REFERENCES Abu-Farsakh M Y and Voyiadjis G Z (1999). Computational model for the simulation of the shield tunnelling process in cohesive soils. International Journal for Numerical and Analytical Methods in Geomechanics, 23, pp.23-44. ACI (1989). Building code requirements for structural concrete (318-99) and commentary (318R-99), American Concrete Institute. Addenbrooke T I, Potts D M and Puzrin A M (1997). The influence of pre-failure soil stiffness on the numerical analysis of tunnel construction. Geotechnique 47, No. 3, pp.693-712. Anand S, Leong E C and Cheong H K (2001). The use of a Continuous Surface Wave Measurement System for in situ characterisation of soil. Proceedings of the International Conference on Insitu Measurement of Soil Properties and Case Histories, Bali, pp. 139-144. Augarde C E, Burd H J and Houlsby G T (1998). Some experiences of modelling tunnelling in soft ground using three-dimensional finite elements. Proceeding of 4th European Conference on Numerical Methods in Geotechnical Engineering, Udine, 14-16 October 1998, pp.603-612. Augarde C E and Burd H J (2001). Three-dimensional finite element analysis of lined tunnels. International Journal for Numerical and Analytical Methods in Geomechanics, 25, pp. 243-262. Bezuijen A and Schrier J V D (1994). The influence of a bored tunnel on pile foundations. CENTRIFUGE 94, Singapore. Leung, Lee & Tan (eds)., pp.681-686.

Bloodworth A G (2002). Three-dimensional analysis of tunnelling effects on structures to develop design methods, PhD thesis, University of Oxford. Bond A J and Jardine R J (1991). Effects of installing displacement piles in a high OCR clay. Geotechnique 41, No. 3, pp. 341-363. Bransby and Springman (1996). 3-D Finite element modelling of pile groups adjacent to surcharge loads. Computers and Geotechnics, Vol. 19, No. 4, pp.301-324. Broms B B (1979). Negative skin friction. Proceedings of 6th Asian Regional Conference on Soil Mechanics and Foundation Engineering, Singapore, Volume 2, pp.41-75. Broms B B and Pandey P C (1987). Influence of ground movements from tunnelling on adjacent piles and remedial measures. 5th International Geotechnical Seminar, Case Histories in Soft Clays, Singapore. Brown D A and Shie C F (1990). Three dimensional finite element model of laterally loaded piles. Computers and Geotechnics, pp.59-79. BS5930 (1981). Code of Practice for Site Investigations. British Standards Institution, London. BS8004 (1986). Code of practice for foundations. British Standards Institution, London.

323

BS8110 (1997). Structure use of concrete. Part 1: Code of practice for design and construction. British Standards Institution, London. Buhan P D and Salencon J (1987). Analyse de la stabite des ouvrages en sols renforces par une methode d’homogeneisation. Revue Francasise de Geotechnique, No. 41, pp.29-43. Burland J B, Standing J R and Jardine F M (2002). Building response to tunnelling. Case studies from construction of the Jubilee Line Extension, London. Thomas Telford, London. Chandler R J and Martins J P (1982). An experimental study of skin friction around piles in clay. Geotechnique 32, No. 2, pp. 119-132. Chapman DN, Rogers C D F and Hunt D V L (2004). Predicting the settlements above twin tunnels constructed in soft ground. Proceedings of the 30th ITA-AITES World Tunnel Congress, 22-27 May 2004, Singapore. Chen C Y and Martin G R (2002). Soil-structure interaction for landslide stabilizing piles. Computer and Geotechnics, Vol. 29, pp.363-386. Chen L T and Poulos H G (1997). Effects of tunneling on piled foundations. Computer Methods and Advances in Geomechanics, Yuan (eds), pp.2183-2188. Chen L T, Poulos H G and Loganathan N (1999). Pile responses caused by tunneling. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 125(3), pp.207-215. Chen et al. (2000). Approximate design charts for piles adjacent to tunneling operations. Proceeding of GEOENG 2000, Melbourne. Cheng C Y, Dasari G R, Leung C F, Chow Y K and Rosser H B (2004). 3D numerical study of tunnel-soil-pile interaction. 30th AITES-ITA World Tunnel Congress, Singapore. Cheung Y K, Lee P K K and Zhao W B (1991). Elastoplastic analysis of soil-pile interaction. Computers and Geotechnics 12, pp.115-132. Chow Y K, Lim C H and Karunaratne G P (1996). Numerical modeling of negative skin friction on pile groups. Computer and Geotechnics, 18, No. 3, pp.201-224. Clarke B G (1995). Pressuremeter in geotechnical design (1st edition). Blackie Academic & Professional. Comodromos E M, Anagnostopoulos C T and Georgiadis M K (2003). Numerical assessment of axial pile group response based on load tests. Computer and Geotechnics, Vol. 30 (6), pp.505-516. Coutts D R and Wang J (2000). Monitoring of reinforced concrete piles under horizontal and vertical loads due to tunneling. Tunnels and Underground Structures, Zhao, Shirlaw & Khrisnan (eds), Singapore, pp. 541-546. Dames and Moore (1983). Mass rapid transit system, Singapore: Detailed geotechnical study. Interpretative Report, Provisional Mass Rapid Transit Authority, Singapore.

324

Dasari G R (1996). Modelling the variation of soil stiffness during sequential construction. PhD thesis, Cambridge University. Deane A P and Bassett R H (1995). The Heathrow trial tunnel. Proceeding of Institution of Civil Engineering: Geotechnical Engineering, 113, pp.144-156. Dias D, Kastner R & Maghazi M (2000). Three-dimensional simulation of slurry shield tunneling, Geotechnical Aspects of Underground Construction in Soft Ground, Kusakabe, Fujita & Miyazaki (eds), pp. 351-356. Ding W Q, Yue Z Q, Tham L G, Zhu H H, Lee C F and Hashimoto T (2004). Analysis of shield tunnel. Int’ Journal for Numerical and Analytical Methods in Geomechanics, 28, pp.57-91. Eisenstein Z, El-Nahhas F and Thomson S (1981). Strain field around a tunnel in stiff soil. 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm. Ellis E A and Springman S M (2001). Full-height piled bridge abutments constructed on soft clay. Geotechnique 51, No. 1, pp. 3-14. Ellis E A and Springman S M (2001). Modelling of soil-structure interaction for a piled bridge abutment in plane strain FEM analyses. Computer and Geotechnics 28, pp.79-98 Fellenius B H (1989). Tangent modulus of piles determined from strain data. Foundation Engineering: Current principles and practices, Vol. 1 (F H Kulhawy eds.). Proceeding of the congress, Eyanston, Illinois, June 25-29, 1989. Fellenius B H (2001). From strain measurements to load in an instrumented pile. Geotechnical News Magazine, Vol. 19, No. 1, pp. 35-38. Feng S H, Leung C F, Chow Y K and Dasari G R (2002). Centrifuge modeling of pile responses due to tunnelling. 15th KKCNN Symposium on Civil Engineering, Singapore, 19-20 December 2002, pp. G31-36. Forth R A and Thorley C B B (1996). Hong Kong Island Line – Predictions and performance. 2nd Intenational Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, Mair & Taylor (eds), pp. 677-682. Fujita K (1989). Special Lecture B: Underground construction, tunnel, underground transportation. 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 19892, pp.159-2176. Fukuoka M (1977). The effects of horizontal loads on piles due to landslides. 9th International Conference on Soil Mechanics and Foundation Engineering, Tokyo, Japan, pp.77-80. Georgiannou V N, Rampello S and Silvestri F (1991). Static and dynamic measurement of undrained stiffness of natural overconsolidated clays. Proceeding of the 10th European Conference on Soil Mechanics, Florence, Vol. 1, pp.91-96. Goh A T C, Wong K S, Teh C I and Wen D (2003). Pile response adjacent to braced excavation. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, April 2003, pp.383-386.

