rods cut t o the required length. a) The continuous rib - two segments or more with a joint in the crown. b u t if lateral forces build u p this may occur.at the same time acting as a roadway for the tunnelling operations. steel beams or channels. A stop end of perforated sheeting is fitted at the tunnel face end of the section and concrete is pumped into the space between the sheeting a n d the rock in 2 m lifts until the crown is concreted. 101). Uncontrolled Copy. which are profiled to the shape of the tunnel. The base plate welded to the foot is normally supported and wedged on wood or concrete blocks and a sub invert concrete base may be cast t o give lateral support . plate and post - the combination of (b) and (c). The shape of the support may be arched with vertical horseshoe shaped legs. threaded and bolted t o allow tension or compression. b) b u t t plates welded o n t o the two ribs which are bolted together with two or more bolts depending on the cross-section of the rib. The minimum thickness for operating and construction . with a total of four bolts. concrete. corrugated galvanised sheeting steel sheeters or liner plates (see Fig. This is a strong connection and is the usual method used in the United Kingdom. or (ii) steel angle spreaders with angle cleats bolted to the ribs.2 The Bernold system: The Bernold System has been used for several years on the continent but. arches removed from the previous length of concreted tunnel are erected inside the line of the final profile of the tunnel onto which the Bernold sheets are erected o n the outside. which are the quickest and the easiest to erect but which give a weaker joint. 18. c) Pinjointed connections. It has subsequently been extended to weak rock and soft ground conditions. b) The rib and post - two segment arch on vertical columns. In many conditions when the vertical loads are predominant there will be little tendency for the foot t o move inwards. The continuous rib (see Fig. The bolted connections may be made by one of the following methods7 1 a) a steel fish plate which is bolted t o both sections of the rib. The sheets have recently been used however as ground support for short lengths of tunnel in poor ground conditions for the NWA Kielder aqueduct.4. The use of porous bags pumped with grout is at present being investigated. with t h e exception of a short experimental length for the British Railways Liverpool loop. These sheets. The sheets which are available in 1320 mm by 1200 mm and 1080 mm by 1200 mm sizes and of thickness of 1 . which are jacked forward individually. URS Infrastructure. is available for soft ground conditions. The design of the thickness is based on principles similar to those used in the New Austrian Method. Uncontrolled Copy. Licensed copy from CIS: URS. A final sprayed concrete or other finish may be applied for aesthetic reasons or for a smooth finish. A crown shield of steel lances.1. In soft rock it may be necessary to shotcrete the roof immediately after excavation t o give temporary support. An alternative method of support for the sheeting is to attach it to the rock with rock bolts thus avoiding the use of the arches. 5 or 6 rn of tunnel are normally concrete in one section and the cycles can be repeated every two to four hours if necessary. act partly as a shutter and partly as reinforcement to the inner face of the concrete. 04/03/2015. See Section 8.2. The sheeting is erected and the concrete cast within the protection of the shield. The concrete is vibrated so that it just protrudes out of the holes in the sheeting. .reasons is 150 mm to 200 rnm. 2 or 3 mm. 2) Two rings with vibrating-wire radial pressure gauges in alternate segments around the ring. monitoring. The results of the monitoring while the tunnel was empty and during the filling operation were given by Tattersal et al4'. Two top segments were instrumented with gauges at three points o n one cross-section on each of the two segments.1. was first carried out in the United States of America in the 1930's and in the United Kingdom in the early 1940's. This particular scheme emphasises the large variation in stresses across a segment when the rings are erected without all the longitudinal flanges in contact.1 Instrumentation and monitoring Laboratory and site testing during the development of linings was first carried out at the beginning of the century. 3) One ring with vibrating-wire radial pressure gauges in all segments around the ring. 5) Two rings with one split segment with a pair of hoop load gauges and one split segment with facilities for jack loading. The monitoring was carried out for a period of 4 6 days. The instrumentation and monitoring of tunnel linings. The instrumentation carried out was as follows: 1) Two rings with hydraulic radial pressure gauges in alternate segments around the 10 segment ring.19. 19. In the one segment fairly consistent readings were obtained for stresses in the flanges and skin b u t in the other segment the stress in the trailing flange was four times that in the leading flange.Central Line extension to Ilford (1942): The instrumentation for the Central Line was the first instance of strain gauge readings being carried out in a tunnel in the United Kingdom. Since the 1940's a considerable number of tunnels have been monitored and much of the data have been published. facilities were provided for measuring the rate of intrusion of the clay.1 LTE .Ashford Common tunnel (1952): The Ashford Common tunnel which was at a depth of approximately 27 m was lined with a 2. 7) Changes in the diameter of a number of rings were monitored. Uncontrolled Copy. Hydraulic radial pressure gauges were also inserted in alternate segments around the rings.65 m internal diameter tunnel was at a depth to axis of 33 m. research and development Licensed copy from CIS: URS. The work was carried out by BRE95 . APPENDIX 6 Instrumentation. 04/03/2015. URS Infrastructure. however.2 MWB . It was found that the distribution of pressure remained irregular and the average radial pressure . 19.1. The combined stresses built up to the equivalent of the overburden stress in 10 days and increased by a further 10 per cent over the remainder of the period. The 3.54 m Don-Seg expanded concrete lining4'. gives data on many of the tunnels overseas. 4) Two rings with pairs of vibrating-wire load gauges in two split segments. 19. It should also be noted that the stresses were only measured in the two t o p segments and not over the full ring. Short summaries of many of the schemes are given below together with a note of the type of instrumentation in Table 54. 6) In three rings. Common Tunnel LTE Underground Tunnels (1952-56) x x x River Clyde Water Tunnel x x x Shell Building construction over LTE Tunnels x x MWB Tunnels x Clyde Vehicular Tunnel x x CEGB Sizewell Tunnel x x LTE Victoria Line x x x x x Elephant and Castle scheme above LTE Tunnels x x BAA Heathrow Cargo Tunnel Mersey Kingsway Tunnel x x x x Ely-Ouse Tunnel x LTE Fleet Line Stage I x x CEGB Severn-Wye Tunnel x x x x x x x x x Cleveland Potash BR Liverpool Loop x NWA Tyneside Sewerage Tunnels x x x x x x x Kings Lynn Tunnel x x x TRRL Chinnor trials x Warrington Sewer Channel Tunnel Stage 2 x x x LTE Fleet Line Stage 111 NWA Kielder Scheme x . x x x x x x . URS Infrastructure.TABLE 54 List of instrumentation in UK tunnels Scheme LTE Central Line Extension Lining stresses Hoop-load measurements Radial pressures Diameter measurements x x x Sub-surface movements Water pressures x MWB Ashford Licensed copy from CIS: URS. Uncontrolled Copy. 04/03/2015. These results showed that the flange stresses were several times the equivalent overburden stress. At the first site there were four 3. The vertical diameter decreased by 1. The vibrating-wire strain gauges were placed three each on six segments around the ring of 1 4 segments.24 and 0. Five rings. The average direct hoop stresses were of the order of 9 0 per cent o f the equivalent overburden stress in both tunnels although there were bending moments causing combined stresses 1. diameter readings were taken and water pressure gauges located at positions around the tunnel. The stresses in t h e second tunnel constructed were consistent with the equivalent overburden stress. high stresses were measured at axis.5 mm after the removal of the clay around the tunnel.5 times the overburden value in one of the tunnels. The water pressure in the tunnel increased the diameter by less than 0.3 m centres constructed in 1904. Similar results were obtained for the second tunnel.5 t o 2. At the second site there were two 3.5 mm.2. the stress built up to approximately 5 0 per cent of the overburden pressure while in the middle two tunnels it built up t o approximately 100 per cent.was generally between 0.underground tunnels (1952-1956): Between 1952 and 1956 BRE carried out instrumentation of a number o f tunnels between 3.65 m internal diameter adjacent station tunnels at a depth to axis o f approximately 3 0 m 977172. In three cases where existing complete rings had t o be removed vibrating-wire gauges were installed prior to the linings being dismantled 96. The combined stresses in the lining were approximately equal t o the equivalent overburden stress. At the third site the two 3. Uncontrolled Copy. In addition observations of t h e water pressure o n the ring showed that it was negligible. The changes in the diameters were small with a decrease in the vertical diameter of 1.5 m m in the horizontal diameter.8 m external diameter running tunnels at 15 to 18 m below ground level constructed in 1925-26. equivalent to 1. Between 1 9 5 4 and 1 9 5 6 BRE carried o u t the instrumentation of a number of rings in existing tunnels up to 5 5 years old at four sites on the Underground system where new access tunnels were to be constructed.5 mm.8 m external diameter tunnels were constructed in 1904 at 12.0 m internal diameter for the LTE. between 5 0 and 75 per cent of the overburden pressure.1.35 MN/m2 . Licensed copy from CIS: URS.85 m external diameter at 11.8 m internal diameter tunnels at 5. the two outer tunnels were instrumented. 19.4 River Clyde water tunnel (1953-1955): The 3.In the outer two.65 m internal diameter cast iron lined tunnel was constructed under the River Clyde partly in stiff clay and partly in sand at a depth of approximately 25 m 100. 19.5 . At the fourth site the monitoring was for one of two tunnels of 6. For the first tunnel the skin stresses were equivalent to the overburden stress while that for the flanges was 1. three at o n e location and two at another were instrumented with vibrating-wire gauges by the Civil Engineering Department at the University of Glasgow.0 m centres constructed in 1903 and a t a d e p t h of 2 1 m. 04/03/2015.2 m centres and at a d e p t h of 2 6 m . In the tunnel which was constructed first squatting took place during the construction of the second tunnel and. In 1 9 5 2 BRE monitored the stresses in four 7.0 times the overburden stress. After the excavation of the adjacent material the rings relaxed with an increase of 4 mm in the vertical diameter and a reduction o f 1.5 mm and an increase in the horizontal diameter o f 0. URS Infrastructure.0 times the overburden pressure.3 LTE . In addition.1.5 m and 7. . The : deformation of the lining is small.1. Three rings of the 3.7 Clyde vehicular tunnel (1954-1961 ): During construction of the pilot tunnel and the maintunnel. instrumentation of the linings was carried out by the Civil Engineering Department of the University of Glasgow 76. The crown of the Southbound tunnel was generally 1. . One ring of the main tunnel was instrumented at each of the same locations. 04/03/2015. Prior to the excavation the horizontal diameter was found to be larger than the vertical diameter in all cases by 23 to 80 mm. The results of this work have not been published to date. For the main tunnel the combined stresses followed a similar path rising to 80 per cent of the equivalent overburden stress at 14 months.Licensed copy from CIS: URS. Three vibrating-wire strain gauges were positioned at 15 locations around each of the rings. The total distortion was small and there was no interruption of the normal operation of the tunnel.5 m diameter tunnel at 30 to 50 m depth is negligible (1 to 2 mm).8 m internal diameter tunnels were lined in cast iron in 1901 and 1902. 19. These results have shown that the combined stresses build up generally to between 5 0 per cent and 80 per cent of the equivalent overburden pressure and that the overburden pressure has seldom been exceeded. The results showed that in the pilot tunnel in the drumlin the combined stresses built up to 35 per cent of the equivalent overburden stress before dropping and then gradually rising to 45 per cent of the stress. part of which was above e were instrumented by BRE to monitor the deformations and stresses in the LTE Bakerloo line 1 6 9 . The tunnel was a drumlin at the one location and in soft to firm laminated clay with silt and fine sand at the second. Uncontrolled Copy. Measurements were taken on twelve rings in the tunnel. The cover to the pilot tunnel was 13 to 15 m and to the main tunnel 7 to 9 m. The distortion of the lining due to the construction of a tunnel close by was less than 10 mm. The results have not yet been published.2 m below the excavated level although at the enlargements the cover reduced to 0. URS Infrastructure. ~ h linings the lining. d) Distortion of one tunnel when a second tunnel is driven within a distance less than one diameter from the first tunnel. Diameter readings were also measured. 19. c) Settlement readings at the surface.6 m. b) Deformation of the lining. The two 3. After the excavation was complete the invert of the tunnels had risen by 12 to 19 mm while the crown in the one tunnel had moved upwards by 25 mm at the periphery of the excavation but at the centre there was only 12 mm of upward movement. The tunnels were constructed in compressed air. a large excavation 200 m by 110 m and 12 m deep was taken out. The settlement at the surface due to construction of a 2. 19.5 Shell building (1957): During the construction of the Shell building on the South Bank of the Thames in London. At the second location the combined stresses in the pilot rose to 35 per cent of the equivalent overburden stress while for the main tunnel the average direct stress rose to 70 per cent before reducing to about a fifth of that figure. These measurements have included: a) Build up of stresses in the Wedge Block lining and the relaxation when filling the tunnel.6 MWB tunnels (1955-1 975): Various measurements have been taken by the MWB during the construction of these tunnels in London clay7'.1.6 m internal diameter pilot tunnel were instrumented at two locations with vibrating-wire strain gauges at three positions in each ring with four gauges at each position. In the other tunnel the crown moved little at the ends but rose by 12 mm over the majority of the excavation.1. which have not been published to date. Four vibrating-wire strain gauges were located at each of 10 positions around the rings and in addition diametral deformation of the lining was measured. c) Long term measurement of the tunnel lining deformation showed that the movements were less than 1.81 m internal diameter expanded concrete lining were carried out by BRE during construction of the experimental length for the Victoria Line. One ring in each tunnel was provided by Sir William Halcrow & Partners with datum points set in the faces of the skin and the flanges for measuring strains using a Demec gauge. 04/03/2015. At Oxford Circus the hoop load was found to be 9 0 per cent of the equivalent overburden load while at King's Cross it was only 75 per cent after the same period.35 m internal diameter tunnel.8 m diameter were sunk 0.3.1. At Oxford Circus the maximum settlement was only 1. The decreases in the vertical diameter were approximately 2/3rds of these values.1. . 