Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Analysis of Load Sharing Ratio of Piled Raft Foundation by Field Measurement

현장 계측을 통한 말뚝지지 전면기초의 하중분담률 분석

  • 정상섬 (연세대학교 토목환경공학과) ;
  • 이준환 (연세대학교 토목환경공학과) ;
  • 박종전 (연세대학교 토목환경공학과) ;
  • 노양훈 (연세대학교 토목환경공학과) ;
  • 홍문현 (연세대학교 토목환경공학과)
  • Received : 2017.08.02
  • Accepted : 2017.08.23
  • Published : 2017.08.31
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Abstract

In this study, field measurements were investigated to analyze the load sharing ratio and behavior of piled raft foundation. The field measurements were performed for about 300 days from the start of construction. The geometry of the raft is $3.1m{\times}3.1m$, and the pre-cast and pre-bored pile is 23 m in length and 0.508 m in diameter. Based on the field measurements, the load-settlement relationship of the piled raft foundation was obtained, and the load sharing ratio of the pile was converged to 70% at ultimate loading condition. The load sharing ratio of the pile increased as the settlement increased, and this is because the surface friction of the weathered soil, which is at the lower ground, was significantly increased. Based on the results of the field measurements, load transfer curves were obtained and applied to a numerical analysis by using load transfer method.

본 연구에서는 말뚝지지 전면기초의 하중분담률 및 거동분석을 위해 시공단계 별 현장계측을 수행하였다. 현장계측은 시공시작일 부터 약 300일 동안 수행되었으며, 사용된 말뚝지지 전면기초는 $3.1m{\times}3.1m$ 크기의 전면기초와 길이 23m 직경 0.508m의 매입말뚝 5본이 시공되었다. 현장계측을 통해 시공단계에 따라 말뚝지지 전면기초의 하중-침하량 관계를 확인할 수 있었고, 극한하중조건에서 말뚝의 하중분담률은 약 70%에 수렴하였다. 기초의 침하량이 증가함에 따라 말뚝의 하중분담률이 증가하는 경향을 보였으며, 이는 하부 지반인 풍화토의 주면마찰력이 크게 영향을 주었기 때문으로 판단된다. 현장계측 결과를 이용하여 하중전이분석을 수행하였으며, 이를 통해 말뚝-지반 사이의 비선형 하중전이곡선을 산정하고 하중전이기법을 이용한 수치해석 결과에 적용하였다.