325

Guedes P F M de Melo and Pereira C S (2000). The role of the soil Ko value in numerical analysis of shallow tunnels. Geotechnical Aspects of Underground Construction in Soft Ground. Kusakabe, Fujita & Miyazaki (eds), pp.379-384. Gunn M J (1993). The prediction of surface settlement profiles due to tunnelling. Predictive soil mechanics. Thomas Telford, London, pp.305-316. Hergarden H J A M, Poel J T and Schrier J S (1996). Ground movements due to tunnelling: Influence on pile foundations. 2nd Intenational Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, Mair & Taylor (eds), pp. 519-524. Hermann L R and Al-Yassin Z (1978). Numerical analysis of reinforced soil systems. Proc. ASCE Earth Reinforcement Symposium, Pittsburg, Pennsylvania, pp.428-457. Hibbitt, Karlsson and Sorenson Inc. (2001). ABAQUS User’s manual, Version 6.31. Hull T S (1987). The behaviour of laterally loaded piles. PhD thesis. University of Sydney, Sydney, Australia. Ikeda S, Saito T, Huang Y and Mori A (1996). Settlement of storehouses during the passage of two parallel shields through soft ground. 2nd International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground. Mair & Taylor (eds), pp. 367-372. Inose J, Irie H and Saitoh S (1992). Construction of large cross-section shield tunnel directly below extremely large building in Tokyo. Towards New Worlds in Tunnelling, Vieitez-Utesa & Montanez-Cartaxo (eds), pp.549-556. Jacobsz S W, Standing J R, Mair R J and Hagiwara T (2002). Centrifuge modelling of tunnelling near driven piles. 4th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, Toulouse, France, pp.89-94. Jacobsz S W, Bowers K H, Moss N A and Zanardo G (2005). The effects of tunneling on piled structures on the CTRL. 5th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, 15-17 June 2005, Amsterdam, The Netherlands. Jardine R J (1991). The cyclic behaviour of offshore piles. Chapter in ‘The cyclic Loading of Soils’, Brown and O’Reilly eds, Blackie & Son. Jardine R J, Potts D M, Fourie A B and Burland J B (1986). Studies of the influence of non-linear stress-strain characteristics in soil-structure interaction. Geotechnique 36, No. 3, pp.377-396. Jeong S, Kim S and Briaud J L (1997). Analysis of downdrag on pile groups by the finite element method. Computers and Geotechnics, Vol. 21, No. 2, pp.143-161. Kaalberg F J, Teunissen E A H, van Tol A F and Bosch J W (2005). Dutch research on the impact of shield tunnelling on pile foundations. 5th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, 15-17 June 2005, Amsterdam, The Netherlands. KarWinn, Rahardjo H and Seh C P (2001). Characterisation of residual soils in Singapore. Geotechnical Engineering, 23(1), pp. 1-14.

326

Kimura T and Mair R J (1981). Centrifugal testing of model tunnels in soft clay. 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm. Kitiyodom P, Matsumoto T and Kawaguchi K (2004). Analysis of piled raft foundation subjected to ground movement induced by tunnelling. 15th Southeast Asian Geotechnical Society Conference, 22-26 November 2004, Bangkok, Thailand, pp. 183-188. Knight-Hassell C K and Tan K B (2000). Tunnelling through challenging ground conditions in Singapore. Proceeding of the International Conference on Tunnels and Underground Structures, Singapore, 26-29 November 2000, pp.633-638. Komiya K, Soga K, Akagi H, Hagiwara T and Bolton M (1999). Finite element modeling of excavation and advancement processes of a shield tunnlling machine. Soils and Foundations, Vol. 39, No. 3, pp.37-52. Kovacevic N, Edmonds H E, Mair R J, Higgins K G and Potts D M (1996). Numerical modeling of the NATM and compensation grouting trial at Redcross Way. 2nd Intenational Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, Mair & Taylor (eds), pp.553-559. Krishnan R (2000). Tunnelling and underground projects in Singapore. Proceeding of the International Conference on Tunnels and Underground Structures, Singapore, 26-29 November 2000, pp.89-95. Kuwabara F and Poulos H G (1989). Downdrag forces in group of piles. ASCE Journal of Geotechnical Engineering, 115, No. 6, pp.806-818. Lee C H, Tan S A and Dasari G R (2002). 2-Dimensional and 3-dimensional comparisons of finite element analysis of a soil nail problem. The 15th KKCNN Symposium on Civil Engineering, 19-20 December 2002, Singapore. Lee C J, Bolton M D and Al-Tabbaa A (2002). Numerical modelling of group effects on the distribution of dragloads in pile foundations. Geotechnique 52, No. 5, pp.325-335. Lee C J and Chiang K H (2004). Load transfer on single pile near new tunneling in sandy ground. Engineering Practice and Performance of Soft Deposits, IS-OSAKA, pp. 501-506. Lee G T K and Ng C W W (2005). Effects of advancing open face tunneling on an existing loaded pile. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 131, No. 2, pp. 193-201. Lee K M and Rowe R K (1989). Deformation caused by surface loading and tunnelling : the role of elastic anisotropy. Geotechnique 39, No. 1, pp.125-140. Lee K M and Rowe R K (1991). An analysis of three-dimensional ground movements: the Thunder Bay tunnel. Canadian Geotechnical Journal, 28, pp.25-41. Lee K M, Rowe R K and Lo K Y (1992). Subsidence owing to tunneling 1: Estimating the gap parameter. Canadian Geotechnical Journal, 29, pp.929-940.

327

Lee R G, Turner A J and Whitworth L J (1994). Deformations caused by tunneling beneath a piled structure. XIII ICSMFE, New Delhi, India, pp. 873-878. Leong E C, Rahardjo H and Tang S K (2003). Characterisation and engineering properties of Singapore residual soils. Proceeding of the Characterisation and engineering properties of natural soils. Tan et al. (eds), Singapore, pp.1279-1304. Lim K C (2003). Three-dimensional finite element analysis of earth pressure balance tunnelling. PhD thesis, National University of Singapore. Lin D G, Tseng C T, Phienwej N and Suwansawat S (2002). 3-D deformation analysis of earth pressure balance shield tunneling in Bangkok subsoil. Journal of Southeast Asian Geotechnical Society, April 2002, pp.13-27. Loganathan N and Poulos H G (1998). Analytical prediction for tunneling-induced ground movements in clays. Journal of Geotechnical and Environmental Engineering, ASCE, 124(9), pp.846-856. Loganathan N (1999). Effect of tunnelling adjacent to pile foundations. PhD thesis. University of Sydney. Loganathan N, Poulos H G and Xu K J (2001). Ground and pile-group responses due to tunnelling, Soils and Foundations, Vol. 41, No. 1, pp.57-67. LTA (2000). Guide to carrying out restricted activities within railway protection and safety zones, Development & Building Control Department, Land Transport Authority, Singapore. Mair R J (1979). Discussion: Effects of tunnelling on the bearing capacity and settlement of piled foundations by Morton J D and King K H, Tunnelling ’79, pp. 65. Mair R J (1993). Unwin Memorial Lecture - Developments in geotechnical engineering research: application to tunnels and deep excavations. Proceedings of the Institution of Civil Engineers. Civil Engineering, 1993, 97 (1), pp.27-41. Mair R J, Taylor R N and Bracegirdle A (1993). Subsurface settlement profiles above tunnels in clays. Geotechnique, Vol. 43, No. 2, pp. 315-320. Mair R J, Taylor R N and Burland J B (1996). Prediction of ground movement and assessment of risk of building damage due to bored tunnelling. 2nd Intenational Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, Mair & Taylor (eds), pp. 713-718. Mair R J and Standing J R (2001). Discussion Session 3.3: Underground work in urban areas including its impact on existing infrastructure. Proceedings of the 15th International Conference on Soil Mechanics and Geotechnical Engineering, Volume 2, 27-31 August 2001, Istanbul, Turkey, pp.2715-2717. Maranha J R and Neves E M (2000). 3D analysis of ground displacements due to the construction of Lisbon underground. Proceedings of the International Conference on Geotechnical & Geological Engineering (GeoEng 200), Melbourne.