19. partly due t o the number of tunnels constructed. The tunnel at a depth of 12 m was constructed in sand with compressed air.8 CEGB.86 m internal diameter expanded grey iron lining and of the 3.19. After 24 hours the tunnel linings had only distorted 1. further instrumentation was carried out as outlined below 19.7 mm and of the cast iron lining 3. The results.9 LTE Victoria Line (1960-1968): Instrumentation of the 3.5 mm. For the concrete ring four vibrating-wire strain gauges were fitted t o each of the 1 4 segments. In contrast the combined stress in the cast iron ring was approximately equivalent t o the overburden stress after 3% years. For the Victoria Line. it was 35 mm. Sizewell Power Station cooling water tunnels (1962-1963): Two rings were o w ~the ~ construction of instrumented by t h e Civil Engineering Department of the University of ~ l a s ~ during the 3. showed that the combined stresses in the two rings rose t o 80 per cent and 1 1 0 per cent of the equivalent overburden stress after six and nine months. in addition at Netherton Road ground movement tests were carried out by Sir William Halcrow & Partners. For the cast iron lining 12 vibrating-wire strain gauges were positioned spaced equally around the circumference. b) At Netherton Road and Gibson Square hoop load tests and. Two further shafts were constructed 0.20. The concrete and the cast iron linings squatted with an increase in the horizontal diameter of 10 mm and a similar decrease in the vertical diameter. Two unlined shafts of 1. The hoop load at 17 m depth was approximately 5 0 per cent of overburden.5 m from the tunnel. d) Settlement readings above the tunnels showed that values of 5 mm to 15 mm of settlement could be associated with each tunnel which passed in the zone of influence of a particular point.5 mm while at King's Cross.1. The average combined stress in the concrete lining was 65 per cent of the equivalent overburden stress after a period of 2 1 months.9 m clear of the tunnel.5 mm. The two rings distorted with the vertical diameters increasing by 1 mm and 8 mm respectively. URS Infrastructure. After six days the maximum increase in the horizontal diameter of the concrete lining was 2. Bending stresses equivalent t o 2% times the hoop stress were measured. Uncontrolled Copy. Licensed copy from CIS: URS. a) At King's Cross and Oxford Circus expanded steel linings were used for certain tunnels. The ground movements at various distances from the tunnel were measured and are detailed in Tables 7 and 8 in Section 7. In addition t o the stresses and deformations of the lining various load tests with trains positioned in the tunnels were carried out.4 mm. Deformations of the diameter of the rings were also measured. URS Infrastructure.5 m centres and a? a maximum depth of 3 8 m t o the level of mean High Water Spring Tide. 04/03/2015.5 mm. I 2 Mersey Kingsway tunnels 2A and 2B (1968-1972): Instrumentation of the two Mersey Kingsway tunnels was carried out by the Department of Mining Engineering of the University of Newcastle-upon-Tyne. 181 . The vertical heave in the invert was 7.1.Heathrow cargo tunnel (1968): During the construction of the 10. deformation and stresses for the grey iron lining and the experimental spheroidal graphite lining. The tunnels of 9. Uncontrolled Copy. I 0 Elephant and Castle shopping centre (1963-1965): Licensed copy from CIS: URS. t o 11 mm and there was little variation in settlement with depth to the crown. In the tunnel.The instrumentation for the second drive was installed ahead of its construction mainly from the first tunnel 106.63 m internal diameter were at 27. BRE monitored ground movements.3 m internal diameter Heathrow Cargo tunnel in London Clay instrumentation of the ground movements and of the linings was carried out by Sir William Halcrow and Partners 43.e) At Brixton. were in the waterbearing sand layer of the Woolwich and Reading beds at a depth of approximately 2 0 m. The surface settlements were limited.~histunnel was constructed with a cover of only 7 m. 3) The disturbance of the rock due to tunnelling was investigated by drilling a number of holes radially from the pilot tunnel and inserting displacement gauges outside the periphery of the excavation for the main drive and measuring the relative movement of the end gauges and thus the movement above the crown. 19.11 BAA . The changes in the horizontal diameters were found to be relatively small. which were lined in cast iron. The maximum heave of the tunnel crown was 13.1. erection of the lining and grouting. The ground movements are detailed t o Tables 7 and 8. In the early stages of the drive surface settlement readings were recorded on the ground transverse t o and along the centreline The ground movements were recorded in boreholes drilled from the surface. The maximum excavation to formation level was 10 m and the weight of the building was less than the weight of the ground removed. Part of this large complex of buildings was constructed over the LTE Bakerloo Line tunnels. 2) The interaction of the rock stress pattern due to the proximity of the two tunnels was investigated by drilling a series of holes from the pump room to depths of some 1 4 m and installing pairs of stressmeters to measure the stresses between the two tunnels and ahead of the second tunnel. The load at axis level of the tunnel after four years was equivalent to approximately 55 per cent of the overburden pressure. The instrumentation carried out was as follows: 1) The stresses adjacent to the tunnel were measured in a horizontal borehole from the mid-river pump room.5 mm which reduced t o 11 mm after construction of the building 173.1. some 1. Two 200 mm boreholes were drilled just outside the line of the tunnel and the horizontal movements measured with a plumb bob. At this stage the pilot for the second tunnel had been driven and the main drive for the first tunnel completed. A pair of hydraulic stressmeters were installed and the rock stresses measured during excavation. on account of special measures taken t o support the face. 19. 19.5 mm and the horizontal movements a t axis were also 7.2 m from the periphery of the excavation and parallel to the centreline of the tunnel 2A. Three 5 0 m m holes were drilled t o different depths and steel rods anchored at these depths to measure vertical movements on the centreline of the tunnel. The deformations and stress measurements have been detailed by Thomas 2 0. 5 mm after four years. four photoelastic load cells were installed in one ring and diametral measurements taken for three rings along the tunnel. the maximum being 1 4 mm. The tunnels. 5 m above the crown of the tunnel. The maximum difference was found to be a load in the trailing edge three times that in the leading edge. T h e sub-surface profile o f settlement tailed off quickly with distance from the tunnel. 4) The deformation of t h e lining following its erection was measured by trilateration methods for a series o f points mainly above axis level.1 m m with a trough of settlement extending 3 0 to 35 m on either side of the tunnel centreline.036 mm/min 1. Sub-surface movements were a maximum of 1 6 m m t o 1 8 m m at 1. 19. six rings were instrumented by Binnie and Partners 9 8 . 79780 T h e average surface settlement was 6. Piezometers were also installed a t two locations along the tunnel at 1. When the face passed t h e point of observation on the centreline of the tunnel 45 per cent to 60 per cent of the surface settlement had occurred while larger percentages had occurred off the centreline. The transverse movements a t axis level were 6 mm t o 8 mm at a distance 1.0 m from the periphery of the tunnel. 04/03/2015.196 m3/m equivalent to 1.15 CEGB Severn-Wye cable tunnel ( 1972-1 973): During the construction of the Severn-Wye cable on two tunnel a series of load. 19.146 m external diameter running tunnel. A slight heave was noticed ahea'd of the tunnel.1. ~ h etunnel was constructed mainly in t h e Gault clay and excavated with a full face machine. pressure and hoop strain measurements were taken by C K Haswell and . URS Infrastructure. The gauges were located near the inner and outer faces o f the segments.5 per cent of the area of the face o f t h e tunnel. 5) The strains in the lining were measured in rings in both tunnels at different locations with vibratingwire strain gauges cast in pairs into a number of segments in each ring. 55 m and 8 2 m depth. Two rings were instrumented with two load cells at four positions a t each of three locations at approximately 27 m . The results have not yet been published.5 m from the tunnel.5 m and 3.13 Ely-Ouse water tunnel (1969-1973): During the construction of the 2. if extrapolated. The Durham tunnel was constructed at a d e p t h t o axis of 3 0 t o 32 m. Water pressure readings were recorded to compare with tidal effects. Between 85 per cent and 1 0 0 per cent of the settlement had occurred when the face was 30 m beyond the point of observation. The h o o p loading in the lining was found t o vary between one-third and two-thirds of the equivalent overburden load. The measured horizontal movements were small.Licensed copy from CIS: URS. The vertical displacements were measured on magnetic rings o n the outside of inclinometer tubes while the horizontal movements were measured down the inclinometer tubes.54 m internal diameter Wedge Block lined tunnel.14 L T E Fleet Line at Green Park (1972-1 973) : Vertical and' horizontal ground movements were measured b y the Engineering Geology Laboratory of the Department of Geological Sciences of the University of at three cross-sections during construction of a 4. Diameter readings were taken in a number o f rings. 8 0 per cent t o 1 0 0 per cent of the sub-surface movements immediately above the crown occurred as the tunnel advanced a distance o f 2 0 m in the vicinity of the point of observation. In some rings there was a considerable variation between the load at the leading edge of the ring and that in t h e trailing edge. which. with only 3 mm movement parallel to the tunnel.1. Uncontrolled Copy. The calculated rate of settlement was 0. The volume of the trough was 0. 19. is approximately 22 mm at the crown.1.5 m above the crown.0055 mmlmin a t the surface and 0. 19. 19. which were lined with an expanded concrete lining. In addition the loads in several of the bolts were measured. vertical and horizontal ground movements were measured at nine boreholes on one crosssection and porewater pressure readings at one borehole.Fleet Line at Regents Park (1973-1974) : When the Fleet Line was constructed under Regents parkg1 the opportunity was taken by TRRL to take ground movements around the tunnels. similar readings were taken in the eight boreholes and.5 mm about 3 m above the crown.1. 04/03/2015. 10. Vertical and horizontal surface and sub-surface movements were measured at a number of boreholes. six boreholes were drilled outward from the periphery a distance of 4. Vertical and horizontal surface and subsurface ground movements were recorded at eight boreholes. with specially designed instruments. In the tunnel. The results showg6 how the bentonite holds the face. one ring was intrumented with three load cells and four earth pressure cells and in addition diameter readings were monitored for a number of rings.5 m and four anchors installed at different depths.1. 19.17 BR Liverpool Loop-Moorfields Station (1973-1 975) : Ground movements were measured during the construction of a large concourse tunnel at Moorfields by the Mining Engineering Department of the University of Newcastle-upon-Tyne g7. coarse sands and clayey sandlsilts.19 LTE . The difficulties of relating strain to stress in this situation render the results difficult to interpret. thus reducing the ground movements into the tunnel.18 LTE . and hoop strain measurements were taken on the inner surface of the two rings. porewater pressure readings were taken in an additional three boreholes. The maximum settlements were 40 mm at the surface and 45 mm at depth. . TRRL installed instrumentation t o measure ground movements and porewater pressure changes associated with tunnelling g6. has a cover of only 6 m of made ground and boulder clay below which is weathered sandstone. URS Infrastructure. The tunnel was constructed at a depth of about 10 m in sandy gravels. Following excavation of the next section of shaft. to compare with those at Green Park at a similar depth and lined in cast During construction of the first 4. Licensed copy from CIS: URS. in addition.reinforced concrete bolted rings. Uncontrolled Copy.0 m internal diameter was constructed through mudstone.1 -16 Cleveland Potash: Boulby Shaft (1973-1975) : Inward ground movements have been measured by the Department of Mining Engineering of the University of Newcastle-upon-Tyne during the construction of a shaft for the Cleveland Potash mine at Boulby lo? At a depth of 1050 m very weak ground was encountered. The point loads inferred on the concrete lining would normally have caused some signs of compression failure. 793g09g1. direct anchor vertical movements at four boreholes and piezometer porewater pressure readings at three boreholes. In the tunnel.1. Below this depth the movement was less. The 0.Fleet Line at New Cross (1973): During construction of the experimental section of the LTE Fleet Line at New Cross using the bentonite shield. a number of segments were fitted with acoustic strain gauges and earth pressure gauges were inserted behind the lining.6 m cast in-situ concrete lining was cast with a 225 mm void between the excavation and the ground. The maximum surface settlement was 21 -5 mm while the maximum ground movement was limited t o 27. sandstone and limestone at depths up to 45 m. which was of a horseshoe shape with concrete walls and cast iron arch segments. The normal radial load and pressure acting on the rings were measured. The tunnel of 3. 19. The concourse. Strains were measured and extremely high loads have been inferred from these results.3 m wide. The tunnel was constructed in several stages and ground movements were associated with each stage. When the second tunnel was constructed at a depth of 20 m.15 m external diameter running tunnel in London Clay at a depth iron of approximately 34 m. The calculated rate of intrusion at the face was 0. The horizontal movements b o t h parallel to and along the centreline of the tunnel were 2 mm when the face passed but then decreased.5 m .5 times the depth of the tunnel at axis level.024 m external diameter tunnel. The surface settlement commenced when the face was one or two times the depth of the tunnel from the point of observation and was complete when the face was approximately the same distance past the point of observation. Vertical and horizontal surface and sub-surface movements were measured. was constructed in compressed air.Ty ne Syphon (1974) : Measurements of ground loadings and lining stresses were taken by t h e Engineering Geology Laboratories of the Department of Geological Sciences of the University of ~ u r h a m ' " during construction of the 3. Horizontal and vertical surface and sub-surface ground movements were measured at four boreholes at one cross-section.Willington Gut (1974-1975): Measurements of surface and sub-surface ground movements were made by the Engineering Geology Laboratories of the Department of Geological Sciences of the University of ~ u r h a m at four ~ ~ boreholes during construction of the external diamete~ tunnel in silty clay. Uncontrolled Copy.The surface settlements were between 5 mm and 7 mm with a maximum settlement 1. The tunnel was constructed mainly in the Coal Measures at a depth of approximately 40 m.Hebburn contract (1973-1974) : Ground movements were measured b y the Engineering Geology Laboratories of the Department of Geological Sciences of the ' the construction of a 2.20 NWA Tyneside sewerage scheme .2 m of water as the face passed. The average maximum measured settlement above the crown was 12 mm.5 m above the shallower tunnel of 1 6 m m and h a similar position above the deeper tunnel of 11 mm. at 12 boreholes.002 mm/min at the surface and 0. In the free air section and in the compressed air section pressure cells were installed in the grout surrounding the lining and. six of which were along the centreline of the tunnel. 220 days after the tunnel passed the maximum settlement on the centreline was 66 mm with a settlement trough 60 m wide. The sub-surface results showed steeper curves of settlement . The tunnel.1.21 N WA Tyneside sewerage scheme . vibrating-wire strain gauges were installed at six locations around the ring.as was the case at the LTE Green Park contract. in a similar manner t o that used on the LTE Green Park contract. in soft. 40 to 50 per cent of the movement occurred before the face passed the point of observation.43 m external diameter cast iron lined tunnel. 19.1. 04/03/2015. The rate of clay intrusion was calculated t o be 0. The horizontal movements were small. 