KSCE Journal of Civil and Environmental Engineering Research (대한토목학회논문집)

Korean Society of Civil Engeneers (대한토목학회)
권호 표지
DOI QR코드

DOI QR Code

The Response of a Single Pile and Pile Groups to Tunnelling Performed in Weathered Rock

풍화암에서 실시된 터널굴착으로 인한 단독말뚝 및 군말뚝의 거동

  • Received : 2012.06.14
  • Accepted : 2012.08.17
  • Published : 2012.09.15
Download PDF
⟨ Previous Next ⟩

Abstract

The effects of tunnelling in weak weathered rock on the behaviour of a pre-existing single pile and pile groups ($3{\times}3$ and $5{\times}5$ pile groups) above a tunnel have been studied by carrying out three-dimensional (3D) elasto-plastic numerical analyses. Numerical modelling of such effects considers the response of the single pile and pile groups in terms of tunnelling-induced ground and pile settlement as well as changes of the shear transfer mechanism at the pile-soil interface due to tunnelling. Due to changes in the relative shear displacement between the pile and the soil at the pile-soil interface with tunnel advancement, the shear stresses and axial pile force distributions along the pile change drastically. Based on the computed results, upward shear stresses are induced up to about Z/L=0.775 from the pile top, while downward shear stresses are mobilised below Z/L=0.775, resulting in a reduction in the axial pile force distribution with depth equivalent to a net increase in the tensile force on the pile. A maximum tensile force of about $0.36P_a$ developed on the single pile solely due to tunnelling, where $P_a$ is the service axial pile loading prior to tunnelling. The degree of interface shear strength mobilisation at the pile-soil interface was found to be a key factor governing pile-soil-tunnelling interaction. Overall it has been found that the larger the number of piles, the greater is the effect of tunnelling on the piles in terms of pile settlement, while changes of the axial pile forces for the piles in the groups are smaller than for a single pile due to the shielding effect. The reduction of apparent allowable pile capacity due to tunnelling-induced pile head settlement was significant, in particular for piles inside the groups.

본 연구에서는 3차원 탄-소성 유한차분해석을 통해 기존재하는 단독말뚝, $3{\times}3$및 $5{\times}5$ 군말뚝의 바로 아래 풍화암 지반에서 실시된 터널시공으로 인한 말뚝의 거동을 분석하였다. 수치해석에서는 터널굴착으로 인한 말뚝의 거동을 규명하기 위하여 지반/말뚝의 침하 및 전단응력전이(shear stress transfer) 메커니즘을 심도있게 분석하였다. 터널굴착으로 유발된 지반의 침하와 말뚝-지반 사이 경계면에서의 상대변위 발생으로 인해 말뚝에 작용하는 전단응력 및 축력의 분포가 매우 크게 변화하였다. 계산된 결과에 의하면 터널굴착으로 인해 말뚝의 두부로부터 말뚝길이의 약 80%에 해당되는 위치까지는 상향의 전단응력이 발생하였고, 그 하부에서는 하향의 전단응력이 발생하였다. 이로 인해 말뚝의 축력이 터널의 굴착에 따라 지속적으로 감소하고, 순수한 터널의 시공으로 인하여 말뚝에는 인장력이 발생하였는데 이로 인해 말뚝에는 최대 $0.36P_a$의 인장력이 발생하였다, 여기서 $P_a$는 터널굴착이전에 말뚝두부에 작용하는 설계하중이다. 말뚝의 거동은 경계면에서의 전단강도 발현 정도에 가장 큰 영향을 받는 것으로 나타났다. 군말뚝의 경우 일반적으로 말뚝의 숫자가 증가할수록 터널의 시공에 의해 말뚝의 침하가 증가하는 것으로 나타났으며, 이와는 반대로 말뚝의 축력변화는 군효과(shielding effect)로 인해 단독말뚝의 경우에 비해 작은 것으로 분석되었다. 터널굴착으로 인한 말뚝침하의 증가로 인한 겉보기지지력(apparent pile capacity) 감소는 단독말뚝에 비해 군말뚝에서 두드러지는 것으로 분석되었다.