328

Matsumoto T, Kitiyodom P and Kawaguchi K (2005). Three-dimensional analyses of piled raft foundations subjected to ground movements induced by tunnelling. 5th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, 15-17 June 2005, Amsterdam, The Netherlands. Melis M, Medina L and Rodriguez J (2002). Prediction and analysis of subsidence induced by shield tunneling in the Madrid Metro extension. Canadian Geotechnical Journal, 39, pp.1273-1287. Mhroueh H and Shahrour I (2002). Three-dimensional finite element analysis of the interaction between tunneling and pile foundations, International Journal for Numerical and Analytical Methods in Geomechanics, Vol.26, pp.217-230. Moroto N, Ohno M and Fujimoto A (1995). Observational control of shield tunneling adjacent to bridge piers. 3rd Geotechnical Aspects of Underground Construction in Soft Ground, Tokyo, Japan, Fujita & Kusakabe (eds), pp. 241-244. Morton J D and King K H (1979). Effects of tunneling on the bearing capacity and settlement of piled foundations, Tunnelling ’79, pp. 57-64. Nakajima M, Saitoh S and Nakamura H (1992). Planning of underground railway directly below extremely large overhead expressway piers in Tokyo. Towards New Worlds in Tunnelling, Vieitez-Utesa & Montanez-Cartaxo (eds), pp. 81-88. Naylor D J (1982). A study of reinforced earth walls allowing strip slip. Proc. ASCE Earth Reinforcement Symposium, Pittsburg, Pennsylvania, pp.618-643 Ng C W W, Sun Y F and Lee K M (1998). Laboratory measurements of small strain stiffness of granitic saprolites. Geotechnical Engineering Journal, SEAGS, Vol. 29, No. 2. Ng C W W, Pun W K and Pang R P L (2000). Small strain stiffness of natural granitic saprolite in Hong Kong. Journal of Geotechnical and Geoenvironmental Engineering, Vol. 126, No. 9. Ng C W W and Wang Y (2001). Field and laboratory measurements of small strain stiffness of decomposed granites. Soils and Foundations, Vol. 41, No. 3, pp.57-71. Ong J C W, Chen D C and Nadarajah P (1999). A summary of preliminary pile load test results for North East Line. Proceeding of International Conference on Rail Transit, Singapore, pp.689-702. Osborne N, Noren C, Li G J, Chinniah R and Jonsson P (2004). Design and construction of MRT project Contract 825 of CCL1 in Singapore. 30th ITA-AITES World Tunnel Congress, 22-27 May 2004, Singapore. Ottaviani M (1975). Three-dimensional finite element analysis of vertically loaded pile groups. Geotechnique 25, No. 2, pp.159-174. Ou C Y, Hwang R N and Lai W J (1998). Surface settlement during shield tunneling at CH218 in Taipei. Canadian Geotechnical Journal. 35. pp.159-168. Panet M and Guenot A (1982). Analysis of convergence behind the face of a tunnel. Proc. Tunnelling ’82, London, The Institution of Mining & Metallurgy, pp.197-204.

329

Peck R B (1969). Deep excavations and tunneling in soft ground. Proceeding of 14th International Conference on Soil Mechanics and Foundation Engineering, Vol. 3, Hamburg, pp.1469-1472. Phienwej N (1997). Ground movements in shield tunnelling in Bangkok soils. 14th International Conference on Soil Mechanics and Foundation Engineering, Hamburg, Germany. Plaxis B V (2004). Validation and verification manual for Plaxis 3D Tunnel, Version 2 (Brinkgreve and Broere eds.) Poh K B, Chua N L and Tan S B (1985). Residual granite soil of Singapore. Proceedings of 8th Southeast Asian Geotechnical Conference, Kuala Lumpur, pp. 3.1-3.9. Potts D M and Zdravkovic L (2001). Finite element analysis in geotechnical engineering: Application, Thomas Telford, London. Poulos H G (1989). Pile behaviour-theory and application. 29th Rankine Lecture. Geotechnique, 39(3), 365-415. Poulos H G and Chen L T (1997). Pile response due to excavation-induced lateral soil movement. Journal of Geotechnical and Geoenvironmental Engineering, February 1997, pp. 94-99. Powderham A, Cording E and Geilen T (1999). JLE – London Bridge Station: Evaluation and control of excavation induced settlement on masonry and framed buildings. P1015 CIRIA. Powrie W and Li E S F (1991). Finite element analyses of an in situ wall propped at formation level. Geotechnique 41, No. 4, pp.499-514. Ran X, Leung C F and Chow Y K (2003). Centrifuge modeling of tunnel-pile interaction in clay. Underground Singapore 2003, pp. 256-263. Randolph M F (1981). Pilot study of lateral loading of piles due to soil movement caused by embankment loading, Report for the Department of Transport, Engineering Department, Cambridge University Richards D J and Powrie W (1994). Finite element analysis of construction sequences for propped retaining walls. Proceedings of the Institution of Civil Engineers, Geotechnical Engineering, 107, pp.207-216. Rowe R K, Lo K Y and Kack G J (1983). A method of estimating surface settlement above tunnel constructed in soft ground. Canadian Geotechnical Journal, Vol. 20, pp.11-22 Sawatparnich A and Kulhawy F H (2004). Simplified model to predict pile response caused by tunnelling in soils. 15th Southeast Asian Geotechnical Society Conference, 22-26 November 2004, Bangkok, Thailand, pp. 697-702. Schofield A N (1980). Cambridge geotechnical centrifuge operations. 20th Rankine Lecture. Geotechnique 20, No. 2, pp.129-170. Selemetas D, Standing J R, Mair R J, Sharrocks D M, Parker F and Allen R (2002). The response of a piled structure to tunnelling and jacking. 4th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, Toulouse, France.

330

Selemetas D, Standing J R and Mair R J (2005). The response of full-scale piles to tunnelling. 5th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, 15-17 June 2005, Amsterdam, The Netherlands. Shirlaw J N (2000). Discussion: Can settlement be accurately predicted using advanced numerical method. Geotechnical Aspect of Underground Construction in Soft Ground. Fujita & Miyazaki (eds). Shirlaw J N, Ong J C W, Rosser H B, Tan C G, Osborne N H and Heslop P E (2003). Local settlements and sinkholes due to EPB tunneling. Proceedings of the Institution of Civil Engineers: Geotechnical Engineering. Issue GE4, pp.193-211. Shirlaw J N, Richards D P, Ramond P and Longchamp P (2004). Recent experience in automatic tail void grouting with soft ground tunnel boring machines. ITA-AITES World Tunnel Congress, 22-27 May 2004, Singapore. Sousas L M R, Arslan U, Katzenbach R, Festag G and Dolz K (2001). Numerical analysis of a shield driven tunnel in Lisbon. Modern Tunneling Science and Technology, Adachi et al. (eds.), pp.625-628. Stewart D P (1992). Lateral loading of piled bridge abutments due to embankment construction. PhD thesis, University of Western Australia. Stewart D P, Jewell R J and Randolph M F (1993). Numerical modelling of piled bridge abutments on soft ground. Computer and Geotechnics 15, pp.21-46. Sujardinata J, Carter J P, Hull T S and Poulos H G (2005). Analysis of effects of tunnelling on single piles. 5th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, 15-17 June 2005, Amsterdam, The Netherlands. Swoboda G (1979). Finite element analysis of the New Austrian Tunnelling Method (NATM), Proc. 3rd International Conference on Numerical Method in Geomechanics, Aachen, Vol. 2, pp.581-586. Swoboda G and Abu-Krisha A (1999). Three-dimensional numerical modeling for TBM tunneling in consolidated clay. Journal of Tunnelling and Underground Space Technology, Vol. 14, No. 3, pp.327-333. Takahashi K, Fukazawa N, Hagiwara T and Hosoda M (2004). Observational control of slurry shield tunnels with super close spacing under the nearby bridge abutments loads. 30th AITES-ITA World Tunnel Congress, Singapore. Tan S B, Tan S L, Lim T L and Yang K S (1988). Landslide problems and their control in Singapore. Proceedings of 9th Southeast Asian Geotechnical Conference, Bangkok, Thailand, Vol. 1, pp. 25-36. Taylor R N and Grant R J (1998). Centrifuge modelling of the influence of surface structures on tunnelling induced ground movements. Tunnels and Metropolises, Negro Jr & Ferreira (eds), pp.261-266.