19. The average settlement at the surface was 7. 4. URS Infrastructure. The maximum radial horizontal movement was 12 mm at axis level.1. These values were in general less than those for the grouted cast iron lined tunnel. 19. The piezometer water level rose by 1. normally consolidated laminated clay. In addition ground anchors were installed in the line of the tunnel from a shaft put down in advance and face intrusion measurements were measured at the face during weekend stoppages.01 mm/min. The volume of the trough was 0. For the deeper tunnel large changes in the porewater pressure were recorded as the tunnel went past rising from 17 m to 19 m as the face approached before falling to 5 m as the shield passed and then gradually recovering during the subsequent 18 months.0035 mm/min at the soffit of the tunnel.22 NWA Tyneside sewerage scheme . which was at a depth of 17 m at the location of the instrumentation. The results of the instrumentation ring showed that after six months the hoop loads in the lining were 3 0 t o 5 0 per cent of the equivalent overburden load. at a depth to axis of University of ~ u r h a m ~during 7.0774 m3 /m equivalent t o 2. Licensed copy from CIS: URS.86 mm and the settlement trough was 22 m wide. in addition. Pneumatic piezometers were also installed to measure changes in porewater pressure. .4 per cent of the area of the face of the tunnel. 19. Movements of the order of 10 rnm were recorded. horizontal ground movements were measured by Binnie and Partners 8 2 . In the drill and blast section an approximately 3. the linings were: a) Fully bonded resin anchor bolts 1. was constructed to enable further adits to be driven into each of the three main rocks in which the main tunnel will be driven. Two deep boreholes were put down at different locations on the centreline ahead of the adit and special extensometers inserted at levels in the vicinity of the adit to measure rock movements as the face approached. At two or three locations in each section five holes were drilled six metres into the rock above the crown and shoulders and extensometers inserted at five different ievels to measure the differential rock movements. URS Infrastructure.35 m diameter tunnel was excavated and lined with four different linings: a) Steel arches and laggings b) Fully bonded resin anchor bolts.24 NWA Kielder scheme (1974): An experimental tunnel was constructed for the Kielder aqueduct Licensed copy from CIS: URS. The instrumentation was carried out by BRE in association with Babtie Shaw and Morton 70-An adit. 04/03/2015. ~ h etunnel was at a depth to axis of approximately 5 m. the excavation for the first part of the adit was carried out using drill and blast methods while for the second part a Dosco roadheader machine was used. inclined at 1 in 3. The horizontal movements were measured in inclinometer tubes installed in boreholes 1 m and 2 m from the tunnel. 1. In the machine driven section a similar diameter tunnel with a flat bottom for the machine to run on was excavated. The three adits were in the Four Fathom Mudstone.1. In the mudstone.19.9 m centres c) Resin anchor bolts as (b) with 100 m of shotcrete and mesh over an arc of 240' d) 100 m shotcrete and mesh over an arc of 240'.23 Kings Lynn mini tunnel (1974): During the construction of a 1 2 m diameter mini tunnel in silt in Kings Lynn.9 m centres and shotcrete over an arc of 240' b) Thin steel liner c) 100 m shotcrete and mesh over the full circle d) The final section was left unsupported. Different linings were used for sections of both parts of the adit and instrumentation was installed to enable comparisons t o be made not only between the linings but also the effects of blasting and mechanical cutting of the rock. in 1974.8 m long at 0. Double vibrating-wire strain gauges were fitted at six locations around the ring to measure stresses in the linings. Only blasting trials have been carried out to date in the limestone and sandstone adits which have not been lined. .8 m long at 0. the Four Fathom Limestone and the Nattrass Gill Hazle Sandstone. Uncontrolled Copy.1. c) Six rings in the machine chamber.1. 19. grouting after each ring. The vertical movements o f the ground were measured with a specially developed horizontal inclinometer. The vertical faces of the trench were instrumented with Demec points and the movements measured with a Demec gauge. 1. URS Infrastructure. Ground movements were measured and seven rings were instrumented. porewater pressure readings will be taken. O n a number o f schemes tunnels have passed with the clear distance between them less than 1 m.25 T R R L Chinnor trials (1974): A considerable quantity of instrumentation was carried out during Licensed copy from CIS: URS.ire load cells were installed in one ring. photoelastic stress meters.~hese included:- a) the advance construction of a 3 m shaft. b) four horizontal boreholes were drilled from the shaft. constructed in spheroidal graphite. The vertical and horizontal movements of the shaft were measured as the tunnel passed. In many of these cases special precautions were taken t o restrict any movement of the existing tunnel.1 -26 Warrington sewer ( 1975-1978): Measurements of vertical and horizontal surface and sub-surface ground movements are being taken b y T R R L in boreholes during the construction of this sewer with the bentonite shield. two above the line of the tunnel and two below. chemical consolidation of the ground or using an alternative lining in the vicinity of the existing tunnel.vibrating-wire strain gauges in segments and anchors for measuring the deformation of the lining were also used. The tunnel of 2. 19. In several instances the movements have been limited to 5 mm.19. These may include keeping the face boxed when excavation is not in progress. The shaft was lined with mesh and rock bolts. In addition. d) Ground movements were measured in an instrumented trench excavated across the tunnel line.28 m external diameter service tunnel for the Channel Tunnel was carried out by the Channel Tunnel Consultants and t h e Department of Mining Engineering at the University of Newcastle-upon-Tyne 91°4. t h e T R R L mechanical excavation trials in chalk at Chinnor 8589*108~109. The distortion. Vibrating-w. . c) vertical and horizontal ground movements were measured at a number of boreholes during the construction of the tunnel. The test programme included: a) The intersection of Colonel Beaumont's tunnel with the new tunnel provided a unique opportunity t o install instrumentation ahead of the advancing tunnel.75 m clear of the line of the 5 m external diameter tunnel. were instrumented. Uncontrolled Copy.27 Channel Tunnel Stage 2 (1974-1 975): The testing programme during the Stage 2 Contract for the 5. b) A number of rings were modified with compressible inserts in the radial joints to give a slower build u p of load in the lining. working round the clock while the tunnel passes.28 Tunnels crossing at right angles or on the skew: There are a number of case histories of tunnels crossing above or below existing tunnels at right angles or at a skew angle. settlement or heave of the existing tunnels have varied between 15 and 25 mm causing little distress to t h e lining.8 m external diameter is at a shallow depth.1. 19. The vertical sub-surface movements were measured with inclinometers and wire extensometers anchored into the ground. 04/03/2015.1. 13 m internal diameter cable tunnel passed at a depth of 6 m under a BR goods yard. The 2. ground surface readings are often taken before tunnelling t o establish the surface movement during construction. The levels were generally taken on road surfaces.~hesetunnels were generally at a depth of approximately 1 8 m t o axis level. kerbs. At the commencement of the drive the settlement was 75 to 100 mm with a trough symmetrical about the centreline. the two individual settlement troughs would have overlapped causing a maximum settlement of 20 mm 92 .19. For a single tunnel the settlements did not generally depend upon depth. which increased to 50 mm at the centre of the trough after the five phases of tunnel construction.5 m internal diameter Tyne Road Tunnel pockets of sand at a depth of 10 to 15 m. footpaths and door steps and there was a considerable variation in the results. as (a) above. d) in boulder clay with During the construction of the 9. There was negligible movement when the compressed air was turned off. diameter or rate of progress but more on the condition of the clay. When the compressed air was put on the settlement for the remainder of the tunnel was of the order of 10 to 15 mm. Similar readings were obtained during the construction of the NWA Tyneside Willington Gut tunnel.5 and 10 m 176. All sizes of tunnels were constructed under these schemes and on many occasions the tunnels were in close proximity. 04/03/2015. settlement readings have been taken on several occasions. which was constructed mainly on fill material. When a second running tunnel was constructed at 25 m.98 m internal diameter station tunnels constructed using 4. ground surface Licensed copy from CIS: URS. If the tunnels had been closer.~uringthe initial drive in free air. The 2. 929174 . g) Grangemouth. A number of these cases are discussed below: a) Settlement above a single 4. Precise levelling along the centreline and along transverse sections showed that the maximum settlement was 12 to 15 mm. Settlement during excavation of the pilot tunnels was 10 mm.29 Settlement at the surface: In addition to the instrumentation discussed above. As in (b) above the settlement over a number of tunnels in close proximity was approximately equal to the number of tunnels times the settlement over one tunnel. the maximum settlement was approximately the same. Uncontrolled Copy.0 m external diameter concourse tunnel and two 6. The tunnels were at 10 m centres. Following the introduction of compressed air the initial settlement during the driving of the tunnel was 25 mm which increased to 100 mm when the compressed air was taken off.7 m internal diameter sewer was constructed at Grangemouth in silt at a depth to invert of between 7. Where large diameter tunnels or a number of tunnels are constructed under built up areas. e) Tyne Cable Tunnel.1. A 1. settlement readings were taken at the surface. f) Irvine Sewer Tunnel. b) Settlements were measured over a series of tunnels iti London Clay consisting of one 6.1 1 m external diameter running tunnel for the LTE Victoria Line at a depth of 22 m in London Clay was found to be 10 mm with a trough approximately 30 m wide. c) LTE Victoria and Fleet Lines. settlement of the order of 100 m was recorded.45 m internal diameter sewer was constructed using compressed air in water bearing sand under open ground with a cover of approximately 6 m 93. URS Infrastructure. The maximum recorded settlement was 100 mm although the general settlement over that section was 30 to 5 0 mm 175. In general the settlement over one tunnel was found to be between 5 and 15 mm 19.1 m internal diameter pilot tunnels 92. 3 Development The testing o f linings during their development has been discussed in Section 7. This particular settlement record shows the effect of drag along the pipe. These tests showed that the configuration of the joint gave a n elliptical contact area and that for the Fleet Line. For the remainder of the drive the settlement continued to increase at a constant rate per metre of pipe thrust of 1 mm per 3 m of tluust. The settlement at a section at the centre of the drive was 5 mm and a t t h e end of the drive 7. 04/03/2015.2 Research The main research carried out b y universities and research establishments has been described in Section 7. Sunderland Polytechnic have carried o u t a number of settlement surveys as part of M. studies9 4 . These tests concluded that thejoint indeed needed to be reinforced and that the joint was then as strong as t h e segments.112 19.Sc. The embankment upon which the levels were taken had been constructed the previous year and was still consolidating. Uncontrolled Copy. This joint was convex/ convex with a radius of 3. i) Glasgow M9 Stormwater Sewer. settlement readings were taken over a 1.7. Similar types of tests were carried out for the Channel Tunnel lining with the concave joint reinforced t o avoid cracking. e) Model testing of ground movements at the University of Cambridge 110. URS Infrastructure. The 2. The latter profile was very similar to the first cross-section. These showed that the strength of the convex/convex joint decreased with an increase in the angle o f rotation. For t h e LTE Victoria Line. at the Engineering Geology Laboratories at the University of Durham 8 8. the maximum settlement on t h e profile reached 12 mm. the segments needed t o b e reinforced. to assess ground movements near a tunnel face.6 m internal diameter tunnel was constructed at a depth of 5 m in silt and stiff laminated clay in compressed air76. b) Laboratory testing of spheroidal graphite iron lining by BRE 20. For the Fleet Line and for the Piccadilly Line extension to Heathrow. The settlement profile at a section near the start of the drive was symmetrical about the centreline and. Initially. scaled down tests were undertaken which were followed by full scale tests at Fairlop using the same testing rig as that used for t h e Victoria Line segments. after the face had passed by some 1 0 m. c) Stresslstrain laboratory testing of spheroidal graphite iron at the Department of Mining Engineering of the University of Newcastle-upon-Tyne 106.5 mm.0 m external diameter thrust bore at a depth of approximately 5 m in grey boulder clay.h) Licensed copy from CIS: URS.8. 188 . The particular testing described here is that associated with the development of the concrete joints of the concave/convex or convex/ convex form. For a 3' angle the strength was less than half that at a zero angle. tests were carried out a t the Kinnear Moodie yard at Fairlop t o measure the rotation o f the joints. The maximum settlement attributed t o the tunnel drive alone was 3 0 mm. d) Laboratory extrusion tests. where the tunnels were up to 4 0 m in depth.111. 19. At the end of the drive the total settlement was 2 0 mm. These are: a) Examination o f bolting and lining stresses in cast iron and liner plate linings b y the Civil Engineering Department of the University of Glasgow 7 6 . similar testing was carried out.2 m 137. In one case. 100 Y. The theory however requires the solving of a number of simultaneous equations which can be very laborious. Computer methods of solving these equations are of a considerable benefit if a number of calculations have to be made. As can be seen this method is complicated and has thus seldom been used in the United Kingdom.1 Ph = 0. 16 Point loads Pr = PvCosy + PhSinr and Pt = the weight of the lining x Siny Five complicated simultaneous equations are then developed for the soil reactions F. 20.100%-0.2 Morgan's ~ e t h o d ~ O Deformation of tunnel lining and ground A tunnel subjected to ground loadings deforms to an ellipse causing bending moments in the lining.063(Hn - G) 25(Hn - Hw) h) H. URS Infrastructure. using constants given by Bull and summated to give the total values at each point and thus the bending stresses. (for points 5 to 8) Pv = -0.1 Bull's Method Bull's ~ e t h o d l 'developed ~ the previous design theories which had disregarded the deflection of the lining and therefore led to excessive values of the bending moments. 3 where + 0.063(Hn - P. APPENDIX 7 Design methods The design methods have been briefly discussed in Chapter 8. The methods are described in more detail in the following sections. equals the depth from the surface t o the point % equals the depth to the water table. Then it can be shown that Pv (for points 1 to 4) Pv = 0. one acting upon each of the divisions. 20. By conventional beam theory . 04/03/2015. The theory divides the ring into 16 equal divisions with the external loads combined to give 16 point loads. Uncontrolled Copy.20. 