Keywords

References

  1. 이인모(2004) 터널의 지반공학적 원리, 새론.
  2. 이철주(2009) Soil slip을 고려한 터널굴착에 의한 단독말뚝의 거동연구, 한국지반환경공학회 논문집, 한국지반환경공학회, 제 10권 제5호, pp. 59-67.
  3. Bakker, K. J. and Bezuijen, A. (2008) Ten years of bored tunnels in the Netherlands, Geotechniek, April, 6-13.
  4. Chapman, D., Metje, N., and Stärk, A. (2010) Introduction to tunnel construction, Spon Press.
  5. Chen, C. Y. and Martin, G. R. (2001) Effect of embankment slope on lateral response of piles, Flac and Numerical Modelling in Geomechanics, Billaux et al. (eds), Swets & Zeitlinger, pp. 205-213.
  6. Chen, L. T., Poulos, H. G., and Loganathan, N. (1999) Pile responses caused by tunnelling. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol 125, No. 3, pp. 207-215. https://doi.org/10.1061/(ASCE)1090-0241(1999)125:3(207)
  7. Cheng, C. Y., Dasari, G. R., Chow, Y. K., and Leung, C. F. (2007) Finite element analysis of tunnel-soil-pile interaction using displacement controlled model. Tunnelling and Underground Space Technology, Vol. 22, pp. 450-466. https://doi.org/10.1016/j.tust.2006.08.002
  8. Davisson, M. T. (1972) High capacity piles. Proceedings of Lecture Series in Innovations in Foundation Construction, ASCE, Illinois Section, pp. 81-112.
  9. Devriendt, M. and Williamson, M. (2011) Validation of methods for assessing tunnelling-induced settlements on piles, Ground Engineering, March, 25-30.
  10. Fleming, W. G. K., Weltman, A. J., Randolph, W. F., and Elson, W. K. (1992) Piling engineering, 2nd Edition, Blackie Academic & Professional.
  11. Huang, M., Zhang, C., and Li, Z. (2009) A simplified analysis method for the influence of tunnelling on grouped piles. Tunnelling and Underground Space Technology, Vol. 24, pp. 410- 422. https://doi.org/10.1016/j.tust.2008.11.005
  12. Itasca Consulting Group. (2006) FLAC3D - Fast Lagrangian Analysis of Continua user's and theory manuals, Minneapolis, Minn
  13. Jacobsz, S.W. (2002) The effects of tunnelling on piled foundations. PhD thesis, University of Cambridge.
  14. Jacobsz, S.W. (2003) Tunnelling effects on piled foundations. Tunnels and Tunnelling international, June, 28-31.
  15. Kaalberg, F.J., Teunissen, E.A.H., van Tol A.F., and Bosch, J.W. (2005) Dutch Research on the impact of shield tunneling on pile foundations. Geotechnical Aspects of Underground Construction in Soft Ground, Proceedings of 5th International Conf. of TC 28 of the ISSMGE, pp. 123-133.
  16. Kitiyodom, P., Matsumoto, T., and Kawaguchi, K. (2005) A simplified analysis method for piled raft foundations subjected to ground movements induced by tunneling. Int. J. Numer. Anal. Meth. Geomech. Vol. 29, pp. 1485-1507. https://doi.org/10.1002/nag.469
  17. Lee, C. J. (2001) The influence of negative skin friction on piles and in pile groups. PhD thesis, Cambridge University.
  18. Lee, C. J. and Jacobsz, S.W. (2006) The Influence of Tunnelling on Adjacent Piled Foundations, Tunnelling and Underground Space Technology, Vol. 21, Issues 3-4, p. 430 https://doi.org/10.1016/j.tust.2005.12.072
  19. Lee, C. J. and Chiang, K. H. (2007) Responses of single piles to tunneling-induced soil movements in sandy ground. Canadian Geotechnical Journal, Vol. 44, pp. 1224-1241. https://doi.org/10.1139/T07-050