331

Teh C I and Wong K S (1995). Analysis of downdrag on pile groups. Geotechnique 45, No. 2, pp.191-207. Tham K S and Deutscher M S (2000). Tunnelling under Woodleigh Workers’ Quarters on Contract C705. Tunnels and Underground Structures, Zhao, Shirlaw & Krishnan (eds), pp. 241-249. Tomlinson M J (1977). Pile design and construction practice. Viewpoint publication. Vermeer P A and Bonnier P G (1991). Pile settlements due to tunneling. 10th European Conference on Soil Mechanics and Foundation Engineering, Florence, Italy, pp.869-872. Viggiani G and Atkinson J H (1995). Stiffness of fine-grained soil at very small strains. Geotechnique 45, No.2, PP.249-265. Wakai A, Gose S and Ugai K (1999). 3-D elasto-plastic finite element analyses of pile foundations subjected to lateral loading. Soils and Foundations, Vol. 39, No. 1, pp.97-111. Wang X N (2003). Field monitoring and back-analysis of soldiers piles retaining wall for deep excavation. PhD thesis, National University of Singapore. Wood D M (1990). Soil behaviour and critical state soil mechanics. Cambridge University Press. Yang K S and Tang S K (1997). Stabilising the slope of Bukit Gombak. Proceedings of 3YGEC, Singapore, pp. 589-605. Yang Z H and Jeremic B (2003). Numerical study of group effects for pile groups in sands. International Journal for Numerical and Analytical Methods in Geomechanics, 27, pp.1255-1276. Yong K Y, Lee F H, Tan T S and Lee S L (1998). Excavation near critical structures bridging research and practice. Proceedings of the 13th Southeast Asian Geotechnical Conference, 16-20 November 1998, Taipei, Taiwan, pp. 69-80. Yong K Y and Pang C H (2004a). Geotechnical challenges of the mass rapid transit (MRT) system in Singapore. Special lecture, Malaysian Geotechnical Conference, 15-17 March 2004, Petaling Jaya, Malaysia, pp.119-130. Yong K Y and Pang C H (2004b). Effects of construction of underground Mass Rapid Transit on nearby piled-structures, Special Lecture, 15th Southeast Asian Geotechnical Conference, 22-26 November 2004, Bangkok, Thailand. Zhou Y (2001). Engineering geology and rock mass properties of the Bukit Timah Granite. Proceedings of Underground Singapore 2001, Singapore, pp.308-314. Zhu H (1999). Evaluation of load transfer behavior of bored piles in residual soil incorporating construction effect. PhD thesis, Nanyang Technological University. Zhu H and Chang M F (2002). Load transfer curves along bored piles considering modulus degradation. Journal of Geotechnical and Geoenvironmental engineering, September issue, pp. 764-774.

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APPENDIX A PILE STIFFNESS FOR MRT NEL C704

First, the tangent modulus method proposed by Fellenius (1989) was used to derive the variation

of modulus with strain based on a pile load test carried out. The pile tested had a similar concrete

mix, reinforcement and installation procedure as other piles at the viaducts. The pile was

instrumented with thirty-two vibrating wire strain gauges and three telltale extensometers.

According to Fellenius (1989), the tangent modulus is represented as follow:-

BAE tt += ε [A.1]

Where as the secant modulus to be used for converting strain to stress is as follow:-

BAE ts += ε5.0 [A.2]

where At is the slope of tangent modulus line (GPa/µε), B is the intercept of the tangent modulus

i.e. initial tangent modulus (GPa). Figure A.1 shows a plot of the tangent modulus against the

strain based on all the strain gauges and tell-tales in the pile. By curve fitting, At is derived as -

0.02 GPa/µε and B is within 30 to 50 GPa. There seems to be a large variation between the upper

and lower bounds. This is likely to be due to the amount of shaft resistance mobilised at different

depth. The larger the shaft resistance, the lower the tangent modulus line (Fellenius, 2001).

Another possibility could be due to the bored pile installation method. The concrete was poured by

tremie pipe and did not go through vibrating compaction, which leads to non-uniform property at

different depth.

Besides, the constant Young’s modulus for concrete (Ec) can be interpreted based on an

approximate method by ACI (1989) as follows:

333

'cc f151000E = kPa [A.3]

where is the characteristic compressive cylinder strength of concrete at 28 days (in kPa). The

piles were constructed using Grade 45 concrete. The can be approximated as 0.8 times

from cube strength. Ultimately, the modulus was derived as 28.65GPa.

'cf

'cf cuf

Figure A.2b compares the axial force interpreted for one of the piles during tunnelling. Firstly, a

variation of approximately 40% was noted for the upper and lower bounds using the tangent

modulus method. Secondly, the lower bound value was similar to the value using ACI method.

Despite the variation, the results to be presented in Chapter 3 were interpreted based on the ACI

method.

0

50

100

150

200

250

300

0 50 100 150 200 250 300 350 400

Microstrain (µ ε)

Tang

ent m

odul

us, E

t (G

Pa)

TT-1 (1st cycle)TT-2 (1st cycle)A (1st cycle)B (1st cycle)D (1st cycle)E (1st cycle)F (1st cycle)G (1st cycle)H (1st cycle)I (1st cycle)J (1st cycle)K (1st cycle)L (1st cycle)M (1st cycle)N (1st cycle)O (1st cycle)Curve fit (Upper bound)Curve fit (Lower bound)

Strain gauge and telltale data at 1st cycle

48m

ABCD

EFGHIJKL

MN

O

TT2

TT1

Figure A.1 Tangent modulus derived from a pile load test

334

0

5

10

15

20

25

30

35

-200-150-100-500

Microstrain (µε)

Dep

th (m

.b.g

.l.)

X1 Y1X2 Y2Average

X

Y1

Y2

X2

Plan view of strain gauges arrangement in each level

0

5

10

15

20

25

30

35

-8000-7000-6000-5000-4000-3000-2000-10000

Axial force (kN)

Dep

th (m

.b.g

.l.)

Constant E (ACI, 1989)

Strain dependent E (Upper)

Strain dependent E (Lower)

SB

Tunnel springline

NB Tunnel

SB Tunnel

Tunnel springline

(a) (b)

Figure A.2 Influence of (a) non-uniform strain distribution and (b) pile stiffness in the interpretation of axial force in pile

335

APPENDIX B PILE MOMENT OF INERTIA FOR MRT NEL C704

Besides the Young’s modulus, moment of inertia (Ipile) is another variable that could affect the

interpretation of bending moment. Depending on the significance of bending moment, the pile

section could be in an un-cracked state (Ipile=Igross), fully cracked (Ipile=Icracked) or in between. In

order to investigate the appropriateness of the moment of inertia adopted, all the bending moments

reported in Chapter 3 were first interpreted using Igross. The bending moments were then compared

to the cracked moment (Mcr) which can be computed from the following:-

zIf

M grossrcr = [B.1]

where fr is the modulus of rupture of concrete and is equal to '7. cf19 (in kPa) as recommended

by ACI (1989), z is the distance from the centroid to the extreme fibre of the pile in tension (m)

and Igross is the gross moment of inertia (m4) which is calculated as 64

. 4pileDπ

.