1 ThusPvand Ph can be calculated together with the weight of the lining for each point. Licensed copy from CIS: URS. The bending moments and thrusts can then be determined for the active and soil reaction forces. Cos 28) increasing from 0 at axis 2 t o po in the crown the bending moment M" = k 6 w2 For a continuous lining E is replaced by E/(1 .e. URS Infrastructure. Uncontrolled Copy. 04/03/2015.M axis = . pa = K6Cos28 where K = 3Ec a(l +V ) where Ec is the mean elastic modulus Poisson's ratio K the coefficient of ground reaction The effect of this loading on the lining stresses can then be assessed from the changes in the horizontal and vertical load due t o pa thus the bending moment M' = k m 1+w Similarly for a tunnel subjected to an active radial loading (p) p = % ( l . pr + pg = constant. Stability of the lining For an articulated lining it may be necessary t o consider the stability of the lining.M crown = 36EI where 7 6 is the distortion E Young's Modulus of the lining I Moment of inertia of the section of lining per unit width a The radius of the tunnel Considering the stress in the ground set up by the deformation and assuming no strain along the line of the tunnel i. At the state of collapse of a tunnel a3 .p2) where p is Poisson's ratio of the lining. The hoop loads in the lining are then Crown poa - + 3 Axis 2 poa + 3 4K& 3 + pwa 2K6a + pwa 3 The extreme fibre stress is then where P k pw is the pressure due to the water M A Z For other forms of active loading similar equations can be obtained. the incremental radial loading pa where r = a is given by Licensed copy from CIS: URS. where pr is the radial stressand pg the circumferential stress. The critical external pressure p is 3EI for a thin tube. pa' thus the ultimate stress can be calculated from equations (15). . and the extreme fibre stresses from A factor of safety of 4 is generally used on these stresses.Effect of consolidation for a tunnel in clay For a tunnel in clay the ultimate state will involve the effects of consolidation and swelling of the surrounding ground. by taking the elasticity of the ground into account. Uncontrolled Copy. The hoop loads in the crown and at the axis can then be calculated from the equations given above. For a saturated clay the consolidation settlement (pc) for no strain is Licensed copy from CIS: URS. Bending Stresses From equation (15) the moments can be calculated assuming full overburden pressure for po less that due to water. where A is the porewater coefficient Mv the coefficient of compressibility from the oedometer test pa' the extreme value of the final radial increment of stress in the ground due t o the tunnel This consolidation settlement will reduce the radial load between the tunnel and the lining by pa'' COS20 where pa'' = 9EI pc a4 . 04/03/2015.(24) but pa'' = Pa . on account of the reduction in bending moments. URS Infrastructure. The following graph150 illustrates how the bending moments developed in a rigid lining vary with the Modulus of Elasticity of the ground and shows the considerable saving in the cost of the lining. (23) and (24). Uncontrolled Copy. Ec ( k ~ l r n(log ~ scale)) 20.35 three times The maximum moments then become where ro is the external radius of the lining % the radius of the lining at the centroid to that at the extrados. . Bending in the elliptical mode The stress in the ground is calculated using the same method of approach as Morgan but with different boundary conditions.3 Muir Wood's Method Muir wood's1 l 9 design method corrects a basic error in Morgan's design method (Fig. 04/03/2015. URS Infrastructure. 17) and updates the theory from further experience.Licensed copy from CIS: URS.5 this value of K is twice Morgan's 0. A three dimensional stress condition is considered rather than a plane stress and plain strain condition. The value of K the coefficient of ground reaction becomes compared with Morgan if v equals 0.p.) wherep is Poisson's ratio of the lining. For a continuous lining E is replaced by E/(1 . Modulus of elasticity for soils. the ratio of the stiffness of the ground (to deformation i n the 'elliptical mode) to that of the surrounding ground where Rs = 3EI(1 + Q )(5 . Licensed copy from CIS: URS. 04/03/2015. If Rc is the compressibility factor and defined as the compressibility of the tunnel in relation to that of the surrounding ground then and Ap = p/(l + R ~ ) where j5 is mean value of the normal pressure between the ground and the lining Ap Uniform variation in p . T is the shear stress at axis. URS Infrastructure. it must directly support the full hydrostatic pressure. When it is greater it is possible to determine the loads transmitted t o the tunnel o n account of the ground water.Introducing the stiffness ratio Rs. Effect of shear forces between ground and lining The introduction of the shear force between the ground and the lining leads t o a further reduction in t h e maximum bending moment in the lining. It is shown that K becomes where p is the maximum value of the difference between the normal pressure between t h e ground a n d the lining and the mean value. 3r03 thus if the stiffness of the lining is matched t o that of the ground ie Rs = 1 the bending moment in equation (18) is half that in equation (16).6 ~ =) 3 E c s 3ro3 9EI Kq. Direct compression of the lining The stress around a circular tunnel causing a change in the uniform normal groundllining pressure. . Uncontrolled Copy. will give rise t o compression in the lining. It can be shown that where K is unaffected by changes in ground loading where k is the permeability q is the discharge of water per unit area of ground in unit time. and thus the radial deflection.(37) Groundwater When the permeability of the tunnel is effectively less than the ground. Consideration could be given to investigating upper and lower limits for the particular conditions t o establish how they affect the analysis.4 u ) Cos2O] 5 . curtisl2' when discussing the method developed different equations for the moment with no shear between the lining and the ground. Stc are normal and shear stresses where Q = Ec 1 ro3 E ( l + v ) ' m A (12) . For a lining of several segments the stiffness at the joint may be appreciably less than that of the lining. should be considered.2). thus where Ij < 1 I for an eight segment ring.60 + 4Q2 and with shear the differences are shown o n the graph the general equation for K is developed by Curtis to show that where Snc. Ie = 4 The hoop loads and stresses can then be calculated as for Morgan (see Section 20. thus Ie = + ($1)' Ij where Ie b I n >4 where Ie is the effective value of I Ij is the effective value of I at the joint n is the number of segments. Uncontrolled Copy.Application o f the method For the bending moment in the lining (16) a conservative analysis would be to use the initial conditions of vertical and horizontal ground loads. URS Infrastructure. M = 2 [P+- 2 (3 . 04/03/2015. Where the stiffness of the lining can be controlled equation (18) should be used and in the future when methods of controlling the compressibility rates are developed equation (36) and (37) should be introduced. Consideration of Licensed copy from CIS: URS. p ) + A) . 20.A)or . The method takes into account the tangential forces acting on the lining which have a large influence on the bending moments.0.RoCos$) and ph = Apv it is shown that p = Pt - 7 k [(l .3(3 + A)] Cos2@ 2 Ro 72 (1 .7. 04/03/2015. URS Infrastructure. k~ x is in the range of 1.(Pt .h)aSin2@and p0 = 7 -(H -0 . H It is shown that a = Ro where a is the ratio between the radius of the tunnel and the overburden. Uncontrolled Copy.Curtis modifying Muir Wood's equations shows that when considering groundwater the hoop thrust in the lining becomes Licensed copy from CIS: URS. This increase is given by = k(p+pt) where k is a function of p + pt and of p.p l ) Cb a2 = 1 + R4 B where where w R B Cb is deformation the radius at the neutral axis the reducing bending stiffness factor the coefficient of soil reaction Considering vertical and horizontal pressures pv = y(H .4 Schulze and Duddeck Methods Schulze and ~ u d d e c k developed l~~ a design method based on the elasticity theory. and the flow into the tunnel where Ho is the water head at radius r3 where r3 > rO. Considering the loading on the lining and the bending the differential equation is developed W(s) +2W(3)+a2Wl = !$.5 to 1. 3 R 4 . 0. for MF at the crown and Mu the maximum bending moment Ms at the invert.Nu the maximum ring load - Ns at the invert.A) a . URS Infrastructure.u A' z1 C is maximum stress under loading conditions T is minimum stress under loading conditions A is Area of lining per unit length and squat = -f + --s.R4 (pt .p) = 18K Sin 2@ then B ?% !! where K then Cb = k = 36 [3(1 . for NF the ring load in the crown. n and L ' in the equations. Uncontrolled Copy. Considering diagrams 7 .6(3 + A)] R4 B 5 where Ro Es is the Modulus of Elasticity of the ground. where No = -Rpo not including that load due to compressed air. Licensed copy from CIS: URS. The tangential stress component depends upon many constructional factors and the percentage to be included is difficult to assess. 9 and 1 0 in Schulze and Duddeck's paper coefficients can then be obtained for n ~ . Duddeck later discussed the design of tunnels. . hence NF and Nu can be calculated then CF = N~+"J A' Where zo C N u + M. 04/03/2015. It is probable that 5 0 per cent to 75 per cent o f the value should be included in the above theory but each case should be considered individually. - = 2K then N = No+N and for the deformation in the crown and a t the point of maximum moment and in the invert. URS Infrastructure. Stacking and handling segments Calculate the weight of the segment and assuming it is resting with the back face on the ground the bending moment in the segment can be calculated for the self weight and thus the stress in the lining.6 Temporary design conditions During the handlingloading. 4 segments may be placed at any one time. From the addition of these conditions the stress can be calculated. x 2 where p. Using this method the stacking stresses may be up to 15 times the stresses due to the self weight of the segment. In many cases these may be higher than the permanent conditions. Uncontrolled Copy. . For the stacking of segments on top of each other. This may normally be provided for by increasing the factors of safety if there is no provision for immediate structures.20. From the known distortions of tunnels an estimate can be made of the likely distortion of the tunnel under load. Half this total load may then be taken to fall in one side of the segment resting on the ground. b y conventional beam theory. Thus the bending moment due to stress distortion can be calculated by conventional theories. transporting and stacking of segments on the surface and down the tunnel and during the shoving of the shield high stresses may be developed in the segments. The hoop stress can be cilculated using conventional methods D Ring stress = p.5 Peck's Method design methods utilises the strength of the surrounding soils and considers four separate steps. is the vertical pressure at axis = y. For the consideration of buckling Peck uses the formula which is more conservative than Morgan's method. In the fourth steps consideration should be given to any known condition not already considered such as the construction of adjacent tunnels of basements to buildings or other structures. 20. 04/03/2015. thus the weight of 4 segments plus a dynamic effect equivalent to their weight should be allowed for. The provision of adequate hoop load in the lining of the anticipated distortion due to bending of buckling of other external loads not included in the above. Licensed copy from CIS: URS. moderate depth (1.lo) (B + Ht) Little or no side pressure.25 B Load may change erratically from point to point. It is generally accepted that although it may be on the conservative side there exists no better system of rock load assessment. URS Infrastructure. Squeezing rock.25 B t o 0.35 t o 1.7 Terzaghi's ~ e t h o d " The first rational method of evaluating rock loads appropriate to the design of steel arches was formulated b y Terzaghi.50) (B + Ht) Heavy side pressure.Shove force from the shield Calculate the number of rams that could act on one segment and the maximum force from each ram: Calculate the moment of inertia of the segment cross-section. . Swelling rock Up t o 250 ft. 3. Very blocky and seamy (0. Hard stratified or schistoseZ 0 to 0. required only if spalling or popping occurs. Licensed copy from CIS: URS. 04/03/2015. Steel arches permit some loosening of the rock and they are therefore designed t o support that loosened mass. 9. but chemically intact + Ht) 7. 6 . 20. Moderately blocky and seamy 0. In extreme cases use yielding support. Calculate the shear stress for loading directly onto. Squeezing rock.10) (B 8. Softening effect of seepage towards bottom of tunnel requires either continuous support for lower ends of ribs or circular ribs. 4. bending stresses are 3 1 .10 t o 2. moderately jointed 0 t o 0. Circular ribs are recommended. invert struts required. great depth (2.10 t o 4.5 (B + Ht)' Rock condition Rock load Hp in feet 1. Thus direct compressive force = A = force area and %L for the extreme fibre points 1 I thus the combined stresses in compression or tension. 5. Hard and intact zero Remarks Light lining.35 (B + Ht) No side pressure. Completely crushed 1.10 (B + Ht) Considerable side pressure. Massive.5 B Light support. Terzaghi's rock classification and rock load heights are given in the table below Rock load H in feet of rock on roof of support in tunnel P with width B (ft) and height Hp(ft) at depth of more than 1. Uncontrolled Copy. 2. and for the rams positioned midway between any transverse ribs or gussets in the segment. irrespective of value of (B + Ht) Circular ribs required. The method applies to tunnels excavated by conventional drill and blast methods where steel arches are set up a few metres from the face and blocked against the walls and roof. Some of the most common rock formations contain layers of shale. URS Infrastructure. The rock load or the limit of the rock load can be assessed from the table and thus a load diagram drawn showing the positions of the blocking points. the values given for types 4 to 6 can be reduced by fifty per cent. involving a downward movement of the roof. Hence. . where T is the maximum thrust sealed from the force polygon. 04/03/2015. If a rock formation consists of a sequence of horizontal layers of sandstone or limestone and of immature shale. The roof of the tunnel is assumed to be located below the water table. the relatively low resistance against slippage at the boundaries between the so-called shale and rock is likely to reduce very considerably the capacity of the rock located above the roof t o bridge. in such rock formations. The vertical loads (W) can then be calculated for'each point and then resolved to given radial force (F) and the tangential force Ft at 25' to the horizontal unless the tangent is inclined at less than 25' to the horizontal.86 % T t M max the stress Fr = A S h = R .Table (contd) Notes: 1. Licensed copy from CIS: URS. the roof pressure may be as heavy as in a very blocky and seamy rock. However. Uncontrolled Copy. In an unweathered state. the excavation of the tunnel is commonly associated with a gradual compression of the rock on both sides of the tunnel. Such so-called shale may behave in the tunnel like squeezing or even swelling rock. Furthermore.4 R3 . 2. If it is located permanently above the water table. real shales are no worse than other stratified rocks._C_ (2 l2 where C is the chord length R radius at neutral axis of arch. A polygon of forces can then be drawn first on a trial of 80 per cent of Rvt then corrected t o the maximum value of F in the load diagram. The rise of arc between blocking points then bending moment % = h T Mmax = 0. the term shale is often applied to firmly compacted clay sediments which have not yet acquired the properties of rock. BRITISH STANDARDS INSTITUTION. Edited by C A Pequignot. R B PECK. Trans. E BROCK and G WALTON. Proceedings of Advisory Conference on Tunnelling. Johannesburg 1970 1 pp 167-174 and 2 pp 72-75. ~ e ~ a r t m eof PRIEST. C. Discontinuity spacings in rock. J H. Int. J E MONSEES and B SCHMIDT. Eng. No 1 pp 41-9. 1973. Min. 04/03/2015. Instn.A. Transport and Road Research 1972. Licensed copy from CIS: URS. Geological Society 1970. British Standard No CP 2001. Ironfoundry statistics 1975. DEERE D U. Papers on London Underground Railways 1885-1929.1895 Nov Paper 2873. 