Keywords

References

  1. Brown, P. T. and Weisner, T. J. (1975), "The Behaviour of Uniformly Loaded Piled Strip Footings", Soils and Foundations, Vol.15, No.4, pp.13-21. https://doi.org/10.3208/sandf1972.15.4_13
  2. Burland, J. B., Broms, B. B., and De Mello, V.F.B. (1977), "Behaviour of Founadations and Structures", Proceedings of 9th International Conference on Soil Mechanics and Foundation Engineering, Tokyo, Vol.2, pp.495-549.
  3. Cho, J. Y. and Jeong, S. S. (2012), "Development of Threedimensional Approximate Analysis Method for Piled Raft Foundations", Journal of the Korean Geotechnical Society, Vol.28, No.4, pp. 67-78. https://doi.org/10.7843/kgs.2012.28.4.67
  4. Chow, Y. K. and The, C. I. (1991), "Pile-Cap-Pile-Group Interaction in Nonhomogeneous Soil", Journal of Geotechnical Engineering, Vol.117, No.11, pp.1655-1668. https://doi.org/10.1061/(ASCE)0733-9410(1991)117:11(1655)
  5. Clancy, P. and Randolph, M. F. (1993), "An Approximate Analysis Procedure for Piled Raft Foundations", International Journal for Numerical and Analytical Methods in Geomechanics, London, Vol.17, No.12, pp.849-869. https://doi.org/10.1002/nag.1610171203
  6. Cooke, R. W., Bryden Smith, D. W., Gooch, M. N., and Sillet, D. F. (1981), "Some Observations of the Foundation Loading and Settlement of a Multi-storey Building on a Piled Raft Foundation in London Clay", Proceedings. I.C.E., part 1, 70, pp.433-460.
  7. de Sanctis, L. and Mandolini, A. (2003), "On the Ultimate Vertical Load of Piled Rafts on the Soft Clay Soils", Proceedings of 4th International Geotechnical Seminar on Deep Foundation on Bored and Auger Piles, Ghent, Millpress, Rotterdam, pp.379-386.
  8. Hain, S. J. and Lee, I. K. (1978), "The Analysis of Flexible Raftpile Systems", Geotechnique, Vol.28, No.1, pp.65-83. https://doi.org/10.1680/geot.1978.28.1.65
  9. Hooper, J. A. (1979), "Review of Behaviour of Piled Raft Foundations", CIRIA report $n^{\circ}$ 83.
  10. Horikoshi, K. and Randolph, M. F. (1996), "Centrifuge Modelling of Piled Raft Foundations on Clay", Geotechnique, Vol.47, No.5, pp.741-752.
  11. Jendeby, L. (1986), "Friction Piled Foundations in Soft Clay. A Study of Load Transfer and Settlements", Ph.D. Thesis, Dept. Geotech. Eng. Chalmers University of Tech, Goteborg
  12. Jeong, S. S., Lee, J. H., and Lee, C. J. (2004), "Slip Effect at the Pile-soil Interface on Dragload", Computers & Geotechnics, Vol.31, pp.115-126. https://doi.org/10.1016/j.compgeo.2004.01.009
  13. Katzenbach, R., Arslan, U., and Moormann, C. (2000), "Piled Raft Foundations Projects in Germany", Design applications of raft foundations, Hemsley, J. A. Editor, Thomas Telford, pp.323-392.
  14. Katzenbach, R., Schmitt, A., and Turek, J. (2005), "Assessing Settlement of High-rise Structures by 3D Simulations", Computer-Aided Civil and Infrastructure Engineering.
  15. Kitiyodom, P. and Matsumoto, T. (2003), "A Simplified Analysis Method for Piled Raft Found Ations in Non-homogeneous Soils", International Journal for Numerical and Analytical Methods in Geomechanics, 27, pp.85-109. https://doi.org/10.1002/nag.264
  16. Kuwabara, F. (1989), "An Elastic Analysis for Piled Raft Foundations in a Homogeneous Soil", Soils and Foundations. Vol.28, No.1, pp.82-92.
  17. Kim, H. T., Kang, I. K., Park, J. J., and Park, S. K. (2002), "Laboratory Model Tests on Load Sharing Characteristics of Piled Raft Foundations Applied Vertical Loads on Sandy Soils", Journal of the Korean Society of Civil Engineers, Vol.22, No.2, pp.111-120.
  18. Kwon, O. K., Oh, S. B., and Kim, J. B. (2005), "Experimental Study on the Load Sharing Ratio of Group Pile", Journal of the Korean Geotechnical Society, Vol.21, No.5, pp.51-58.
  19. Lee, I. K. (1993), "Analysis and Performance of Raft and Raft-pile Foundations in a Homogeneous Soil", Proceedings of 3rd International Conference on Case History in Geotechnical Engineering, St Louis (also Research Report R133, ADFA, University of New South Wales, Australia).