The Mcr was calculated to be 634kNm and 2140kN for 1.2m and 1.8m diameter piles respectively.

Figure B.1 shows the bending moment computed for all the 1.2m diameter instrumented piles

(using Igross) and the cracked moment envelope. Generally, the bending moment at all four levels

of the piles stayed within the cracked moment envelope after the two tunnels were driven.

However, there were some points within the piles where bending moment exceeded the cracked

moment (particularly at Pier 11). It is observed that the bending moments exceeding the cracked

moment were developed during the construction of the viaduct bridge (which exerted further

loading on the piles).

336

Despite some points exceeding the cracked state, bending moment to be presented subsequently is

based on Igross. It is realised that Igross as assumed for the computation of bending moment

exceeding cracked moment would over-estimate the actual bending moment. Further assessment

of the effective moment of inertia is not within the scope of this research.

-1500

-1000

-500

0

500

1000

1500

-1500 -1000 -500 0 500 1000 1500

Transverse bending moment, Mxx (kNm)

Long

itudi

nal b

endi

ng m

omen

t, M

yy

(kN

m)

Cracking moment

Cracking m

oment

M > Mcr

M < Mcr

Figure B.1 Computed bending moments and cracked moment envelope

337

APPENDIX C

C.1 Comparison of pile responses between SDMCC and NLES models

0

10

20

30

40

50

60

70

-5000-4000-3000-2000-10000Axial force (kN)

Dep

th (m

)

Pile P1 (SDMCC)Pile P1 (NLES)Measured (Pile P1)

1.6m

P2P1

P4 P3

0

10

20

30

40

50

60

70

-5-4-3-2-10Pile settlement (mm)

Dep

th (m

)

Pile P1 (SDMCC)Pile P1 (NLES)

1.6m

P2P1

P4 P3

0

10

20

30

40

50

60

70

-20-15-10-50Pile lateral deflection - transverse (mm)

Dep

th (m

)

Pile P1 (SDMCC)Pile P1 (NLES)

SB

1.6m

P2P1

P4 P3

Tunnel springline

SB

Tun

nel

Tunnel springline

SB

Tun

nel

Tunnel springline

SB

Tun

nel

(a) (b) (c)

Figure C.1 Comparison of pile responses with respect to SDMCC and NLES models (a) Pile axial force (b) Pile settlement (c) Pile lateral deflection

338

C.2 Comparison of pile responses between 3-D tunnel advancement and plane strain tunnel procedures

0

10

20

30

40

50

60

70

-20000-15000-10000-50000Axial force (kN)

Dep

th (m

)

3-D tunnel adv. (WL+tunnelling)Plane strain tunnel (WL+tunnelling)3-D tunnel adv. (WL)Plane strain tunnel (WL)

With WL, Gmax/p'=800, VL=1%, Lp/Htun=3.0, Xpile/Dtun=1.0

Tunnel

0

10

20

30

40

50

60

70

-15-10-50Pile settlement (mm)

Dep

th (m

)

3-D tunnel adv. (WL+tunnelling)Plane strain tunnel (WL+tunnelling)

With WL, Gmax/p'=800, VL= 1%, Lp/Htun=3.0, Xpile/Dtun=1.0

Tunnel

0

10

20

30

40

50

60

70

-15-10-50

Pile lateral deflection - transverse (mm)

Dep

th (m

)

3-D tunnel adv. (WL+tunnelling)Plane strain tunnel (WL+tunnelling)

Tunnel

With WL, Gmax/p'=800, VL=1%, Lp/Htun=3.0, Xpile/Dtun=1.0

Tunnel springline Tunnel springline

(a) (b) (c)

Figure C.2 Comparison of pile responses with respect to different numerical simulation procedures (a) Pile axial force (b) Pile settlement (c) Pile lateral deflection

339

APPENDIX D OTHER INFLUENCING FACTORS IN PLANE STRAIN FE ANALYSIS

The calibration charts as presented in Chapter 6 only hold for the assumed cases particularly the

adopted soil model (non-linear elastic), earth pressure at-rest, Ko (=1.0) and single tunnel

simulation. These assumptions are further investigated here.

D.1 Effect of soil model

To-date, there are probably hundreds of constitutive models available which allows the

characteristics of soil to be modelled. Therefore, it is impossible to investigate every one of the

models. At here, the commonly used ‘Mohr-Coulomb’ model is compared to the ‘Non-linear

elastic’ model. The tunnel-pile configuration and dimension remained the same in both analyses.

Total stress analysis was carried out with the Young’s modulus of soil, Eu of 30,000kPa, undrained

shear strength, Cu of 150kPa and angle of shearing resistance, φ’ of 0o. Figure D.1 shows the

convergence plots for both the pile horizontal deflection and pile head settlement. It can be

observed that the modification factors differ up to two times for the two different models. Strictly

speaking, it is hard to justify the variation of modification factors for different soil models since

the input parameters also play a role in determining the factors. It is not within the scope of this

study to quantify the effect of soil model.

D.2 Effect of soil earth pressure at-rest

All the analyses that have been presented so far assumed the soil earth pressure at-rest, Ko of 1.0.

However, Ko is commonly found to be less than 1.0 in soft normally consolidated soil and more

than 1.0 in stiff over-consolidated soil. Figure D.2 shows a comparison of convergence and the

340

corresponding modification factor between Ko of 1.0 and 1.5 in non-linear elastic model. As can

be observed, the Ko parameter plays a small part in varying the modification factors in both the

pile horizontal deflection and pile head settlement. However, it should be noted that the influence

of Ko parameter is highly dependent on the type of soil model adopted.

Figure D.1 Influence of soil model on pile stiffness modification factor

0

50

100

150

200

250

0.0 0.1 0.2 0.3 0.4 0

Figure D.2 Influence of soil earth pressure at-rest on pile stiffness modification factor

.5Pile stiffness ratio, Ewall(2D) / Epile(3D)

Resp

onse

of 2

D to

3D

anal

ysis

(%)

Pile max. horiz. defl. (NE, Ko=1.0)Pile max. horiz. defl. (NE, Ko=1.5)Pile head sett. (NE, Ko=1.0)Pile head sett. (NE, Ko=1.5)

0.07

0.12

2D response = 3D single pile response

2D response = 3D single pile response

0

50

100

150

200

250

300

350

0.0 0.1 0.2 0.3 0.4 0.5Pile stiffness ratio, Ewall(2D) / Epile(3D)

Resp

onse

of 2

D to

3D

anal

ysis

(%)

Pile max. horiz. defl. (Non linear)Pile max. horiz. defl. (Mohr Coulomb)Pile head sett (Non linear)Pile head sett. (Mohr Coulomb)

0.07

0.15

341

D.3 Effect of twin tunnel simulation

The modification factor as investigated in Chapter 6 assumed a single tunnel simulation. However,

in practice, there is a likelihood of encountering multiple tunnels interaction. Study was also

carried out to investigate the sensitivity of twin tunnels on the modification factor. Two cases were

simulated; single pile and one-row pile group. Figures E.3a and b show respectively the typical 3-

D and 2-D mesh adopted for simulation of the twin tunnels which are located on each side of the

single pile. Equal distance between tunnel and pile was modelled on each side of the pile (i.e.

Xpile=5.45m). Other tunnel-pile configuration and dimension remained the same as the typical case

described in Section 6.4.2. Figures D.4a and b compare the convergence obtained for pile

horizontal deflection and pile head settlement respectively. From the negligible differences, it can

be concluded that the modification factor is not affected by the twin tunnels in both single pile and

one-row pile group.