17-22. URS Infrastructure. London. Uncontrolled Copy. Rock mass classification in rock engineering.80. Washington 1970. Geol. Min Metallurgy 1970. Norwegian Geotechnical Institute. PEQUIGNOT. Johannesburg 1976. Instn. REFERENCES ORGANISATION FOR ECONOMIC COOPERATION AND DEVELOPMENT. p 97-106. R LIEN and J LUNDE. Geological Society 1970. GEOLOGICAL SOCIETY ENGINEERING GROUP WORKING PARTY. . S D and J A HUDSON. Annual Report of the Transport and Road Research Laboratory. BIENIAWSKI. Sci. J. TRANSPORT AND ROAD RESEARCH LABORATORY. GEOLOGICAL SOCIETY ENGINEERING GROUP WORKING PARTY. Proc. Report on logging of rock cores for engineering purposes. Rock Mech. Technical description of rock cores for engineering purposes. Report on the preparation of maps and plans in terms of engineering geology. 1963. and Geomech. June 1974. MUIR WOOD. Civ. BARTON. Internal Report. and Instn.21. Rock Mech. A M.Vol 13. 1964. (HM Stationery Office). Z T. J. and a guide for estimating support requirements. THE COUNCIL OF IRONFOUNDRY ASSOCIATIONS. Report 1969'. Logging the mechanical characteristics of rock. Hutchinson Scientific and Technical. Metallurgy Sect. DEERE D U. FRANKLIN. N. Technology and Potential of Tunnelling. Final n tCivil Engineering. of Symp. 1976. Min. Draft Code of Practice for Site Investigation. Analysis of rock mass quality and support practice in tunnelling. Design of tunnel liner support systems. with some remarks upon subaqueous tunnelling by shield and compressed air. pp 39-73. Engrs. Tunnels and tunnelling. on Exploration for Rock Engineering. GREATHEAD. DEPARTMENT OF THE ENVIRONMENT. The City and South London Railway. pp 135-148. 1 . University of Illinois. Soft ground tunnelling. pp 50-79. MORGAN.Licensed copy from CIS: URS. B. Civ. Civ. Mersey Kingsway Tunnel: planning and design. Victoria Line. K R. design. 26. Civ. The development of high-speed soft ground tunnelling using precast concrete segments and tunnelling machines. Instn. Victoria Line Station construction. Paper 72703 Suppl. MORGAN H D and J V BARTLETT. Mar pp 37-46. Instn. Tunnelling with precast concrete. Engrs. DUNTON. C V BUCHAN (CONCRETE) LTD. programming and early progress.. Engrs. pp 1-24. Min. A contribution to the analysis of stress in a circular tunnel. Rapid Excavation and Tunnelling Conference. Engrs. Civ. Instn. 32. May. MORGAN. SMYTH OSBOURNE. Civ. W C. Instn. Catalogue. 21. ARMCO LTD. D and M FITZMAURICE. MEGAW.31.20. J A M. 1969 pp 397-451. Engrs. COMMERCIAL HYDRAULICS LTD. G S HOOK. 1897 paper 302 1. No 5. 27. S G. 18. 1971. Victoria Line: some modern developments in tunnelling construction. 29. Proc. Engrs. Instn. 1965. Technology and Potential of Tunnelling. C E. 25. 17. 30. CLARK. Mar. 16. Victoria Line: experimentation. Kirby-in-Ashfield. Civ. T M and C D BROWN. Instn. Civ. paper 72708. Part 1 1972 Mar pp 479-502. Engrs. CHARCON TUNNELS LTD. 31. R J and D A HARRIES. 19. HAY. PATTENDEN. J J LEE. Paper 72703 Suppl1969 pp 377-395 . H D and B L BUBBERS. Structural performance of a temporary tunnel lined with spheroidal graphite cast iron. TOUGH. Newmains. Engrs. J. 22. Catalogue. Luxembourg. H D. Letchworth. San Francisco 1974. Proc.. 04/03/2015. Instn.23. 1906. 24. pp 29-64. H S H. G L. 1945. Feb. Engrs. Instn. Geotechnique. Proc. URS Infrastructure. Tunnel shields and the use of compressed air in subaqueous works. J KELL and H D MORGAN. Engrs. Proc. COPPERTHWAITE. Proc. . Proc. Johannesburg 1970 1 pp 129-134 and 2 p 77. Instn. Instn. p 217. Archibald Constable & Co Ltd. Pre-formed linings in tunnelling practice. paper 72703 Suppl1970 Discussion pp 3 19-322. THOMAS. 20. Civil Engrs. Civ. paper 7868 Part 2 1976 Vol61 Mar pp 89-108. GROVES. Coleshill and COSTAIN CONCRETE LTD. pp 319-322. 1943. The Blackwall Tunnel. Proc. Bolted Lining Catalogues. P L MASON and D G THOMAS. Civ. 11. McBEAN. Tunnel linings with special reference to a new form of reinforced concrete lining. 28. Uncontrolled Copy. The Victoria Line: tunnel design. J. Suppl 1970 Discussion. 23. WATSON. pp 103-130. Proc. Civ. Tunnels and Tunnelling. T R M WAKELING and W H WARD. Vol60. SIR ROBERT McALPINE AND SONS. pp 852-866. W C. Vol 186. pp 190-212. pp 451-486. Proc. MINI TUNNELS INTERNATIONAL LTD. Civ. V o l 4 . Vol6. W H. C K. COLLINS. Engrs. An expanded/grouted tunnel lining. pp 140-173. URS Infrastructure. The construction of the Glasgow Main Drainage Works. Civ. Extension of the Piccadilly Line from Hounslow West to Heathrow Central. CHARCON TUNNELS LTD. Engrs. Civ. MUIR WOOD. EASTON. DONOVAN. Civ. Engrs. Engrs.44 (Dec). 1935. P A. (Feb) pp 257-276. 1 . 197 1. Apr. Instn. Old Woking.54 (Aug). a new method of tunnelhng in London Clay. pt I November. Inst. 1955. pp 323-338. (May) pp 302-31 7. Catalogue. 1961. Instn. Civ. F. Discussion 1970. H J. Rye Harbour. HASWELL. Discussion 1976. A M and F R GIBBS. 4 pp 400-47 1. Design Operation Specification. Instn. WARD. Nov-Dec. E W and F WOOD. Civ. Instsn. New tunnels near Potters Bar in the Eastern Region of British Railways. Jan.56 (Aug).21. Vol48. Tunnel under the Severn and Wye estuaries.2 1. Instn. No 2 . Civ. Engrs. Modern tunnelling methods. Discussion 23. Licensed copy from CIS: URS. pp 45 1-486. Expanded tunnel linings. T E R N S . DONOVAN. Pub. pp 46-53. TATTERSALL. Instn. Discussion 1952 6 (Nov) pp 768-772. Proc. The Thames-Lee tunnel water main. CUTHBERT. Civ. 1966. Engrs. Discussion 1962. Mar-Apr. SCOTT. S P. pp 11-34. No 6. Engrs. Proc. Engrs. Instn. 1976 Vol60. 5th International Congress of the Precast Concrete Industry. Instn. H J. May pp 191-218. 1937. C K. 18.118 pt 2 . A 75 inch water main in tunnels. 1974. Kirby-in-Ashfield. Vol6. Proc. Instn. Discussion 1974. London. Uncontrolled Copy. 1969. D G and A C LYONS. SPUN CONCRETE LTD. Smoothbore Linings Catalogue. (Dec) pp 690-704. Proc. 1969. pp 255-280. Engrs. Engrs. Thames Cable Tunnel.47 (Oct). pp 52-54. 1952 Pt 1 . pp 289-304. Instn. West Middlesex main drainage. Investigations into the design of pressure tunnels in London Clay. Proc. 04/03/2015. Jnl. Precast concrete tunnel linings. pp 463-617 . Proc. part 1 . 1973. Health. Proc. Civ. Proc. Jnl. 1912. A K and H D MORGAN. 1974. London. Apr. D M.HASWELL. JOBLING. The McAlpine System of Reinforced Concrete Tunnel Lining. pp 7 19-737. 1962. Tunnels and Tunnelling. Design and construction of the Cargo Tunnel at Heathrow Airport. The design of the Channel Tunnel. Development of Edinburgh sewage disposal scheme. Uncontrolled Copy. pp 45-62. FRANKLIN. 04/03/2015. C M. HOUGH. Concrete pipe jacking in the UK. Struct. Civ. May 1972 pp 161-170. H B. Proc. 1969. RYAN. ALBERTS. A C and J SCHOFIELD. Discussion 49. NO 1. 1954. J A and P F WOODFIELD. CROCKETT. Bulletin of the Ass. Engrs. Instn. Tunnels and Tunnelling. Instn. 1973. Proc. T A. Civ. Engrs. Department of the Environment. Cross Hands water tunnel. St. 60. J. R A. Engng. June 1972 pp 201 -205. Use of shotcrete in tunnel construction. (Transport and Road Research Laboratory). C and S BACKSTROM. No 3 p p 5 1-52. pp 506-563. pp 323-327. p 53-78.1972. No 3 . South Western Association. Geologists. BEALE. LANG. Crowthorne. Instant shotcrete support in rock tunnels. 1975. TRRL Report SR 212 UC. McCAUL. B C. Civ. Comparison of a polyester resin and a mechanical rock anchor Journal Institute of Mining and Metallurgy. pp 215-239. R R and G D THORNTON. Vol3 1971. Underground Services. Notes for visit of Instn. G 0 JACKSON and S G TOUGH. pp 34-37. Vol3. Construction of the Monmouth Tunnels in soft rock. Shotcreting on chalk: some preliminary trials.Tunnels and Tunnelling. Vol6. PIPE JACKING ASSOCIATION. Rock reinforcement. Instn. J. Vol4. T F. June 1971 pp 491-4100. SCOTT. Civ. pp 25-42. C and M D RYLEY. Engrs.1975. No 4. Tunnels and Tunnelling. DUNHAM. Tunnels and Tunnelling.a handbook for Engineers. construction of a three-mile main double line railway tunnel. C M. Techniques of pipe jacking. Vol53 No 2. (Cement and Concrete Association). pp 23-26. LYONS. London. 1972. P A and J I CAMPBELL. FOYERS PROJECT IN SCOTLAND WATER POWER. Civ. HOUGH. 1974 pp 389-41 6. Bri. Sept. . Licensed copy from CIS: URS.COULD. KIDD.1970. Great Charles Street Road Tunnel. Vol 1 . 47. pp 35 1-362. Engrs. Instn. Vol 1. Some aspects of resin anchored rockbolting. A S and J DUGDALE. Instn. Engrs. No 4. 1974. Standard Conditions of Contract 1975. 1976. V o l 5 . Engrs. Gunite . pp 376-385. MALAGO INTERCEPTOR PROJECT. R K.1976. Tunnels and Tunnelling. Woodhead New Tunnel. SIR OWEN WILLIAM AND PARTNERS. PARRY. Tunnelling in rock South Africa. Personal communication. URS Infrastructure. ATTEWELL. P B and I W FARMER. Measurements of ground movement and lining behaviour on the London Underground at Regents Park. W H. P B and I W FARMER. 1948. pp 380-395. paper 7270 S Suppl. Contribution to the panel discussion on: Deep Excavation and Tunnelling in Soft Ground. Crowthorne. The Next Decade. Licensed copy from CIS: URS. pp 225-258. R B. on Soil Mechanics and Foundation Engineering 1969. and 1 W FARMER. (Transport and Road Research Laboratory). Deep excavations and tunnelling in soft ground . Personal communic. pp 361 -381. 1976. 1976. on Soil Mechanics and Foundation Engineering. WARD. The performance of support systems in the four fathom mudstone. H B.W H. overconsolidated clay. Uncontrolled Copy. TRRL SR Report 199 UC. pp 320-325. Eng. University of Glasgow. D A and R G TYLER. Department of the Environment. Water Division.Discussion. Department of Civil Engineering. URS Infrastructure. Paper D2/G/3. Catalogue. ATTEWELL. Ground deformation resulting from shield tunnelling in LondonClay Can. 04/03/2015. WARD. Civ. Instn. D F H. P B.state of the art paper. SUTHERLAND. Proc. Prof. ATTEWELL. BERNOLD AKTIENGESELLSCHAFT. fissured. Ground disturbance caused by shield tunnelling in a stiff. THAMES WATER AUTHORITY. 7 t h Int. C. 1969. PHAROAH. Underground Engineering. 7th conf. McCAUL.Rock Tunnelling with Steel Supports by Procter and White. Engrs. Victoria Line . TERZAGHI. Department of the Environment. . D J COATS and P TEDD. Conf. Crowthorne. 1974 8. Commercial Shearing and Stamping Co. '76.70. ATTEWELL. Proc. Measurement of ground movement due to excavation of a shallow tunnel in lower chalk.ation. Personal communication. PECK. Jan. Chapters 1 to 5 . BARRATT. Small bore tunnelling for a sewer in difficult ground conditions. Tunnelling. K. W H. P B and I W FARMER. Report by University of Durham Engineering Geology Laboratories to Transport and Road Research Laboratory on Research Contract for instrumentation at Willington Gut. Geotechnical Jnl. Personal communication. London. NATIONAL COAL BOARD AND SIR WILLIAM HALCROW AND PARTNERS. Geol.11. J M MORGAN and J B BODEN. 1974. 1970 pp 329-333. Report by University of Durham Engineering Geology Laboratories to Transport and Road Research Laboratory on Research Contract for instrumentation Hebburn 1975. TRRL Report LR 684. Proc. 1976. int. WARD. 1976 (Transport and Road Research Laboratory). pp 93-94. with special reference to a new form of reinforced concrete lining. J A and J M MORGAN. L F and W H WARD. 04/03/2015. . Engrs.1943. B. H B. 95. 1955. pp 5 3-56. Conference on the correlation between calculated and observed stresses and displacements in structures. Engrs. 86. Tunnels and Tunnelhng. 96. Department of the Environment TRRL Report LR 653. N and T SKLUCK. paper 111 . Budapest. Personal communication. TOMLIN. Civ. Proceedings of the 4th International Conference on Soil Mechanics and Foundations Engineering. W H. NO 1. Existing stresses in several old London Underground Tunnels. AlTEWELL. Civ. Measurements on loads and strains in earth supporting structures. Personal communication. Settlement above shield driven tunnels in clay. Proc. 1971. SKEMPTON. Conf. Department of the Environment TRRL Report SR 92UC. No 3. thesis. SUTHERLAND. pp 256-259. 1974. W H. pp 623-640. BINNIE AND PARTNERS. Personal communication. Zurich 1953. 5. BARTLETI'. 87. No. Newcastle (1977). University of Illinois.Licensed copy from CIS: URS.484-486. Vol3. Personal communication. A W. pp 195-198. 93. BINNIE AND PARTNERS. HUDSON. 98. Personal communication. 97. 5 1 pp 5 13-5 39. Tunnels and Tunnelling. (Transport and Road Research Laboratory). EADIE. No 5. 102. Instn. -. Tunnels and Tunnelling 1977 Vol. on Rock Engng. 88.2 pp 162-166. 1974. (Transport and Road Research Laboratory). Surface movements caused by bored tunnelling. P B and J B BODEN. 99. 1957. 94. Conference on subway construction. SIR WILLIAM HALCROW & PARTNERS. (1969). 91. Tunnel linings. H S. 9 . Vol2. 101. Settlements and ground movements associated with tunnelling in soils. Settlements observed above a tunnel in sand. 100. WARD. pp 58-62. Ground deformation around a tunnel excavation in Bunter sandstone. COOLING. 1975. Proceedings of the 3rd International Conference on Soil Mechanics and Foundation Engineering. Crowthorne. Crowthorne. Vol20.D. SUNDERLAND POLYTECHNIC. URS Infrastructure. pp 370-371. Tunnels driven in clay. AlTEWELL. SCHMIDT. P B and I W FARMER. Measurement of ground movements during a bentonite tunnelling experiment. A horizontal inchometer for measuring ground movements. 89. Ph. BODEN. London. Uncontrolled Copy. Discussion Proc. 92. J B and C McCAUL. J V and B L BUBBERS. V017. WARD. 90. Instn. E T BROWN and M POTTS. pp 202-206. Engng. 1944. 110. No 3. Tunnels and Tunnelling 1975 V o l 7 . No SMl p 7 1-94. POTTS. Crowthorne. pp 529-539. Design and installation of the ground instrumentation of the Channel Tunnel. BULL. 11 6. R D. (McCraw Hill). on Rock Engng. Measurements of ground lining interaction pressure in an underwater tunnel in Coal Measures rock. ATKINSON. (Transport and Road Research Laboratory). Conf. B B and H BENNERMARK. Department of the Environment. R K DUNHAM. Tunnelling '76. Proc. 1 15. 1975. P B. 108. pp 1363-1394. 193.103. Licensed copy from CIS: URS. MUIR WOOD. Conf. The art of tunnelling (2nd edn in English) Akademiai Kiado. E L J . Cambridge. D J MACONOCHIE and A J REID. Vol5. Jnl. 414. S D. (Transport and Road Research Laboratory). 104. 105. pp 115-127 . pp 111-126. Geotechnique. HUDSON. Stresses in the linings of shielddriven tunnels. 107. Tunnels for roads and motorways. Shield and compressed air tunnelling. J A and C McCAUL. Site investigation for tunnelling trials in chalk. K. TRRL Report SR 176UC. HEBBLEWHITE. T R R L Report SR 161UC.465. HEWETT. B K . 1975. A. Crowthorne. 1972. Crowthorne. SZECHY. symp. Mech. ATKINSON. Research studies into the behaviour of tunnels and tunnel linings in soft ground. Tunnelling '76. 1975. ROARK. MUIR WOOD. URS Infrastructure. Newcastle (1 977). 1943. Soil. BRONS. J H. Div. Tunnelling '76. 1967. 1 1 1. W T LAWTON and D E CROOK. J H. Formulae for stress and strain. on the role of plasticity in soil mechanics. pp 8 1-87. Am. Department of the Environment. A M. Fdns. H D S MILLER and E L J P o n s . Vol. Soil Mech. In-situ ground lining studies for the Channel Tunnel project. Civ. Collapse of a shallow tunnel in a mohr-coulomb material proc. Uncontrolled Copy. Div. ATKINSON. J H and A M CAIRNCROSS. Soc. 1922 McCraw. 118. The influence of tunnel excavation on an adjacent shaft in chalk. CURTIS. Newcastle (1977). A method for predicting time dependent deformations in evaporites around a vertical shaft. Fdns. TRRL Report LR 730. 109. ATTEWELL. 114. Civ. Engrs. 119. pp 641 -661.25. 112. J. Proc. on Rock Engng. The circular tunnel in elastic ground. 1976. Am. Department of the Environment. 117. 1973. 106. (Transport and Road Research Laboratory). D J . 1 13. PRIEST. Collapse of shallow unlined tunnels in dense sand. Rock mechanics investigations in the second Mersey Tunnels. J. T L L ORR and D M POTTS. I W FARMER and J L WICKSON. J A HUDSON and J E HORNING. New York. Engrs. Soc. Stability of clay at vertical openings. Budapest 891. A M. 04/03/2015. SHAW. No 1. Geol. L M LAKE. R J . B H M and S JOHANNESSON. Report No. B C. Structures Symposium on exploration for rock engineering 1976. D J . E H GAYLORD. 1964. No 6 . RABCEWICZ. Geotechnique. V o l 6 . A J HENDRON. R E and H M EWOLDSEN. ZIENKIEWICZ. 1973. 0 C. 1st North Am. 1970 p p 74-79. Discussion. Symposium on large permanent underground openings. PAUL.1968. The circular tunnel in elastic ground. D J. 1964. Tunnelling in rock. 0 C. 129. Vol 18. p 237. 132. The use of rock bolts support in tunnel construction. L. CURTIS. Ingenieur . Proc. Use of the finite element method in tunnel design.120. ORTLEPP. Proc. 130. 123.26 March. 1976. Engrs. D F and Y S W. 04/03/2015. Viscoelastic tunnel analysis. 1976. Tunnels and Tunnelling. Civ. 128. January pp 19-24. Chapter 19. Water Power. Die neucre Entwicklung der stollenbautechnif osterr. Shotcrete support in rock tunnels in Scandinavia. W D. FRA-ORD & D 74-51. pp 56-66. Discussion. Geotechnique. 1974 pp 187-231.zeitschrift. KIDD. No 1 pp 13-24. ZIENKIEWICZ. 131. Land J GOLSER. C E KESLER. 