  20. Lee, J. H. and Jeong, S. S. (2007), "Three Dimensional Numerical Analysis of Piled Raft on Soft Clay", Journal of the Korean Geotechnical Society, Vol.23, No.5, pp.63-75.
  21. Lee, J. H., Kim, Y. H., and Jeong, S. S. (2010), "Three-dimensional Analysis of Bearing Behavior of Piled Raft on Soft Clay", Computers & Geotechnics, Vol.37, pp.103-114. https://doi.org/10.1016/j.compgeo.2009.07.009
  22. Lee, S. H., Park, Y. H., and Song, M. J. (2007), "A Paractical Analysis Method for the Design of Piled Raft Foundations", Journal of the Korean Geotechnical Society, Vol.23, No.12, pp. 83-94.
  23. Mandolini, A., Russo, G., and Viggiani, C. (2005), "Piled Foundations: Experimental I Nvestigations, Analysis and Design", State-of-the-Art Rep. Proc., 16th ICSMGE, Osaka, Japan, Vol.1, pp.177-213.
  24. Ottaviani, M. (1975), "Three-Dimensional Finite Element Analysis of Vertically Loaded Pile Groups", Geotechnique, 25, pp.159-174. https://doi.org/10.1680/geot.1975.25.2.159
  25. Park, D. G., Choi, K. J., Kim, D. W., Chung, M. K., and Lee, J. H. (2012), "Analysis of Piled Raft Capacity Increase with Centrifuge Test", Journal of the Korean Geotechnical Society, Vol.28, No.8, pp.43-53. https://doi.org/10.7843/kgs.2012.28.8.43
  26. Poulos, H. G. (1991), "Analysis of Piled Strip Foundations", Proceedings of Conference on computer methods and advances in geomechanics, Rotterdam: Balkema, pp.183-191.
  27. Poulos, H. G. (1994), "An Approximate Numerical Analysis of Pile-raft Interaction", International Journal for Numerical and Analytical Methods in Geomechanics, London, Vol.18, No.2, pp. 73-92. https://doi.org/10.1002/nag.1610180202
  28. Poulos, H. G. (2001), "Piled Raft Foundations: Design and Applications", Geotechnique, 51, pp.95-113. https://doi.org/10.1680/geot.51.2.95.40292
  29. Randolph, M. F. (1983), "Design of Piled Foundations", Research Report Soils TR143. Cambridge: Cambridge University Engineering Department.
  30. Randolph, M. F. (1994), "Design Methods for Pile Groups and Piled Rafts", Proceedings of 13th ICSMFE, New Delhi, India, Vol.5, pp.61-82.
  31. Reul, O. and Randolph, M. F. (2003), "Piled Rafts in Overconsolidated Clay-Comparison of In-situ Measurements and Numerical Analyses", Geotechnique, Vol.53, No.3, pp.301-315. https://doi.org/10.1680/geot.2003.53.3.301
  32. Roh, Y. H. (2017), "Load Carrying Behavior of Piled Rafts with Varying Ground Water Level and Bed Rock Inclination", Master's Thesis, Yonsei university, Seoul.
  33. Sommer, H., Tamaro, G., and De Benedittis, C. (1991), "Messe Turm, Foundations for the Tallest Building in Europe", Proceedings. 4th International Conf. on Piling and Deep Foundations, Stresa, Balkema, Rotterdam, pp.139-145.
  34. Wang, A. (1996), "Three Dimensional Finite Element Analysis of Pile Groups and Piled-raft", Ph.D. dissertation, University of Manchester, U.K.
  35. Won, J. O. and Jeong, S. S. (2005), "Nonlinear Three-dimensional Analysis of Piled Piers Considering Coupled Cap Rigidities", Journal of the Korean Geotechnical Society, Vol.21, No.6, pp. 19-30.
  36. Won, J. O., Jeong, S. S., Lee, J. H., and Jang, S. Y. (2006), "Nonlinear Three-dimensional Analysis of Pile Group Supported Columns Considering Pile Cap Flexibility", Computers & Geotechnics, Vol.33, pp.355-370. https://doi.org/10.1016/j.compgeo.2006.07.007
  37. Yamashita, K., Kakurai, M., Yamada, T., and Kuwabara, F. (1993), "Settlement Behaviour of a Five Storey Building on a Piled Raft Foundation", Proceedings. II Seminar on Deep Foundations on Bored and Auger Piles, Van Impe W.Editor, pp.351-356.
  38. Zhang, G. M., Lee, I. K., and Zhao, X. H. (1991), "Interactive Analysis of Behaviour of Raft-pile Foundations", Proceedings of Geo-Coast' 91, Yokohama2, pp.759-764.