342

74m

(a)

72m

72m

30m

(b) m

74m

Figure D.3 Typical mesh for twin tunnels simulation withD mesh

72m

72

single pile (a) 3-D mesh (b) 2-

343

(a)

(b)

Figure D.4 Influence of twin tunnels advancement on pile stiffness modification factor (a) Pile maximum horizontal deflection (b) Pile head settlement

0

50

100

150

200

250

300

350

0.0 0.1 0.2 0.3 0.4 0.5Pile stiffness ratio, Ewall(2D) / Epile(3D)

Resp

onse

of 2

D to

3D

anal

ysis

(%)

Single pile (Single tunnel)Single pile (Twin tunnel)1-row pile group (Single tunnel)1-row pile group (Twin tunnel)

D pile = 1.2m, E pile = 28GPaG max /P' = 800, V L = 1.81%Tunnel-pile dist. = 5.45mPile head settlement

0.25

0.12

2D response = 3D single pile response

2D response = 3D single pile response

0

50

100

150

200

250

300

350

0.0 0.1 0.2 0.3 0.4 0.5

Pile stiffness ratio, Ewall(2D) / Epile(3D)

Resp

onse

of 2

D to

3D

anal

ysis

(%)

Single pile (Single tunnel)Single pile (Twin tunnel)1-row pile (Single tunnel)1-row pile (Twin tunnel)

D pile = 1.2m, E pile = 28GPaG max /P' = 800, V L = 1.81%Tunnel-pile dist. = 5.45mPile lateral deflection

0.08

0.16

344

APPENDIX E MRT CIRCLE LINE STAGE 1 CONTRACT C825 SINGAPORE

E.1 Background and overview

The on-going Contract C825 project formed the first stage of the Circle Line construction (CCL1).

The CCL1 line, also known as the Marina Line is part of the five stages to be built (Yong & Pang,

2004b). In the contract, four stations namely the Dhoby Ghaut Station, Museum Station,

Convention Centre Station and Millenia Station are to be built. The contract also includes the

construction of twin tunnels of 1.5km long. All the constructions are located in the densely

populated civic and business district centre of Singapore. Inevitably, the construction has to be

carried out very near to existing heritage structures such as Raffles Hotel, Singapore Arts

Museum, Cathedral and various high-rise buildings. Figure E.1 shows the location of tunnels,

stations and also the close proximity structures in Contract 825. Further details on the project can

be found in Osborne et al. (2004).

Stamford Canal

Overrun Tunnel

Bored tunnel

Cathedral of the Good Shepherd

Singapore Art Museum

Bored tunnel

Existing MRT East-West Line

Raffles Hotel

Future Art Centre Line C & C

Tunnel

Temporary TBM Launching Shaft

Stamford Canal

C & C Tunnel

MRT CCL1 Contract 825

Pan Pacific Hotel

Marina Square

Underground Carpark Link

Bored tunnel

JRLBTL ERLEWL

NEL

CCL

LRTLRT

C825

Stamford Canal

Overrun Tunnel

Bored tunnel

Cathedral of the Good Shepherd

Singapore Art Museum

Bored tunnel

Existing MRT East-West Line

Raffles Hotel

Future Art Centre Line C & C

Tunnel

Temporary TBM Launching Shaft

Stamford Canal

C & C Tunnel

MRT CCL1 Contract 825

Pan Pacific Hotel

Marina Square

Underground Carpark Link

Bored tunnel

JRLBTL ERLEWL

NEL

CCL

LRTLRT

C825

JRLBTL ERLEWL

NEL

CCL

LRTLRT

C825

Dhoby Ghaut Station

Museum Station

Convention Centre Station

Millenia Station

NSL

Dhoby Ghaut Station

Museum Station

Convention Centre Station

Millenia Station

NSLNSL

Figure E.1 Location of MRT Circle Line C825

345

In this project, one of the great challenges posed to engineers was to construct tunnels under an

existing building beneath the Raffles Boulevard. Figure E.2 shows the twin tunnels bored under

the 5-storey frame concrete structure which includes a basement carpark. The two tunnels

configured in a vertically stack alignment passed beneath the structure which link the Marina

Square and the Pan Pacific Hotel. The structure is supported on driven Raymond Step-Taper steel

piles of 324mm diameter. The piles are founded at a depth of approximately 11.5m below the

basement. The main columns are supported on pile groups of four, eleven and seventeen piles

whereas the wall sits on a stretch of single piles. The piles are located as close as 1.12m to the

tunnel extrados. Two EPB shield machines of 6.58m diameter were used to bore the twin tunnels

and were located very near to each other with a clear spacing of 3.84m from their extrados. The

upper tunnel is located at a depth of 12.5m below the basement car park.

Figure E.2 Tunnelling under the link structure between Pan Pacific Hotel and Marina Square

346

E.2 Geology and ground conditions

From the soil investigation carried out, the structure is generally founded on the Old Alluvium

with the degree of weathering varying with depth. The Old Alluvium is an alluvial deposit that has

been variably cemented and has the strength of weak rock (LTA, 2001). The Old Alluvium which

composed of silty sandy clay can be classified into five classes, i.e. OA1 to OA5 which are

defined by the SPT-N of <10, 10 to 30, 30 to 50, 50 to 100 and >100 respectively. However, the

7m of soil below the basement consists of mixed layers of fluvial sand (F1) and clay (F2), marine

clay (M) and fill material, typically the Kallang Formation (Fig. E.2). Ground water is close to the

original ground level. The piles are generally founded on the dense Old Alluvium material (i.e.

OA5). Material of OA3 to OA5 was encountered during the north bound tunnel advancement

whereas the south bound tunnel encountered only OA5 material.

E.3 Construction sequence

The tunnels were driven by two earth pressure balance machine (EPBM) manufactured by

Herrenknecht and has an outer diameter of 6.58m and length of 8m. When the EPBM were under

the building, good soil condition was encountered, therefore leading to good advance rate (i.e.

approximately 50mm/min) and progress rate (up to 10 rings/day). A face pressure of 150kPa was

maintained in the chamber to provide face stability although it is realised that the material

encountered is generally stable and has a considerable stand-up time even without the pressure.

The first EPBM (for North bound tunnel) was launched from Millenia Station on the 22 January

2003 and advance towards the Convention Centre Station. This is followed by the second EPBM

(for South bound tunnel) which was launched two months later from the same launching shaft.

The construction of the tunnels were scheduled such that the lower tunnel was bored first and

followed by the upper tunnel to minimise the effect on the structure. Initially the tunnels started

347

off in a horizontally parallel position for length of approximately 230m (Figure E.3a). However,

the tunnels were then gradually shifted into a vertically stacked alignment when reaching the link

structure due to space constraint from the pile foundation (Figure E.3b).