0 S. Stresses in shield driven tunnels. CURTIS. Mining Research Centre. RABCEWICZ. University of Illinois. SCHULTZE. CECIL. Johannesburg. URS Infrastructure. pp 2 19-23 1. South Africa Instn. Rock bolt reinforcement in underground galleries. 133. Civ. Engrs. December. Inst. pp 169-175. The New Austrian tunnelling method. 125. 135. 1974. Research to improve tunnel support systems.26 March. June 1974. 121. Civil Engineering. LAUFFER. A J HENDRON and B MOHRAZ. 122. Rapid Excavation and Tunnelling Conf. 124. S L. . P J N. 127. Licensed copy from CIS: URS. PELLS. The circular tunnel in elastic ground. Geotechnique. Research Report R 233 Ottawa 1971. A M. p p 38-39. South Africa Instn. COATES. pp 231-237. H andHDUDDECK. Tunnelling in rock. State of the art of soft ground tunnelling. 134. 136. August 1964. Stress analysis of rock as a 'no-tension' material. GOODMAN. Beton und Stahlbetonbau. Uncontrolled Copy. 1972. November. Instrumentation of underground civil structures. B MOHRAZ and R B PECK. pp 5 11-5 15. S VALLIPAN and I P KING. 126. H. Vol 3. MUIR WOOD. London 1971. Oslo Sept. PECK. 1976. pp 88-92. 1974 pp 373-387. Principles of dimensioning the supporters system for the "New Austrian" tunnelling method. McGraw-Hill. Jan. R B. The finite element method in Engineering Science. Rock anchor design mechanics. pp 413-457. Water Power. March. 1974. (The Patent Office). BRUNEL. Conf. Limehouse to Rotherhithe Tunnel. London after air-raid damage. ANON. A M and F A SHARMAN. p 25. Department of the Environment. Proc. pp 43-5 3. 1945. ANDERSON. Proc. Civ. URS Infrastructure. Instn. p 473.137. BS 1452 1961 Grey iron castings. Discussion pp 168-1 69. Proc. Transportation Engrg. Partial face prototype at Stoke-on-Trent. Instn. Vol. 1975. LEENEY. A C and A J REED. (British Standards Institution). CP 110 1972. Modern cast iron tunnel and shaft linings. (British Standards Institution). 1974. Symposium on Transportation and the Environment. Advanced C02 process techniques used for production of cast iron segments. A H. Jnl. BS 2789: 1973 Iron castings with spheroidal or modular graphite. 150. Engrs. NATIONAL COAL BOARD. p 50. Engrs. BUILDING RESEARCH ESTABLISHMENT/TRANSPORT AND ROAD RESEARCH LABORATORY. Civ. Licensed copy from CIS: URS. Instn. 5th International Congress of the Precast Concrete Society. Civ. San Francisco. British Patent 4204. Prospects of Urban Highways in tunnels. CONCRETE SOCIETY SYMPOSIUM. Symposium Tunnel linings from prefabricated concrete. D. London 1966. 2 5 . 146. HAY. 148. Pressburg 1970. Precast concrete tunnel linings. No 6. Engrs. (British Standards Institution). 147. Proc. Tunnels and cut and cover method. H J B. Civ. The structural use of concrete PT 1 design. Civ. The construction of the Mersey Tunnel. Instn. Proc. 149. K R. 145. HAIGH. Future tunnelling in Britain. Vol 6. Calculation methods for tunnel construction and their safety. Engrs. 139. DUDDECK. 04/03/2015. 15 1. Subaqueous tunnelling through the Thames Gravel. 143. H. BRITISH STANDARDS INSTITUTION. BRITISH STANDARDS INSTITUTION. Foundry Trade Journal April 197 1 . Instn. Int. 140. pp 73-79. . Tunnelling as a social benefit. O'REILLY. M I. Emergency repairs to the Tower Subway. J G. 2nd Rapid Exc. D and M FITZMAURICE. M P and A P MUNTON. University of Southampton 1973 pp 2/21-2127. Uncontrolled Copy. 1936. 144. Committee on Geotechnics of tunnelling. (Building Research Establishment). Vol. BRITISH STANDARDS INSTITUTION. Engrs. 154. 130. 142. 2 . BRE Current paper CP 39/74 1974. 138. Tunnels and Tunnelling. 153. and Tunnel Conf. HARDING. The Shield. Proc. SMYTH OSBOURNE. Subsidence Engineer's Handbook 2nd Edition. Baker Street and Waterloo Railway. 141. 150. 1972. 152. pp 20-23. LYONS. MUIR WOOD. materials and workmanship. 173. construction and tunnel services. Instn. A F and H E WHITE. Engrs. 171. Instn. Proc. E W H and A A W BUTLER. 1 . The 5 n e Tunnel planning of the scheme. 30. pp 291-322. Proc. 170. 1955 pp 339358. Personal communication. Engrs. 157. 1. NORTHUMBRIAN WATER AUTHORITY. 159. 166. Civ. Engrs. 1965.51. Instn. Proc. pp479-501. The Victoria Line: the project. MIDLAND REGION. Discussion Vol36. Conf. pp 337-356. Tunnds and Tunnelling. HAXTON. Civ. 164. Instn. Clyde tunnel design. Engrs. CORPORATION OF MANCHESTER. Mersey Kingsway tunnel: construction Proc. Proc. MOTT HAY AND ANDERSON. COMMERCIAL HYDRAULICS LTD. Engrs. BRITISH RAILWAYS. 169. 156. Instn. Mersey Kingsway Tunnel: planning and design. Civ. Personal communication. 1972. C K HASWELL and E J PIRIE. Civ. J C and G S DODDS. Civ. Personal communication. Proc.1972. 1972. J Rand P A GRANT. Sewer tunnel linings in subsidence area. Personal communication.51. Vol 1 (1969) pp 49-50. 04/03/2015. 168. 158. Instn. Vol. Instn. MORGAN. 165. Proc.C. Engrs. ARMCO LTD. pp 193-212. pp 253-274.1966. KELL. Pt. ANON. Civ. Pt. URS Infrastructure. Some comparisons between measured and calculated earth pressures. 35. Civ. pp 189-200. Blackwall tunnel duplication. Personal communication. H G. 167. Uncontrolled Copy. Civ. FOLLENFONT. WARD. p 359. Licensed copy from CIS: URS. Instn. 163. pp 323-346. Elephant and Castle Shopping Centre. Mar. . Proc.1965. W H. Civ. St. CORPORATION OF BRISTOL. Instn. J. 33 (1966) pp 93-1 18. SOUTHERN REGION. Civ. McKENZIE. Pt. Proc. 160. GIFFORD. 30. 39 1967. Engrs.1967. Personal communication. Personal communication. Letchworth. 172. 162.155. H D. BRITISH RAILWAYS. The Dartford Tunnel. J and G REILLY. Instn. PROSSER. Engrs. MEGAW. Engrs. 1. Luxembourg. 2 4 1963. on the correlation between calculated and observed stresses and displacements in structures. pp 503-533. Clyde Tunnel: constructional problems. Engrs. T M and C D BROWN. Personal communication. KELL. 161. Prof. . SUTHERLAND. H B. Personal communication. 175. Department of Civil Engineering. Personal communication. Licensed copy from CIS: URS. Personal communication. SIR WILLIAM HALCROW AND PARTNERS. University of Glasgow. URS Infrastructure. 176. 04/03/2015. MOTT HAY AND ANDERSON. Uncontrolled Copy.174. 04/03/2015. Hay and Anderson British Airports Authority Sir Robert McAlpine and Sons Ltd British Railways Mersey Tunnel Joint Committee British Standards Institution National Coal Board British Steel Corporation North of Scotland Electricity Board C V Buchan (Concrete) Ltd Edrnund Nuttall Ltd Central Electricity Generating Board Nuttall Insituform Ltd Charcon Composites Ltd Northumbrian Water Authority Charcon Tunnels Lt d Post Office CIRIA William F Rees Ltd S P Collins Rio Tinto Zinc Enterprises Ltd Coriunercial Hydraulics Co Ltd Redland Fibaflo Archibald Constable & Co Ltd Spun Concrete Ltd Department of Environment Stanton and Staveley Ltd Department of Transport City of Stoke County Borough of Derby Thames Water Authority Corporation of Edinburgh Tunnels and Tunnelling Corporation of Glasgow. Upper Stour Main Drainage Authority Sir William Halcrow & Partners Water Power Head Wrightson & Co Ltd Sir Owen Williams and Partners Howard Humphreys and Sons . Uncontrolled Copy. URS Infrastructure.The authors and the Transport and Road Research Laboratory acknowledge permission from the following organisations to reproduce photographs and figures: Licensed copy from CIS: URS. Anglian Water Authority Armco Ltd Institution of Civil Engineers Greater London Council Babtie Shaw and Morton London Transport Executive Bernold Ltd Miller Bros and Buckley Construction Ltd City of Birmingham Mini Tunnel International City and County of Bristol Mott. Longitudinal joints of primary lining Thickness of secondary lining if required Thickness of grout (a) Cross section through a tunnel Circumferential Lonqitudinal and circumferential faces mayVbeflat or curved (see Section 5. 1 VARIOUS FORMS OF TUNNEL LINING . Uncontrolled Copy. URS Infrastructure. 04/03/2015.3) concrete segment (b) Detail of bolted segmental lining (c) Detail of smooth bore segmental lining Solid precast concrete segment Excavated profile Longitudinal and circumferential faces may be flat or curved (see Section 5.Key segment Finished internal diameter if secondary Ordinary segment Licensed copy from CIS: URS.3) (dl Detail of expanded segmental lining Fig. URS Infrastructure. 04/03/2015. Uncontrolled Copy. .Licensed copy from CIS: URS. Curve (a) (b) (c) (d) 2 19th century and early 20th century heavy linings for waterbearing strata 19th century and 20th century light linings standard imperial linings used since 1930s metric linings used by LTE on Fleet Line Stage 1 3 4 5 6 7 External diameter of lining (metres) Fig.Licensed copy from CIS: URS. 3 WEIGHTS OF GREY IRON TUNNEL LININGS 8 9 10 . URS Infrastructure. Uncontrolled Copy. 04/03/2015. URS Infrastructure. bolt holes 36 No.d.84m i. 4 GREY IRON LININGS. 1890s AND 1960s .8mm dia.8mm dia. Uncontrolled Copy. bolt holes with 25.4mm dia. tunnel Fig. Circumferential joint Flange thickness Longitudinal joint (Both joints made with timber packing) City and South London Railway (1886-1890) 25.Licensed copy from CIS: URS. bolts Unmachined circumferential joint Section through tunnel London Transport Victoria Line Linings (19631969) Detail of machined circumferentialjoint for 3.4mm dia bolts Longitudinal joint 31. 04/03/2015. 31. Licensed copy from CIS: URS. 04/03/2015. Uncontrolled Copy. Plane joint (b) Convex/convex joint (c) Concave/convex joint 7 - (d) Tongue and groove joint Double joint Fig. URS Infrastructure. 5 TYPES OF JOINTS FOR CONCRETE LININGS . 04/03/2015.MWB contracts [m Length of site cast tunnel linings (2) No. 6 LENGTHS AND EXCAVATED VOLUMES OF TUNNELS CONSTRUCTED WITH EXPANDED LININGS DURING FIVE-YEAR PERIODS . 195014 195519 196014 196519 197014 Year 195014 195519 196014 196519 1970/4 Year Don-reg Wedge Block .under licence LTE Running Tunnels [7 RoadIRail Tunnels Fig.Licensed copy from CIS: URS. of schemes under construction Wedge Block . URS Infrastructure. Uncontrolled Copy. 1970 1971 1972 1973 1974 1975 1976 Year Fig. 04/03/2015. Uncontrolled Copy.Licensed copy from CIS: URS. URS Infrastructure. 7 ANNUAL LENGTHS OF TUNNEL CONSTRUCTED WITH EXPANDED LININGS 1970-76 . Uncontrolled Copy. 04/03/2015. if required Minimum cover t o / steel arches 150mm \ Cast in-situ --. 8 TYPICAL SECTION OF A CAST I N S I T U CONCRETE TUNNEL .Licensed copy from CIS: URS. Excavated support. URS Infrastructure.--- ---I-- Invert slab (this may be circular) Fig. 9 G R O U N D M O V E M E N T S TRANSVERSE T O TUNNEL CENTRELINE . 04/03/2015. Heathrow Cargo tunnel43 I I I I 1 2 3 4 Distance from periphery of tunnel (m) (a) Ground movements at varying distances from tunnel at axis level Netherton Road d d - - 4 3 2 1 0 0 1 1 1 1 1 2 3 4 5 Distance from shield (rn) (b) Ground movements at approximately 1.5m from tunnel at axis level Fig. Uncontrolled Copy.Victoria1 Line ~ r i x t o n 7 7 Victoria Line Netherton Road24 0 Fleet Line Green park79 Fleet Line Regents park81 Licensed copy from CIS: URS. URS Infrastructure. 00 20.00 19.00 18. Uncontrolled Copy.00 16.Licensed copy from CIS: URS. - Axial movement - Radial movement 0.00 17.00 24.00 21. URS Infrastructure.00 Time (hours) (c) Horizontal ground movement with time at Netherton Road (4m external diameter) Fig 9 (cont) GROUND MOVEMENTS TRANSVERSE TO TUNNEL CENTRELINE .00 23.00 22.45m from tunnel Radial movement 2m from tunnel 0 15. 04/03/2015. ~ r i x t o n 7 7 '\ '/4 Centre of face 3/4 Ty neside84 Hebburn \ Periphery Position along axis (b) Domed shape of face movement F i g 10 A X I A L MOVEMENT TOWARDS THE FACE . Shield 8 7 6 5 4 3 2 1 0 Distance ahead of hood (m) (a) LTE E .Axial movement towards face 4 . URS Infrastructure.Victoria Line.\ "\'\J \ '\)/ / / / Periphery LTE . Brixton . 04/03/2015.u Licensed copy from CIS: URS. Uncontrolled Copy. / : / / // ' --. 04/03/2015.25 and 4 for the tunnels considered in Table 10 Tunnel (b) Typical profile of ground movement at surface and at depth Surface Crown Units of movement (c) Typical development of vertical movement with depth Fig 11 PROFILES OF VERTICAL GROUND MOVEMENTS . URS Infrastructure.Position of face \ ?. \\ \ \\ Licensed copy from CIS: URS.'\ Settleme \i \b \I.. \ I (a) Note The percentage of the total movement which occurs before the face passes the point of obsevation varies between 10 and 70%with different strata Surface \ \ - \A' / -at depth Possible heave in over consolidated clays 0/ -- 0- -c above crown Typical ground movements with depth on centreline of tunnel \ 0 \ +-4 0 Profile a t depth Note The ratio of maximum movement above the crown t o that at the surface varies between 1. Uncontrolled Copy.. URS Infrastructure. 04/03/2015.5) Heathrow Cargo tunnel43 (Dld .7) Licensed copy from CIS: URS. 81 Regents Park (Dld = 5) - T--81 Regents Park (Dld .0.5) I I 1 I I I 1 I 1 - 8) I Vertical distance above tunnel (m) (a) Ground movements on vertical section through tunnel centreline Distance from face (m) 20 15 10 5 Face5 10 15 20 I - - 2.9m from crown Ground movements for Heathrow Cargo tunnel (b) Time (days) 15 10 I I 5 0 5 10 15 1.D .External diameter of tunnel Green park79 (Dld = 7. Uncontrolled Copy.5m below surface 7rn below surface 5m below surface (c) Ground movements at LTE running tunnel at New Cross Fig.Depth to tunnel axis d .8m from crown 0.~ e b b u r n 8 4(Dld = 3. 12 MEASURED VERTICAL GROUND MOVEMENTS . water table - Sands below w-ater table I (a) I I I I I I Relationship of width of trough to depth of tunnel (after Peck 74) I Tail passes point of observation Face passes point of observation (b) Typical settlement curve (see Table 10) Fig. Uncontrolled Copy. URS Infrastructure. 04/03/2015.R .Depth to axis i . 13 SURFACE SETTLEMENT ABOVE A TUNNEL .Radius of tunnel D .Distance of point of maximum curvature from centre line - Licensed copy from CIS: URS. URS Infrastructure.Licensed copy from CIS: URS. 13 (cont) SURFACE SETTLEMENT ABOVE A TUNNEL . 1 2 Rate of progress (c) Ground movement with rate of progress Fig. Uncontrolled Copy. 04/03/2015. Uncontrolled Copy. 04/03/2015.Licensed copy from CIS: URS. URS Infrastructure. 1s t tunnel 2nd tunnel Fig. 14 TYPICAL SURFACE SETTLEMENT ABOVE TWO TUNNELS . 04/03/2015. URS Infrastructure. Uncontrolled Copy.Licensed copy from CIS: URS. 15 POSSIBLE SURFACE SETTLEMENT ABOVE PIPE JACKING TUNNEL . Normal typical section o f curve Possible additional settlement due t o drag C u t t i n g edge passes point o f o b s e r v a t i o n Fig. Jointed rock. 16 INFLUENCE OF ROCK CONDITION AND EXCAVATION DISTURBANCE ON GROUKD REACTION CURVE FOR ROCK TUNNELS (AFTER DEERE ET A L ) ~ . disturbed by excavation (incompetent) 1. d Radial deformation for stability of unlined in massive undisturbed rock 3. undisturbed by excavation (competent) Licensed copy from CIS: URS. 04/03/2015.Massive rock. URS Infrastructure. a b e Support yields before stabilising opening 4. Uncontrolled Copy. B .A . ab and ac Properly designed support 2. a f Support too flexible f a Total radial deformation Fig. Segments removed over width of opening and adjacent rings Lintel beams and jamb segments inserted (a) Portal frame opening with special lintel beams and jamb segments Special steel segmetns built into ring connected with friction grip bolts or with (b) Top and bottom lintel beam opening with load transferred t o adjacent standard rings Fig. 17 OPENINGS I N PERFORMED LININGS .Licensed copy from CIS: URS. Uncontrolled Copy. URS Infrastructure. 04/03/2015. . .Licensed copy from CIS: URS.. ... Shear pins thus formed with dry packed concrete 10 No. 04/03/2015. Jacking space filled with dry packed concrete . Uncontrolled Copy. segments from each of two rings removea a t opening ... special precast segments with preformed holes for shear pins RADIAL ELEVATION OF REFUGE Showing arrangement of segments Fig 18 SHEAR PIN OPENING I N EXPANDED CONCRETE LININGS ... ..% . Precast concrete lining. segments removed at opening 3 No.. URS Infrastructure..61m wide Shear pinithus formed with dry packed concrete SECTION OF TUNNEL AT REFUGE \ 10 No.... .. special precast segments with preformed holes for shear pins 6 No. 0. .. / (a) Face caulking for cast iron or concrete lining (b) Back of the joint caulking for cast iron lining Padding if required ___4\__ Caul king material ..Caulking material Licensed copy from CIS: URS.Face caulking Block joint for cast iron lining (c) Back of the joint caulkingT Gel grummet Nut Washer Gel grummet (prior t o tightening the bolt) Washer Oyster grummer compressed in bolt hole (e) Cross section through oyster grummet Oyster grummet tightened by bolt F i g 19 CAULKING OF TUNNEL LININGS . Uncontrolled Copy. 04/03/2015. URS Infrastructure. .'"- - .Licensed copy from CIS: URS.--Oa--'m- 1 1 I I I I I 150 300 450 600 7 50 900 1050 Length of drive (m) \ Fig. URS Infrastructure.