  20. Lee, C. J. (2012) Numerical analysis of the interface shear transfer mechanism of a single pile to tunnelling in weathered residual soil, Comput. Geotech, Vol. 42, pp. 193-203. https://doi.org/10.1016/j.compgeo.2012.01.009
  21. Lee, G.T.K. and Ng, C.W.W. (2005) The 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. https://doi.org/10.1061/(ASCE)1090-0241(2005)131:2(193)
  22. Lee, S. W., Choy, C.K.M., Cheang, W.W. L., Swolfs, W., and Brinkgreve, R. (2010) Modelling of tunnelling beneath a building supported by friction bored piles. The 17th Southeast Asian Geotechnical Conference, pp. 215-218.
  23. Lee, Y. J. (2004) Tunnelling adjacent to a row of loaded piles. PhD Thesis, University College London, University of London.
  24. Loganathan, N. and Poulos, H.G. (1998) Analytical prediction for tunneling-induced ground movement in clays. J. Geotech. Geoenviron. Eng., ASCE, Vol. 124, No. 9, pp. 846-856. https://doi.org/10.1061/(ASCE)1090-0241(1998)124:9(846)
  25. Loganathan, N., Poulos, H.G. and Stewart, D.P. (2000) Centrifuge model testing of tunneling-induced ground and pile deformations. Geotechnique, Vol. 50, No 3, pp. 283-294. https://doi.org/10.1680/geot.2000.50.3.283
  26. Loganathan N., Poulos, H. G., and Xu, K. J. (2001) Ground and pile-group responses due to tunneling. Soils and Foundations, Vol. 41, pp. 57-67.
  27. Mair, R.J. and Taylor, R.N. (1997) Theme lecture: bored tunnels in the urban environment. Proc. 14th International Conference on Soil Mechanics and Foundation Engineering, Hamburg, Balkema, Vol. 4, pp. 2353-2385.
  28. Mroueh, H. and Shahrour, I. (2002) Three-dimensional finite element analysis of the interaction between tunnelling and pile foundation. Int. J. Numer. Anal. Meth. Geomech. Vol. 26, pp. 217-230. https://doi.org/10.1002/nag.194
  29. Ong, O.W., Leung, C.F., Yong, K.Y., and Chow, Y.K. (2006) Pile responses due to tunneling in clay. Physical Modelling in Geotechnics, 6th International Conference on Physical Modelling in Geotechnics, Taylor & Francis Group, London, pp. 1177- 1182.
  30. Pang, C. H. (2006) The effects of tunnel construction on nearby pile foundation. PhD thesis, The National University of Singapore, pp. 27-56.
  31. Selemetas, D. (2005) The response of full-scale piles and piled structures to tunnelling. PhD thesis, University of Cambridge.
  32. Xu, K.J. and Poulos, H.G. (2001) 3-D elastic analysis of vertical piles subjected to ''passive" loadings. Comput. Geotech. Vol. 28, pp. 349-375. https://doi.org/10.1016/S0266-352X(00)00024-0
  33. Zhang, L.M., Ng, C.W.W. and Lee, C.J. (2004) Effects of slope and sleeving on the behavior of laterally loaded piles, Soils and Foundation, Vol. 44, No. 4, pp. 99-108. https://doi.org/10.3208/sandf.44.4_99

Cited by

  1. A study on the effect of tunnelling to adjacent single piles and pile groups considering the transverse distance of pile tips from the tunnel vol.17, pp.6, 2015, https://doi.org/10.9711/KTAJ.2015.17.6.637
  2. A study on the effect of the locations of pile tips on the behaviour of piles to adjacent tunnelling vol.17, pp.2, 2015, https://doi.org/10.9711/KTAJ.2015.17.2.091
  3. A study on soil behaviour due to tunnelling under embedded pile using close range photogrammetry vol.18, pp.4, 2016, https://doi.org/10.9711/KTAJ.2016.18.4.365