SBtunnel

NBtunnel

Pan Pacific Hotel **

Marina Square **

Raffles Boulevard

(a)

Link structure

NBtunnel

SBtunnel

SBtunnel

NBtunnel

Pan Pacific Hotel **

Marina Square **

*Not to scale** Foundation not illustrated

Road

Pedestrian Link

Car park Link

(b)

Figure E.3 Alignment of tunnels (a) before reaching structure (b) under structure

348

8500 850010600

8500 850010600

8600

8600

8600

8600

8600

CL OF TUNNEL

LEGEND

EXISTING PILEEXISTING PILE TO BE CUT-OFF

PG1

PG2

PG4

PG3

PG6

PG5

PG8

PG7

PG10

PG9

PG11

PG12

PG13

PG14

PG15

PG17

PG16

PG18

PG19

PG20

P1 P5P4bP3P2 P7P6

P8 P11P10P9 P13P12 P14

P4a

8500 850010600

8500 850010600

8600

8600

8600

8600

8600

CL OF TUNNEL

LEGEND

EXISTING PILEEXISTING PILE TO BE CUT-OFF

PG1

PG2

PG4

PG3

PG6

PG5

PG8

PG7

PG10

PG9

PG11

PG12

PG13

PG14

PG15

PG17

PG16

PG18

PG19

PG20

P1 P5P4bP3P2 P7P6

P8 P11P10P9 P13P12 P14

P4a

PAN

PA

CIF

IC H

OTE

L

MA

RIN

A S

QU

AR

E

TOWARDS CONVENTION CENTRE STATION

TOWARDS MILLENIA STATION

Tunn

ellin

gdi

rect

ion

PAN

PA

CIF

IC H

OTE

L

MA

RIN

A S

QU

AR

E

TOWARDS CONVENTION CENTRE STATION

TOWARDS MILLENIA STATION

Tunn

ellin

gdi

rect

ion

Figure E.4 Foundation layout of the link structure

349

Figure E.4 shows the foundation layout of the building and the tunnel location. One of the main

challenges in this section was the intersection of three numbers of piles with the upper tunnel

(Figure E.5). Two piles were encountered at the front wall and one pile at the rear wall of the

structure. Initially, only two piles were expected. However, an unexpected H-pile of 375mm x

375mm was encountered exactly adjacent to one of the piles to be expected during tunnelling.

Approximately 3m length of each pile was to be removed to allow the tunnel machine to pass

through. The EPBM was stopped allowing the piles to be cut-off manually. To avoid loading on

the tunnel lining, polystyrene foam block was attached to the base of the pile (Figure E.6). Figure

E.7 shows the view inside the chamber during pile removal and Figure E.8 shows the scrap piles

after removal.

6

5

4

3

7

IT SHALL BE THE RESPONSIBILITY OF THE CONTRACTOR TO FURNISH STEEL SHELLS OF SUFFICIENT STRENGTH AND THICKNESS TO ENABLE THEM TO BE DRIVEN TO THE REQUIRED PENETRATION OR RESISTANCE WITHOUT DAMAGE DUE TO IN-PLACE SOIL PRESSURES. THE SHELL FOR THE LOWER 1/3 OF THE PILE SHALL BE AT LEAST 14 CAGE

CONCRETE FILL SHALL BE NORMAL WEIGHT AND HAVE A MINIMUM 28 DAY COMPRESSIVE CUBE STRENGTH OF 4.3 N/mm (6250 PSI)

19mm (3/4") THICKCLOSURE PLATESECURELY WELDED

O PIPET

(TYP

ICA

L)75

0

441mm

416mm

391mm

340mm

365mm

3658

(12'

0") S

ECTI

ON

S A

S R

EQU

IRED

LEN

GTH

AS

RE

QUI

RE

D

BASEMENT LEVEL 98.916

ROAD LEVEL 103.15

EXISTING PILEEXISTING PILE TO CUT TO 300mm ABOVE PROPOSED TUNNEL LINING

TUNNEL

Figure E.5 Detailed of Raymond step-tapered pile

350

CL

3m

CL

0.4m

UPPER TUNNEL (NB) UPPER TUNNEL (NB)

PIPE PILE

STEEL H-PILE

STEEL H-PILE

PIPE PILE

POLYFOAMBLOCK

(a) (b)

Figure E.6 Pile cut-off at one of the wall section (a) before (b) after

Raymond Step-taper pile

Figure E.7 A view inside the chamber during pile removal

351

Raymond Step-Taper pile

(a)

Steel H-pile

(b)

Figure E.8 Scrap of removed piles (a) Raymond Step-Taper pile (b) Steel H-pile

352

E.4 Monitoring scheme and results

As part of the stringent requirement laid by the Land Transport Authority (LTA), the building was

fully instrumented. Settlement markers were installed in almost all the columns at the basement

level of the structure. In addition, tilt meters and tape extensometers were also installed in some of

the columns and walls.

During the advancement of the SB tunnel, the maximum column settlement recorded is only up to

3mm. Subsequently, after the NB tunnel has advanced, the maximum accumulated settlement is

up to 7mm. Figure E.9 plots all the columns settlements in three-dimensional visualisation for

cases when the face of the second EPBM (for NB tunnel) was (a) at the front wall of structure (b)

at the rear wall of structure (c) at a distance of 10 times tunnel diameter away from the rear wall.

With relatively good ground conditions and well controlled tunnelling procedure, the maximum

and differential measured settlements were kept small.

353

9 OCT 2003

20 OCT 2003

11 NOV 2003

POSITIONOF EPBM

MAX. 2mm

MARINA SQUARE

PAN PACIFIC HOTEL

(a)

MARINA SQUARE

PAN PACIFIC HOTEL

MAX. 4.4mm

(b)

POSITIONOF EPBM

MAX. 7mm

MARINA SQUARE

PAN PACIFIC HOTEL

(c)

Figure E.9 Measured building settlement for NB tunnel advancement (a) EPBM at front wall (b) EPBM at rear wall (c) EPBM leaving the structure

354

APPENDIX F PLANE STRAIN FE ANALYSIS OF CENTRIFUGE TESTS

Three centrifuge tests were carried out by Loganathan (1999) to study the response of pile

foundation due to tunnelling. All the magnitudes reported herein are based on the prototype value.

The only difference between each test was the tunnel depth i.e. 15m (Test 1), 18m (Test 2) and

21m (Test 3). The pile diameter and length was 0.8m and 18m respectively. A single pile and 2x2

pile group were arranged on each side of the tunnel. The distance between tunnel axis and the

centre of single pile was 5.5m. The same distance was also arranged between tunnel axis and

centre of the front pile of 2x2 pile group. Piles in the pile group were spaced at a distance of 2.5m

which is equivalent to three times pile diameter. Pre-tunnelling loading of 1340kN and 4550kN

were applied to the single pile and pile group respectively. A schematic diagram of the tests set-up

is shown in Figure F.1. All the tests were carried out in stiff Kaolin clay with undrained shear

strength typically varied from 25kPa at the surface to 100kPa at the 25m.b.g.l. Volume loss was

simulated by removing the silicone oil in the model uniformly and therefore represents a plane

strain tunnel.

Test 1 : Y1 = 15mTest 2 : Y1 = 18mTest 3 : Y1 = 21m

2.1m

Y1

30m

32.5m32.5m

2.5m

Pile cap thickness = 1mCap-soil gap = 0.1m

4m

Lp = 18m

Test 1

Test 2

Test 3

D = 6m

Dp = 0.8m

Ground surface

Figure F.1 Schematic diagram showing the position and dimension of tunnel and piles in

the centrifuge tests (prototype dimension)

355

FE analysis was carried out on two tests, i.e. Tests 1 and 3. Dimension of the mesh followed

exactly the dimension of centrifuge strongbox in prototype scale. Exploiting the plane of

symmetry at tunnel axis, dimension of mesh was reduced to 32.5m x 30m in horizontal and

vertical axis respectively. The type of element and node are similar as used in all the studies

described above. Besides, same soil model was also adopted. A normalised soil stiffness, Gmax/p’

of 500 was assigned. The analysis was carried out in three steps:-

• Step 1: Generating the initial stress in soil

• Step 2: Pile foundation is wished-in-place and loaded

• Step 3: Tunnel is allowed to deform under convergence confinement method to the

required volume loss of 1% (undrained)

Following are the required parameters to determine the modification factor from calibration

charts:-

• Pile foundation configuration = Single pile and 2x2 pile group

• Loading condition = With pre-tunnelling loading (1340kN for single pile and 4550kN for

pile group)

• Pile diameter, Dpile = 0.8m

• Pile length to tunnel depth ratio, Lp/Htun = 1.2 (Test 1) & 0.86 (Test 3)

• Pile-tunnel distance, Xpile = 5.5m (or Xpile/Dtun = 0.92)

• Pile stiffness, Epile = 200GPa

• Tunnel diameter, Dtun = 6m (single tunnel)

• Tunnel volume loss, VL = 1%

• Normalised soil shear stiffness, Gmax/p’ = 500

According to the above parameters, the tests fall into Condition 2 (single pile with pre-tunnelling

loading) and Condition 4 (pile group with pre-tunnelling loading). As described in Section 6.6.4,

356

the conditions coupled with Lp/Htun of 1.0 or less do not allow convergence between 2-D and 3-D

analyses. A set of Ewall(2D) was assumed as sensitivity studies.