- / * / ** h A v e rmachine. with cast iron lining General range for hand shield. Uncontrolled Copy Average for Roadheader machine Expanded concrete lining . 04/03/2015. bolted cast iron lining neral range for bolted cast n lining without a shield - 0 L I - / * / * - 0 'I / *- - * rd. 20 MAXIMUM SUSTAINED PROGRESS FOR LTE RUNNING TUNNELS .* \. I I 1200 1350 1500 .. a g efor Expanded full face 0. Hand shield Expanded concrete lining /- / * / * 4 - / /* 0 0 I' Isolated point for hand shield. linings * ' . 21 MAXIMUM SUSTAINED RATES OF PROGRESS FOR MACHINE DRIVES FOR LTE RUNNING TUNNELS . Full face machines Expanded concrete linings A Expanded cast iron linings 0 60% . URS Infrastructure. Uncontrolled Copy.40% bolted cast iron linings Roadheader machines Expanded concrete linings Fig.70% expanded concrete and cast iron linings 30% . 04/03/2015.Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy A Upper limit - - - Lower limit Spread of percentages for 40 drives for LTE running tunnels - I Length of drive (m) Fig.Licensed copy from CIS: URS. 04/03/2015. 22 PLOT OF RATIO OF RATES OF PROGRESS I I I I I Maximum sustained rate of progress (mlweeks) . Uncontrolled Copy.20.s -- 0 m P -- w + 0) c 0) z 0" 0 181) r --8 0) 7 . 04/03/2015.4 1841 0) zuc 0) Note Figures in brackets are the percentage cost of the tunnel structure t o the cost of the completed Tunnel 0) 17.4 1851 I Z I yO e Compressed air Cast iron Subaqueous Working condition Free air Concrete zzd1 zt: Subaqueous Concrete Fzd1 2 ~ ~ ~ 1 Underground Fig.1 4. URS Infrastructure.0 I781 + It L Licensed copy from CIS: URS. 6 15.+ . $ g e :' =8 E r 2.- O - Y > $ W 5.3 161.g > 10.-0 .8 9 .4 1861 I F i G F I I I Z m w O l " B I Z E 0) - -? 0 P0 3. 23 COSTS O F ROAD TUNNELS A T 1976 P R I C E S ~ ~ ~ Lining type Situation .4 I811 E 0) z' -2 - P C U .5 1711 7. 24 COSTS OF ROAD TUNNELS AT TIME OF CONSTRUCTION^^^ .Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. proportion of total cost (48%) d 1960 Year Fig. - (70%) t 1 (59%) I ( ) Figures in parenthesis indicate approximate I. Uncontrolled Copy. Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. Internal diameter of tunnel (m) Fis 25 RANGE OF COSTS OF TUNNELS WITH PRECAST CONCRETE LININGS . Uncontrolled Copy. 0. PREC-AST REINFORCED CONCRETE BOLTED LINING (After ~ c ~ e a n ) 2 8 .I I 7 Licensed copy from CIS: URS.61111 WIDE. 04/03/2015. 26 TYPICAL PRODUCTION COST OF 2. Uncontrolled Copy.45111 RING. 7 Construction - Production costs 0 1952 I I I 1 I 1956 1960 1964 1968 1972 1976 Year Fig. URS Infrastructure. URS Infrastructure. 27 TOTAL ANNUAL LENGTH OF TUNNELS AND SHAFTS. 1970-1976 1970 197 1 1972 1973 1974 1975 1976 Year Fig. 04/03/2015.Type of lining 1 Cast iron lnsitu concrete or unlined Expanded concrete Bolted and smooth bore concrete Licensed copy from CIS: URS. Uncontrolled Copy. 28 LENGTH OF EACH TYPE OF LINING AS A PERCENTAGE OF THE TOTAL LENGTH 1970-1976 . Site cast (% of all precast concrete segments in brackets) 1970 1971 1972 1973 1974 1975 1976 Year Fig. Uncontrolled Copy.Type of lining (% in brackets) Cast iron lnsitu concrete or unlined Expanded concrete Pre-cast concrete road tunnels Licensed copy from CIS: URS. 04/03/2015. Bolted and smooth bore concrete 1970 1971 1972. 29 TOTAL VOLUME OF EXCAVATION OF TUNNELS AND SHAFTS 1970-1976 1970 1971 1972 1973 1974 1975 1976 Year Fig 30 VOLUME OF TUNNEL I N EACH TYPE OF LINING AS A PERCENTAGE OF THE TOTAL VOLUME 1970-1976 . 1973 1974 1975 1976 Year Fig. URS Infrastructure. Uncontrolled Copy. 31 CUMULATIVE PERCENTAGE O F TOTAL LENGTH FOR PRECAST CONCRETE TUNNEL LININGS . 1 2 3 4 5 6 7 Internal diameter (m) Fig. URS Infrastructure. 04/03/2015.Licensed copy from CIS: URS. Uncontrolled Copy. Four segment ring Joint perpendicular to tunnel Spiral joint Fig 32 FOUR-SEGMENT L I N I N G S ~ ~ ~ . URS Infrastructure. 04/03/2015.Licensed copy from CIS: URS. URS Infrastructure. 33 DETAIL OF CAST IRON LINING FOR ELBE TUNNEL . Uncontrolled Copy. Groove for sealing strip rp 1. 04/03/2015.1 Cross-section 0 I of tubbing Longitudinal section of a tubbing Fig.Licensed copy from CIS: URS. 6 0.8 76.Licensed copy from CIS: URS.4 Cross-section thickness (in) Fig 34 EFFECT ON SECTION THICKNESS O F GREY 1 ~ 0 ~ 1 4 6 177.4 0.24 11 19.2 101.6 127.2 in bar) Cross-section thickness (rnm) 50. 04/03/2015. URS Infrastructure.05 25. Uncontrolled Copy.0 152.8 . 15.75 (Equivalent to 1. 8mm thick // Ring 0.2mm thick Circumferential flange 20. bolts Fig 35 TOWER SUBWAY TUNNEL LINING^^ . URS Infrastructure.46m wide Longitudinal flange 22. I / Skin 22.Licensed copy from CIS: URS.6mm to 23.8mm thick 19mm dia. Uncontrolled Copy.2mm to 23. 04/03/2015. URS Infrastructure. 04/03/2015. Cross-section through tunnel Cross section through segment Fig.Licensed copy from CIS: URS. Uncontrolled Copy. 36 STUBDEN RESERVOIR TUNNEL LINING^^ . 37 CHANNEL TUNNEL BEAUMONT TUNNEL LINING^^ . URS Infrastructure. Stiffener and lifting hole at centre \ Fig.Licensed copy from CIS: URS. Uncontrolled Copy. 04/03/2015. 8mm Circumferential joint F i e 38 LTE CITY AND SOUTH LONDON RAILWAY LINING^^ .Licensed copy from CIS: URS. Uncontrolled Copy. Internal diameter 3.2m Cros~sectionthrough tunnel Soft wood packing ' / Longitudinal joints 31. I m or 3. URS Infrastructure.8mm or 23. 04/03/2015. Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy. 39 MODIFICATIONS TO THE LTE CITY AND SOUTH LONDON RAILWAY LINING (1922-1924) .38) Fig. 04/03/2015. Old tunnel profile New tunnel profile \ \ A Additional castings to Same patterns B Key casting 71 Old key- C Re-used segments (see Fig. Circumferential joint Longitudinal joint Detail of key Fig. 40 VYRNWY TUNNEL LINING^^ . 04/03/2015. URS Infrastructure.Licensed copy from CIS: URS. Uncontrolled Copy. URS Infrastructure.4mm diam. Uncontrolled Copy. 04/03/2015.8m high Skin 25. 41 EDINBURGH M A I N DRAINAGE LINING^^ . Fig. Internal profile 2.Licensed copy from CIS: URS.4mm thick Bolts 25.18m wide by 2. URS Infrastructure. 42 BLACKWALL T U N N E L ~ 1 ~ 1 ~ ~ 1 6 . 04/03/2015. Uncontrolled Copy.Licensed copy from CIS: URS. Longitudinal joints Circumferential joints Key segment Detail of heavy lining Longitudinal joint Circumferential joints Key segment Detail of light lining Fig. Caulking groove rust caulked deal Cement caulking in clay Circumferential joint Fig. URS Infrastructure.Licensed copy from CIS: URS. Uncontrolled Copy. 43 L T E WATERLOO A N D C I T Y RAILWAY LINING^^ . Caulking groove Detail of joint in clay Detail of joint in waterbearing strata Longitudinal joint - In waterbearing ground 19mrn rubber ring positioned at back of joint. 04/03/2015. 04/03/2015.d. Uncontrolled Copy.1 Fig.56111 i. URS Infrastructure. Longitudinal joint Circumferentialjoint Detail of running tunnel lining (3.Licensed copy from CIS: URS. 44 LTE CENTRAL LONDON RAILWAY LINING^^ . 04/03/2015. Fig. 45 THE GREAT NORTHERN A N D CITY RAILWAY LINING^^ . URS Infrastructure.Licensed copy from CIS: URS. Uncontrolled Copy. 34. 04/03/2015. 46 L T E BAKER STREET AND WATERLOO R A I L W A Y LINING^^^ Pine .Rust b Machined face Fig. Uncontrolled Copy.Rust Profile o f caulking groove . URS Infrastructure.Licensed copy from CIS: URS.9mm . 04/03/2015. Uncontrolled Copy. URS Infrastructure. 47 G R E E N W I C H F O O T W A Y T U N N E L LINING^^ .Licensed copy from CIS: URS. Section through segment Lead washers Detail of key Fig. 48 ROTHERHITHE ROAD TUNNEL LINING . 04/03/2015.Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy. Circumferential joints Note: All dimensions in millimetres Fig. Wrought iron dished washers with bituminous washers underneath Circumferential joint Radial joint Note: All dimensions in millimetres Fig 49 MERSEY QUEENSWAY TUNNEL ~ 1 ~ 1 ~ ~ 1 5 4 . 04/03/2015. URS Infrastructure.Licensed copy from CIS: URS. Uncontrolled Copy. 04/03/2015. 50 DARTFORD TUNNEL AND BLACKWALL TUNNEL LINING^^^ .1 Caulking grooves to be machined out of the solid Licensed copy from CIS: URS.1 'Machined faces Longitudinal joint Note: All dimensions in millimetres Circumferentialjoint Fig. Uncontrolled Copy. URS Infrastructure. 38.1 38. Uncontrolled Copy.5 x 190.4 deep machined from solid Licensed copy from CIS: URS. 5 1 C L Y D E TUNNEL LINING^^^ .4 deep. 5 x 6. grummets and standard washers Circumferential joint Caulking groove. . 25.8wide feather Machined faces Note: All dimensions in millimetres Longitudinal joint Fig. URS Infrastructure.5 bolts. machined from solid . 25.Caulking groove.1 drainage slot 44. 04/03/2015. 4 Caulking grooves to be Machined facesf Longitudinal joint Fig. URS Infrastructure. Uncontrolled Copy.Licensed copy from CIS: URS. 04/03/2015. Circumferential joint 6. 52 TYNE TUNNEL LINING Note: All dimensions in millimetres . Black bolts M 42 x 190 1- 200 3 3' Machined faces Longitudinal joint Note: All dimensions in millimetres Circumferential joint Fig. URS Infrastructure. 04/03/2015. 53 MERSEY KINSGWAY TUNNEL L I N I N G ~ ~ O . Uncontrolled Copy.44 44 Licensed copy from CIS: URS. packing 1 I Circumferential joint Caulking groove to be achined from the solid Countersunktor grummet (6~ 4 5 0 ) Note: All dimensions in millimetres / Machined faces Longitudinal joint Fig. 1 M24 black washfr fi/& Creosoted deal . Uncontrolled Copy. 04/03/2015. 54 L T E FLEET L I N E R U N N I N G T U N N E L L I N I N G .Licensed copy from CIS: URS. URS Infrastructure. Licensed copy from CIS: URS. Uncontrolled Copy. 04/03/2015. URS Infrastructure. _r tI9. mrn Fig 55 L T E V I C T O R I A L I N E EXPERIMENTAL SPHEROIDAL GRAPHITE TUNNEL L I N I N G . 04/03/2015.Licensed copy from CIS: URS. Uncontrolled Copy. LONGITUDINAL JOINT I- 120 Note: All dimensions in millimetres CIRCUMFERENTIAL JOINT Fig. URS Infrastructure. 56 SPHEROIDAL GRAPHITE LINING FOR CHANNEL TUNNEL STAGE 2 . 5537 dia.Licensed copy from CIS: URS. URS Infrastructure. Section A-A Upper flange of each closure ring t o have a thickening of 16mm on both sides Section C-C Back view of segment Ten segments per tubbing ring Section D-D ( w i t h closure ring details Cementation hole in middle of segment t o be drilled only in 5 segments of every second ring Section B-B (Every fourth ring) All segments of every fourth ring to have an oblique hole in middle of lower flange. 04/03/2015. Note: All dimensions in millimetres Fig. Remainder to have rib similar t o upper flange. Uncontrolled Copy. 57 SPHEROIDAL GRAPHITE LINING FOR BOULBY POTASH SHAFT . - 5690 di a. URS Infrastructure. Note: All dimensions in rnillimetres Fig. 04/03/2015. 58 SPHEROIDAL GRAPHITE LINING FOR WASHINGTON M E T R O .Licensed copy from CIS: URS. Uncontrolled Copy. S. Uncontrolled Copy. Detail of Dungeness'A' tunnel lining 34. URS Infrastructure.61 m Note: All dimensions in millimetres Detail of Dungeness 'B' tunnel lining Fig 59 DUNGENESS T U N N E L L I N I N G . bolt holes 4 fl Equal Taper plug 31.pipe thread ~1 Equal c 0. ax.7 Licensed copy from CIS: URS. B.75 dia.9 dia. 04/03/2015. 04/03/2015. 60 AMSTERDAM METRO. URS Infrastructure. hole I Details of longitudinal joint Note: All dimensions in millimetres Section A-A Fig. x 110 long bolt in 34 dia. Uncontrolled Copy.Licensed copy from CIS: URS. II Key segment skin Corss section of completed ring 5x5 chamfers t o Machined faces 30 dia. PROPOSED TUNNEL LINING . EXPANDED GREY I R O N LININGIS . 61 L T E V I C T O R I A LINE . URS Infrastructure. L A Section A-A Section through tunnel Front elevation of jacking pocket Section C-C Section B-B Detail of jacking pocket Fig.Licensed copy from CIS: URS. Uncontrolled Copy. 04/03/2015. 04/03/2015. URS Infrastructure.Licensed copy from CIS: URS.71111 internal diameter bolted lining I lT?!37 i3 as detail B 4 Detail C 0 Detail B b) Expanded bolted lining Fis 62 LTE EXPANDED BOLTED GREY IRON LINING 22 . a) Standard 3. Uncontrolled Copy. 28.6mm dia. B.S.W. bolt i n 47.6mm dia. hole 48-47.6mm dia. bolt holes equally spaced on a pitch circle 6.8m dia. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. rA 40 Circumferential joint Section D-D radial joint LA 31.8 dia. Cross section through tunnel lining 4% Elevation at jack recess Section 6-6 Section E-E Note: All dimensions in m~llimetres Section C-C F i g 63 L T E EXPANDED STEEL LINING FOR VICTORIA LINE - OXFORD CIRCUS STATION^^ Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. General plan of tunnels at King's Cross Fleet sewer Concourse curve Hotel curve Southbound Northbound Victoria Line - Westbound Piccadilly line Southbound Northern Line a Northbound Northern Line Cross section at King's Cross C Six 44.5mm dia. HT BSW bolts in 47.6mm dia. holes at each radial ioint k - Fi Wedging space Three 28.6mm dia. BSW bolts in 34.9mm dia. holes at each radial joint 4828.6mm dia. bolts in 47.6mm holes on PCD 6.80m Details of lining Fig. 64 PLAN OF LTE STATION AT KING'S CROSS AND DETAILS OF EXPANDED STEEL LINING FOR VICTORIA LINE STATION^^ TB - -- --------------- Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Bolts are staggered t o provide more strength I I Plan Covering length 0.96mm 1.12m, 1.28m Elevation Minimum radius 0.61m 7 gauge and lighter 5 gauge 0.76m 3 gauge 0.76m Section A-A 69.8mm Varies Section C C Section B-B F i g 65 D E T A I L S O F ARMCO LINER P L A T E S ~ ~ Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Grout hole A-A (406mm L.P.) C-C (406-610mm L.P.) B-B 406-610mm L.P.) fi ~---%--J --- ----+_-+-_ I l l Note: All dimensions in millimetres Fig. 66 DETAILS OF COMMERCIAL HYDRAULICS LINER P L A T E S * ~ Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Q Timber master 0 Concrete master 8 I -+= Concrete master used t o manufacture die moulds I Die moulds 8 6 I Production moulds Die moulds used to manufacture required number of production moulds & Segments Fig. 67 DIAGRAMMATIC LAYOUT OF CASTING CONCRETE M O U L D S ~ ~ Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Cross-section through tunnel 5.4mm cross wires 8.3mm dia. / \ $ I Radius 0.81m \ 6.4mm M.S. liner plate Caulking groove Details of reinforcement Fig. 69 MERSEY KINGSWAY GROUTED SMOOTH BORE CONCRETE LINING^^ *' . 70 LTE VICTORIA LINE M O T 1 H A Y AND ANDERSON EXPANDED CONCRETE L I N I N G ". 'All reinforcement 1. Uncontrolled Copy.Licensed copy from CIS: URS.6mm rad. nominal Radial joint Detail of jacking pocket showing precast filling wncrete Detail of jacking pocket showing packer Reinforcement shown is for all female joints Section C C Fig. 04/03/2015. LA Section B-B LB Section A-A Note. URS Infrastructure. stirrups 16 dia.---.Licensed copy from CIS: URS. 71 L T E FLEET LINE EXPANDED CONCRETE LINING . URS Infrastructure.S. H. bars 2 No. BI . a ----. 04/03/2015.= Note.. Uncontrolled Copy... 16 dia... 1 20 . short bars t o form cage I Section A-A Elevation II.20 cover 20 cover I 2 No... All dimensions are in millimetres ----- Plan on 6-6 Segment type A Fig.--------------------= ....Y.. R (from outside o f lining) Plan Detail o f lining Transverse steel 8. Uncontrolled Copy. 04/03/2015. Section C-C \ Stirrups and l i n k bars 8 m m dia. Grouting holes Type'B'L type'^'^ Elevation o f segment (from outside o f lining) Pad Segment Elevation o f ring Lifting bar Detail a t Taper key detail (Section along m i d surface plane) ')(' Elevation o f segment Elevation of segment (from outside o f lining) Type 'C'. Circumferential steel 1 0 and 12mm dia.Segment Type 'C'L Key Segment Type 'C' R Pad Chamfer o f leading edge o f wedge Licensed copy from CIS: URS. URS Infrastructure. 10 and 1 2 m m dia. Detail o f invert segment reinforcement Fig. 72 CHANNEL T U N N E L STAGE 2 EXPANDED G R O U T E D CONCRETE L I N I N G . Uncontrolled Copy.Licensed copy from CIS: URS. 04/03/2015. Reinforcing bar reinforcing bar Cross section Fig 73 McALPlNE GROUTED SMOOTH BORE LINING FOR DERBY SEWER CONTRACT . URS Infrastructure. URS Infrastructure. Circumferential bolt coupled a t each joint with toggle -v Fig 74 CHARCON UNIVERSAL GROUTED SMOOTH BORE CONCRETE LINING^^ . 04/03/2015.Licensed copy from CIS: URS. Uncontrolled Copy. Licensed copy from CIS: URS. URS Infrastructure.. . 75 ORIGINAL DESIGN FOR LTE BOLTED CONCRETE LINING FOR CENTRAL LINE EXTENSION TO ILFORD24 . Cross section through tunnel " Allowanc Allowances for / 3.--------x"A .5Im Section A-A B Fig..2mm b bituminous ~~um~nous packing in f longitudinal joints Longitudinal joint I -I\ -I\ a u 1 11- / I 4' ...!A dLc:/@.-stirrup? d L. II " Section B-B L-. Uncontrolled Copy.q @ stirrup? -----_Y .- 0. 04/03/2015. Licensed copy from CIS: URS. Uncontrolled Copy. Cross section Detail of longitudinal joint at key segment Detail of circumferential joint F i g 76 STANDARD BOLTED CONCRETE LINING^^ . 