Figures F.2a, b and c show the predicted and measured greenfield surface settlement, lateral soil

movement and soil settlement of Test 1 respectively. No pile was yet included in the analysis so

that the greenfield model can be first compared. Very good match was obtained for both

magnitude and trend despite the simple model adopted. Figures F.3a and b show the single pile

lateral deflection and pile head settlement of Test 1 respectively. Five analyses were carried out

with varying pile stiffness modification factor, i.e. 0.33, 0.46, 0.63, 1.0 and 1.5 which were

computed from the equivalent pile stiffness method. To be noted, the modification factor has no

influence on the pile response. This agrees with the calibration charts in Section 6.6.2 where no

convergence was observed for the similar condition. However, both the pile lateral deflection and

settlement were well predicted with the model.

In the analysis of pile group of Test 1, the lateral deflection of front pile and pile head settlement

are shown in Figures F.4a and b respectively. In this situation, the predicted profile of lateral

deflection was off track from the measured. The lateral deflection is higher at the pile head instead

of the pile tip. This is likely to be the restraint from pile length below tunnel springline and the

inability of soil flow above the tunnel which causes large displacement on the upper length of

piles. Besides, the 2-D analysis over-predicts pile head settlement by approximately two times

(Figure F.4b).

For Test 3, the predicted and measured greenfield soil movement are shown in Figure F.5. Again,

all the predicted trend and magnitude match very well with the measured. However, for the single

pile response, FE analysis could not resemble the trend of measured lateral deflection profile

357

(Figure F.6a). But the predicted maximum deflection is very close to the measured. Furthermore,

the pile head settlement is over-predicted by about 2.6 times (Figure F.6b).

The pile group prediction for Test 3 is also notably off sight from the measurement. Figures F.7a

and b show the lateral deflection of front pile and pile head settlement respectively. A more

flexible profile of deflection was observed in the FE analysis whereas the measurement shows the

pile to move in a rigid form by translation. Besides, the pile settlement is highly over-predicted by

four to five times (Figure F.7b). Even a high increment of pile stiffness (i.e. modification factor of

3.0) could not arrest the large settlement.

358

-20

-15

-10

-5

00 5 10 15 20 25 30 35

Distance from tunnel axis (m)

Sur

face

set

tlem

ent (

mm

)

2-D FE analysisMeasure data (Test 1, Greenfield, VL = 1%)

TUNNEL

Surface settlement

(a)

0

5

10

15

20

-40-30-20-100

Soil settlement on tunnel axis (mm)

Dep

th (m

.b.g

.l.)

25

2-D FE analysisMeasured data (Test 1, Greenfield, VL=1%)

TUNNEL

Settlement along tunnel axis

0

5

10

15

20

25

-8-6-4-20

Lateral soil movement at 5.5m from tunnel axis (mm)

Dep

th (m

.b.g

.l.)

2-D FE analysisMeasured data (Test 1, Greenfield, VL=1%)

TUNNEL

Horizontal soil movement at 5.5m from tunnel axis

5.5m

Tunnel springlineTunnel springline

(b) (c)

Figure F.2 Comparison between predicted and measured greenfield soil movement of Test 1 (a) Surface settlement (b) Subsurface lateral soil movement (c) Subsurface soil

settlement

359

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

00.33 0.46 0.63 1.00 1.50

Pile stiffness modification factorP

ile h

ead

settl

emen

t (m

m)

Test 1 - Single pile

0

5

10

15

20

25

-6-5-4-3-2-10Pile lateral deflection (mm)

Dep

th (m

.b.g

.l.)

2-D factor = 0.3302-D factor = 1.0002-D factor = 1.5002-D factor = 0.4602-D factor = 0.628Measured data (Test 1, Single pile)

TEST 11340KN

TUNNE

Measured

Measured

Tunnel springline

Tunn

el

Tunnel springline

L

(a) (b)

Figure F.3 Comparison between predicted and measured single pile response of Test 1 (a) Pile lateral deflection (b) Pile head settlement

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

00.196 1.000 1.500

Pile stiffness modification factor

Pile

hea

d se

ttlem

ent (

mm

)

Test 1 (Pile group) - Front pile Rear pile

0

5

10

15

20

25

-15-10-50Pile lateral deflection (mm)

Dep

th (m

.b.g

.l.)

2-D factor = 1.0002-D factor = 0.1962-D factor = 1.500Measured data (Test 1, 2x2 pile group, Front)

Rear Front

2.1m

Sym

(a) (b)

Figure F.4 Comparison between predicted and measured pile group response of Test 1 (a) Pile lateral deflection (b) Pile head settlement

360

-15

-10

-5

00 5 10 15 20 25 30 35

Distance from tunnel axis (m)

Sur

face

set

tlem

ent (

mm

)

2-D FE analysisMeasure data (Test 3, Greenfield, VL = 1%)

TUNNEL

Surface settlement

(a)

0

5

10

15

20

25

30

-25-20-15-10-50

Soil settlement on tunnel axis (mm)

Dep

th (m

.b.g

.l.)

2-D FE analysisMeasured data (Test 3, Greenfield, VL=1%)

TUNNEL

Settlement along tunnel axis

0

5

10

15

20

25

30

-6-5-4-3-2-10

Lateral soil movement at 5.5m from tunnel axis (mm)

Dep

th (m

.b.g

.l.)

2-D FE analysisMeasured data (Test 3, Greenfield, VL=1%)

TUNNEL

Horizontal soil movement at 5.5m from tunnel axis

5.5m

Tunnel springlineTunnel springline

(b) (c)

Figure F.5 Comparison between predicted and measured greenfield soil movement of Test 3 (a) Surface settlement (b) Subsurface lateral soil movement (c) Subsurface soil

settlement

361

362

-25

-20

-15

-10

-5

00.15 0.46 1.00 3.00

Pile stiffness modification factor

Pile

hea

d se

ttlem

ent (

mm

)

Test 3 - Single pile

0

5

10

15

20

25

30

-6-4-202Pile lateral deflection (mm)

Dep

th (m

.b.g

.l.)

2-D factor = 1.0002-D factor = 0.4602-D factor = 3.0002-D factor = 0.152Measured data (Test 3, Single pile)

TEST 31340KN

TUNNE

Measured

Measured

Tunnel springline

Tunn

el

Tunnel springlineL

(a) (b)

Figure F.6 Comparison between predicted and measured single pile response of Test 3 (a) Pile lateral deflection (b) Pile head settlement

-40

-35

-30

-25

-20

-15

-10

-5

00.065 0.196 1.000 3.000

Pile stiffness modification factor

Pile

hea

d se

ttlem

ent (

mm

)

Test 3 (Pile group) - Front pile Rear pile

0

5

10

15

20

25

30

-12-10-8-6-4-20Pile lateral deflection (mm)

Dep

th (m

.b.g

.l.)

2-D factor = 0.0652-D factor = 0.1962-D factor = 1.0002-D factor = 3.000Measured data (Test 3, 2x2 pile group, Front)

Rear Front

2.1m

Sym

(a) (b)

Figure F.7 Comparison between predicted and measured pile group response of Test 3 (a) Pile lateral deflection (b) Pile head settlement