04/03/2015. URS Infrastructure. Uncontrolled Copy. Six segmentslring Fig 77 BUCHAN SMOOTHVERT CONCRETE LINING^^ . URS Infrastructure.Licensed copy from CIS: URS. 04/03/2015. 04/03/2015. URS Infrastructure. Section Elevation Detail of segment Exploded section Elevation Fig 78 DON-SEG EXPANDED CONCRETE LINING . Uncontrolled Copy.Licensed copy from CIS: URS. Licensed copy from CIS: URS. 04/03/2015. URS Infrastructure. Fig 79 WEDGE BLOCK EXPANDED CONCRETE LINING^^ . Uncontrolled Copy. Trailing \ face Section A-A Cross section through tunnel Details o f standard Voussoir block .I Precast standard voussoir blocks Eleven at i40 = 1540 76mm dia.3% Portland cement concrete Details of invert unit Fig. Invert units cast i n 1.5mm dia. 04/03/2015. Uncontrolled Copy. stirrups Elevation Note: All dimensions in metres Note. URS Infrastructure.76 . lifting hole I %fj/ Licensed copy from CIS: URS. 80 BR GREENWOOD TO POTTERS BAR TUNNELS EXPANDED CONCRETE LINING^^ . 1 60 Jacking space wan r-0. Licensed copy from CIS: URS. Uncontrolled Copy. 04/03/2015.21 . URS Infrastructure. Cross section segment details Fig 81 L T E VICTORIA L I N E EXPERIMENTAL LENGTH HALCROW EXPANDED CONCRETE LINING 19. Licensed copy from CIS: URS. 82 LTE VICTORIA LINE HALCROW EXPANDED CONCRETE LININGIS . between segments 12. Uncontrolled Copy. 04/03/2015.7 chamfers Detail of joint between rings Drainage recess Note: All dimensions in millimetres except where shown Fig. URS Infrastructure.7 x 12. URS Infrastructure. 04/03/2015. I Section A-A I Elevation B-B Side elevation F r o n t elevation Fig. 83 LTE VICTORIA LINE HALCROW JACKING ME . Uncontrolled Copy.Licensed copy from CIS: URS. Licensed copy from CIS: URS. Elevation Details o f segment reinforcement shown o n Fig. 04/03/2015. URS Infrastructure. Uncontrolled Copy. 84 LTE FLEET LINE EXPANDED CONCRETE LINING .71 Fig. URS Infrastructure.Licensed copy from CIS: URS. 84 ( a n t ) L T E FLEET L I N E EXPANDED CONCRETE LINING . Approximate edge distance 1 15 Detail of joint between segments (Except at wedging segments) 25 Detail of joint between rings Caulking groove Note. All dimensions are in millimetres Developed elevation of wedging segments Fig. Uncontrolled Copy. 04/03/2015. Uncontrolled Copy. Segment Mk. firstly between horns and secondly in recesses following removal of jacks .3 Jacking spaces packed with earth dry concrete in two stages after stressing. s C 5- 25. 0 c 4-I rad.4 x 25.Licensed copy from CIS: URS. 85 BAA HEATHROW CARGO TUNNEL EXPANDED CONCRETE LINING^^ . e.4 chamfers L_/ 607 305 7 3175 rad. Note: All dimensions in millimetres Three dimensional view of jacking space Fig. 04/03/2015. t Jacking recesses 3175 rad. I Segment Mk. URS Infrastructure. metres Caul king Slot - 0 100 200 Scale.Licensed copy from CIS: URS. 04/03/2015. Scale . URS Infrastructure. Uncontrolled Copy. 86 COLLIN'S EXPANDED CONCRETE LINING^^ .millimetres Fig. polyacctal pin Trailing edge of adjacent segment (b)Circumferential joint of Extratlex lining F i g 87 SPUN CONCRETE FLEXILOK AND EXTRAFLEX GROUTED SMOOTH BORE CONCRETE LININGS~~ .vation Rubberised bitumen strip In lateral end ircumferential joints Former ring fixing bolts Special screw bol for retaining steel former shoes tie rod rods former shoes v Details of joint and former ring (a) Flexilok lining Neoprene foam rubber seal 16mm thick 11 Leading edge of segment 19mm dia. Uncontrolled Copy. URS Infrastructure. 04/03/2015.Left hand crown segment crown segment Licensed copy from CIS: URS. segments End ele. Uncontrolled Copy.Licensed copy from CIS: URS. URS Infrastructure.1 boogie hole Cross section through lining Fig. 04/03/2015. 88 CHARCON RAPID GROUTED SMOOTH BORE CONCRETE LINING^^ . L A Section A-A Cross sectional plan Radiused channel Plastic tube / d istance piece 7 I Detail of segment A dia. 04/03/2015.. URS Infrastructure.Thickness varies for Licensed copy from CIS: URS. each diameter 4and -1 I Detail of joint below \Four stress relievers per segment Section through tunnel Detail of joint Fig. Uncontrolled Copy. 89 REES M I N I TUNNEL GROUTED SMOOTH BORE CONCRETE LINING- . .Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. Uncontrolled Copy. 5mm dia. 91 GIBRALTAR HILL TUNNEL CAST IN-SITU CONCRETE LINING^^ .Licensed copy from CIS: URS.458111 Reinforced concrete / mild steel sDacers Fig. Uncontrolled Copy & of Grout pipes a t 2 . 04/03/2015. h tunnels Steel svmmetric.4mm dia. URS Infrastructure.al 9. I 25. bars at 229mm crs . mild 76mm blinding layer / -16. URS Infrastructure. . 04/03/2015.Licensed copy from CIS: URS. Uncontrolled Copy. URS Infrastructure. 04/03/2015. Maximum width of excavation 9.Licensed copy from CIS: URS. Uncontrolled Copy. 93 BR WOODHEAD TUNNEL CAST I N S I T U CONCRETE LIN 1 ~ ~ 5 8 .3m \ Haunch drain _I Centre drain Fig. URS Infrastructure. 04/03/2015. Uncontrolled Copy. 94 BR HARECASTLE TUNNEL CAST IN-SITU CONCRETE LINING^^^ .Licensed copy from CIS: URS. Fig. Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. I n ~ Mohr h n O.D. Low pressure tunnels erate and breccia Machine shafts \ Access tunnel Loch Ness W.L.n 15.9m O.D. General plan NE access road Surge chamber access adit. Lower control w Access road Cooling waterchamber C~o.2 machine shaft Line of screen \ \ Extent of excavatid:d& in front of screens I)) \ X junction Main access tunnel High-pressure drainage tunnel portal \ 5.95m 'D' shaped low-pressure tunnel 2.29m 'D' shaped drainage tunnel ining wall - 0 9.15 Detail at high pressure end Fig 95 FOYERS SCHEME - LAYOUT loom Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. 2.74 x 3.05m steel arches Arch section 102mm x 102mm x 7kg Fis96 EAST BRISTOL SEWER TUNNEL CAST IN-SITU CONCRETE LINING^^^ Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Cross section of twin tunnels between Malago intake and Malago relief culvert I Note: All dimensions in metres 1.693 0.350 I 0.150 sub base 1 Tunnel section Malago to Pigeonhouse Fis 97 BRISTOL MALAGO SEWER TUNNELS CAST I N S I T U CONCRETE L I N I N G S ~ ~ Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. to arch 300mm 3 piece horseshoe steel arches with corrugated sheeters Fig 98 EDINBURGH OUTFALL SEWER TUNNEL CAST INSITU CONCRETE LINING Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Point anchor Point anchor Wood dowel Steel reinforcement Woodlsteel bar (a) Main types of reinforcement Resin bonded Mandrel type Expansion shell (b) Main types of anchorage Fig. 99 TYPES OF ROCK BOLTS Wedge and slot Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Joint Diameter of arch Diameter of arch Two-piece arch Three-piece arch Width ot base Width of base Two-piece arch Three-piece arch (a) Standard arch profiles Fig. 100 TYPES OF STEEL ARCHES (BRITISH STEEL CORPORATION) Crown length 3658 Licensed copy from CIS: URS, URS Infrastructure, 04/03/2015, Uncontrolled Copy. Strut holes available Two or three piece arch Extra splay-legged arch T w o- o r three piece arch Horse-shoe arch Three, four o r five piece Circular support Three o r five piece arch Double radius arch k 89 x 89 x 19.35 k g l m Note: A l l dimensions in millimetres T w o piece arch Refuge-hole arcn (b) Non standard arch profiles Fig. 100 (cont) TYPES OF STEEL ARCHES (BRITISH STEEL CORPORATION) Note: All dimensions in rnillirnetres (c) Arch sections Fig 100 (cont) TYPES OF STEEL ARCHES (BRITISH STEEL CORPORATION) . Uncontrolled Copy. 04/03/2015.Licensed copy from CIS: URS. URS Infrastructure. Bolt fixings if required Liner plates Spile lagging Steel sheeters Timber or concrete laggings between f langers Wedges Fig 101 TYPES OF LAGGING FOR STEEL A R C H E S ~ ~ . URS Infrastructure. Uncontrolled Copy.Licensed copy from CIS: URS. 04/03/2015. Licensed copy from CIS: URS. Uncontrolled Copy Bernold I Ground supeort concrete Temporary . 04/03/2015. URS Infrastructure.arch / I Bernold sheets / Primary lining concrete Longitudinal section after primary concreting Ground support concrete sheets Longitudinal struts I Typical cross section through tunnel Longitudinal section of ground support Fis 102 DETAILS OF THE BERNOLD SYSTEM^^ . Uncontrolled Copy.Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. Plate 1 BOLTED GREY IRON LINING FOR LTE . . URS Infrastructure. 04/03/2015.Licensed copy from CIS: URS. Uncontrolled Copy. 04/03/2015.Licensed copy from CIS: URS. . Uncontrolled Copy. URS Infrastructure. Plate 4 E X P A N D E D G R E Y I R O N L I N I N G .Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. Uncontrolled Copy. Plate 5 LTE PICCADILLY LINE EXTENSION T O HEATHROW EXPANDED FORM OF BOLTED GREY IRON L I N I N G . 04/03/2015. Uncontrolled Copy.Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy. URS Infrastructure. 04/03/2015.Licensed copy from CIS: URS. Plate 6 O P E N I N G W I T H F A B R I C A T E D STEEL SEGMEN-TS . 04/03/2015. . Uncontrolled Copy. URS Infrastructure.Licensed copy from CIS: URS. . 04/03/2015.Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy. . Uncontrolled Copy. URS Infrastructure.Licensed copy from CIS: URS. 04/03/2015. Licensed copy from CIS: URS. 04/03/2015. URS Infrastructure. Uncontrolled Copy. . URS Infrastructure.Licensed copy from CIS: URS. Uncontrolled Copy Plate 11 COMMERCIAL HYDRAULICS STEEL LINER PLATES . 04/03/2015. Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy Plate 12 TYPICAL CONCRETE MOULD FOR BOLTED CONCRETE LININGS . 04/03/2015. Uncontrolled Copy.Licensed copy from CIS: URS. 04/03/2015. URS Infrastructure. . .Licensed copy from CIS: URS. 04/03/2015. URS Infrastructure. Uncontrolled Copy. Uncontrolled Copy. URS Infrastructure. 04/03/2015. .Licensed copy from CIS: URS. Licensed copy from CIS: URS. . Uncontrolled Copy. 04/03/2015. URS Infrastructure. URS Infrastructure. .Licensed copy from CIS: URS. 04/03/2015. Uncontrolled Copy. Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy. Plate 18 DON-SEG E X P A N D E D CONCRETE L I N I N G '30 52357 74 . 04/03/2015. "\Ipy. Licensed copy from CIS: URS. . URS Infrastructure. Uncontrolled Copy. 04/03/2015. Licensed copy from CIS: URS. 04/03/2015. HALCROW EXPANDED CONCRETE LINING . Plate 20 L T E VICTORIA LINE. Uncontrolled Copy. URS Infrastructure. Uncontrolled Copy. . URS Infrastructure. 04/03/2015.Licensed copy from CIS: URS. Licensed copy from CIS: URS. 04/03/2015. . Uncontrolled Copy. URS Infrastructure. Uncontrolled Copy. Plate 23 BR GREENWOOD TO POTTERS BAR T U N N E L EXPANDED CONCRETE L I N I N G .Licensed copy from CIS: URS. 04/03/2015. URS Infrastructure. no. URS Infrastructure.Licensed copy from CIS: URS. B218b114 Plate 24 BAA HEATHROW AIRPORT CARGO TUNNEL EXPANDED CONCRETE LINING . Uncontrolled Copy Neg. 04/03/2015. . URS Infrastructure. 04/03/2015.Licensed copy from CIS: URS. Uncontrolled Copy. Licensed copy from CIS: URS. URS Infrastructure. 8391'75 Plate 26 SPUN C O N C R E T E F L E X I L O K G R O U T E D SMOOTH BORE CONCRETE L I N I N G . 04/03/2015. Neg. Uncontrolled Copy. no. Licensed copy from CIS: URS. 04/03/2015. no. Neg. URS Infrastructure. Uncontrolled Copy. 838175 Plate 27 SPUN CONCRETE EXTRAFLEX GROUTED SMOOTH BORE CONCRETE L I N I N G . Licensed copy from CIS: URS. . URS Infrastructure. Uncontrolled Copy. 04/03/2015. Uncontrolled Copy. no. URS Infrastructure.Licensed copy from CIS: URS. 04/03/2015. B519175 Plate 29 CHARCON UNIVERSAL GROUTED SMOOTH BORE CONCRETE LINING . Neg. no. 8244175 Plate 30 REES M I N I T U N N E L G R O U T E D SMOOTH BORE CONCRETE L I N I N G . Uncontrolled Copy. 04/03/2015. URS Infrastructure. Neg.Licensed copy from CIS: URS. 04/03/2015. Neg. B1293/74/4 Plate 31 McALPlNE GROUTED SMOOTH BORE CONCRETE L I N I N G . URS Infrastructure. Uncontrolled Copy. no.Licensed copy from CIS: URS. Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy. . 04/03/2015. Uncontrolled Copy. URS Infrastructure. 04/03/2015.Licensed copy from CIS: URS. . Licensed copy from CIS: URS. . Uncontrolled Copy. URS Infrastructure. 04/03/2015. 04/03/2015. Uncontrolled Copy.Licensed copy from CIS: URS. URS Infrastructure. . Licensed copy from CIS: URS. URS Infrastructure. Uncontrolled Copy. Plate 36 B I R M I N G H A M GREAT CHARLES STREET TUNNEL CAST IN-SITU CONCRETE L I N I N G . 04/03/2015. URS Infrastructure. Uncontrolled Copy. Plate 37 BR WOODHEAD TUNNEL. CAST IN-SITU CONCRETE L I N I N G . 04/03/2015.Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. Uncontrolled Copy. Plate 38 BR LIVERPOOL LOOP TUNNEL CAST IN-SITU CONCRETE AND SHOTCRETE LININGS .Licensed copy from CIS: URS. 04/03/2015. Uncontrolled Copy. URS Infrastructure.Licensed copy from CIS: URS. . URS Infrastructure. . 04/03/2015.Licensed copy from CIS: URS. Uncontrolled Copy. Uncontrolled Copy.Licensed copy from CIS: URS. 04/03/2015. URS Infrastructure. . 04/03/2015. Uncontrolled Copy.Licensed copy from CIS: URS. . URS Infrastructure. Uncontrolled Copy. 04/03/2015.Licensed copy from CIS: URS.' f . no. B456178 Plate 43 BERNOLD STEEL TEMPORARY GROUND SUPPORT . URS Infrastructure. " f f * . ' Neg. no. 04/03/2015. Neq. Uncontrolled Copy. URS Infrastructure. R 362/78121 A Plate 44 BRICK SECONDARY L I N I N G .Licensed copy from CIS: URS. Licensed copy from CIS: URS. Plate 45 SHUTTERING FOR CAST IN-SITU CONCRETE SECONDARY LINING . URS Infrastructure. 04/03/2015. Uncontrolled Copy. Uncontrolled Copy.Licensed copy from CIS: URS. . 04/03/2015. URS Infrastructure. 821 85174 Plate 47 THIN CEMENT MORTAR SECONDARY LINING . URS Infrastructure. Neg. Uncontrolled Copy.Licensed copy from CIS: URS. 04/03/2015. no. Uncontrolled Copy. . URS Infrastructure.Licensed copy from CIS: URS. 04/03/2015. Uncontrolled Copy.Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. Plate 49 STEEL SECONDARY L I N I N G . Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. . Uncontrolled Copy. URS Infrastructure.Licensed copy from CIS: URS. Uncontrolled Copy. . 04/03/2015. 04/03/2015. Uncontrolled Copy.Licensed copy from CIS: URS. Plate 52 R E S I N F E L T S E C O N D A R Y L I N I N G I N S M A L L D I A M E T E R PIPE . URS Infrastructure. Uncontrolled Copy. URS Infrastructure. - r I ma - Plate 53 EPOXY TAR SECONDARY LINING . 04/03/2015.Licensed copy from CIS: URS. Licensed copy from CIS: URS. URS Infrastructure. 04/03/2015. Uncontrolled Copy. . 100 8 . 04/03/2015. URS Infrastructure.Licensed copy from CIS: URS. (1320) Dd0536316 1. 7 8 H P L t d So'ton GI915 PRINTED IN E N G L A N D . Uncontrolled Copy. 04/03/2015. 1978 (Transport and Road Research Laboratory). broken down into different types of lining and tunnel usage.ABSTRACT Licensed copy from CIS: URS. Methods of waterproofing tunnels. This Report outlines the several methods used in the United Kingdom for lining tunnels and gives brief details of some of the more recent tunnels constructed with each form of lining. TRRL Supplementary Report 335: Crowthorne. TRRL Supplementary Report 335: Crowthorne. use of secondary linings and cost data are included. The different methods available for lining tunnels are discussed taking into account the tunnel usage and the ground conditions. Uncontrolled Copy. The instrumentation of tunnel linings and of ground movements during the construction of tunnels have been examined and the design methods are discussed. ISSN 0305-1 3 15 ABSTRACT A REVIEW OF TUNNEL LINING PRACTICE IN THE UNITED KINGDOM: R N Craig and A M MuirWood (Sir William Halcrow and Partners): Department of the Environment Department of Transport. Recommendations are given for research and development of tunnel linings. 1978 (Transport and Road Research Laboratory). The instrumentation of tunnel linings and of ground movements during the construction of tunnels have been examined and the design methods are discussed. Methods of waterproofing tunnels. use of secondary linings and cost data are included. URS Infrastructure. The approximate annual length and volume of tunnels constructed for the period 1970-76 are given. ISSN 0305-131 5 . The approximate annual length and volume of tunnels constructed for the period 1970-76 are given. This Report outlines the several methods used in the United Kingdom for lining tunnels and gives brief details of some of the more recent tunnels constructed with each form of lining. A REVIEW OF TUNNEL LINING PRACTICE IN THE UNITED KINGDOM: R N Craig and A M MuirWood (Sir William Halcrow and Parmers): Department of the Environment Department of Transport. The different methods available for lining tunnels are discussed taking into account the tunnel usage and the ground conditions. Recommendations are given for research and development of tunnel linings. broken down into different types of lining and tunnel usage.