한국지반공학회논문집 (Journal of the Korean Geotechnical Society)

한국지반공학회 (Korean Geotechnical Society)
권호 표지
DOI QR코드

DOI QR Code

콘관입으로 인한 과압밀점토의 과잉간극수압의 분포

Excess Pore Pressure Induced by Cone Penetration in OC Clay

  • 김태준 (쌍용건설㈜ 토목기술부) ;
  • 김상인 (고려대학교 사회환경시스템공학과) ;
  • 이우진 (고려대학교 사회환경시스템공학과)
  • 발행 : 2006.11.30
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

본 논문에서는 과압밀된 점토에서 피에조콘 관입으로 인한 과잉간극수압의 공간적인 분포를 알아내기 위한 대형 토조시험을 실시하고 분석결과를 제시하였다. 시험결과에 의하면 콘 주변의 전단영역에서 과잉간극수압은 콘 표면으로부터 전단영역의 경계까지 직선적으로 증가하며, 소성영역에서는 대수적으로 감소하여 소성영역 경계에서 영으로 접근하였다. 또한 전단영역의 크기는 콘 반경의 2.2-1.5배 정도이며 과압밀비 증가 시 전단영역의 크기는 감소하는 반면 소성영역의 크기는 과압밀비에 상관없이 콘 반경의 약 11배로 일정하였다. 본 연구에서는 변형률 속도와 응력이 방성 효과를 고려하여 MCC(Modified Cam Clay) 모델과 공동확장이론으로부터 피에조콘 위치에서의 과잉간극수압을 예측하였으며, 전단영역에서 ${\Delta}u_{shear}$의 선형증가와 전단 및 소성영역에서 ${\Delta}u_{oct}$의 대수적 감소를 가정하여 과잉간극수압의 공간적 분포를 예측하기 위한 방법을 제시하였다. 이러한 방법으로 예측된 간극수압의 분포는 대형 토조시험에서의 콘 관입시험 결과와 비교를 통해 검증되었다.

A series of calibration chamber tests are performed to investigate the spatial distribution of the excess porewater pressure due to piezocone penetration into overconsolidated clays. It was observed that the excess porewater pressure increases monotonically from the piezocone surface to the outer boundary of the shear zone and then decreases logarithmically, approaching zero at the outer boundary of the plastic zone. It was also found that the size of the shear zone decreases from approximately 2.2 to 1.5 times the cone radius with increasing OCR, while the plastic radius is about 11 times the piezocone radius, regardless of the OCR. Based on the modified Cam clay model and the cylindrical cavity expansion theory, the expressions to predict the Initial porewater pressure at the piezocone were developed, considering the effects of the strain rate and stress anisotropy. The method of predicting the spatial distribution of excess porewater pressure proposed in this study was verified by comparing it with the porewater pressure measured in overconsolidated specimens in the calibration chamber.

키워드

참고문헌

  1. Abu-Farsakh, M. Y., Voyiadjis, G. Z., and Tumay, M. T. (1998), 'Numerical Analysis of the Miniature Piezocone Penetration Tests in Cohesive Soils', International Journal for Numerical and Analytical Methods on Geomechanics, Vol.22, pp.791-818 https://doi.org/10.1002/(SICI)1096-9853(1998100)22:10<791::AID-NAG941>3.0.CO;2-6
  2. Baligh, M. M. and Levadoux, J. N. (1980), 'Pore Pressure Dissipation after Cone Penetration', Report R80-11, Massachusetts Institute of Technology, Cambridge, Mass
  3. Baligh, M. M. and Levadoux, J. N. (1986), 'Consolidation after Undrained Piezocone Penetration. II: Interpretation', Journal of Geotechnical Engineering, ASCE, Vol.112, No.7, pp.727-745 https://doi.org/10.1061/(ASCE)0733-9410(1986)112:7(727)
  4. Bond, A. J. and Jardine, R. J. (1991), 'Effects of Installing Displacement Piles in a High OCR Clay', Geotechnique, Vol.41, No.3, pp.341-363 https://doi.org/10.1680/geot.1991.41.3.341
  5. Bums, S. E. and Mayne, P. W. (1998), 'Monotonic and Dilatory Pore-Pressure Decay during Piezocone Tests in Clays', Canadian Geotechnical Journal, Vol.35, No.6, pp.1063-1073 https://doi.org/10.1139/cgj-35-6-1063
  6. Campanella, R. G., Robertson, P. K., and Gillespie, D. (1986), 'Factor affecting the Porewater Pressures and its Measurements Around a Penetrating Cone', 39th Canadian Geotechnical Conference, Ottawa, pp.291-299
  7. Cao, L. F., Teh, C. I., and Chang, M. F. (2001), 'Undrained Cavity Expansion in Modified Cam Clay I: Theoretical Analysis', Geotechnique, Vol.51, No.4, pp.323-334 https://doi.org/10.1680/geot.51.4.323.39395
  8. Chang, M. F., Teh, C. I., and Cao, L. F. (1999), 'Critical State Strength Parameters of Saturated Clays from the Modified Cam Clay Model', Canadian Geotechnical Journal, Vol.36, No.5, pp. 876-890 https://doi.org/10.1139/cgj-36-5-876
  9. Chang, M. F., Teh, C. I., and Cao, L. F. (2001), 'Undrained Cavity Expansion in Modified Cam Clay II: Application to the Interpretation of the Piezocpne Test', Geotechnique, Vol.51, No.4, pp.335-350 https://doi.org/10.1680/geot.51.4.335.39390
  10. Chen, B. S. and Mayne, P. W. (1994), 'Profiling the Overconsolidation Ratio of Clays by Piezocone Tests', Report GIT-CEEGEO-94-1, Georgia Institute of Technology, Atlanta, 280pp
  11. Gupta, R. C. (1983), 'Determination of the In-situ Coefficient of Consolidation and Permeability of Submerged Soils using Electrical Piezoprobe Soundings', Ph.D. Dissertation, University of Florida
  12. Jamiolkowski, M., Ladd, C. C. Germaine, J. T., and Lancellotta, R. (1985), 'New Developments in Field and Laboratory Testing of Soils', 11th International Conference on Soil Mechanics and Foundation Engineering, San Francisco, pp.57-153
  13. Kim, T. J. (2005), 'Dissipation of Porewater Pressure due to Piezocone Penetration in OC Clay', Ph.D. dissertation, Korea University
  14. Konard, J. M. and Law, K. T. (1987), 'Undrained Shear Strength from Piezocone Tests', Canadian Geotechnical Journal, Vol.24, No.3, pp.392-405 https://doi.org/10.1139/t87-050
  15. Kulhawy, F. H. and Mayne, P. W. (1990), 'Manual on Estimating Soil Properties for Foundation Design', Report EPRI EL-6800, Electric Power Research Institute, Palo Alto, C.A
  16. Ladanyi, B. (2002), 'Discussion: Undrained Cavity Expansion in Modified Cam Clay II: Application to the Interpretation of the Piezocone Test', Geotechnique, Vol.52, No.4, pp.307-311 https://doi.org/10.1680/geot.52.4.307.41026
  17. Ladd, C. C. and Foott, R. (1974), 'New Design Procedure for Stability of Soft Clays', Journal of Geotechnical Engineering, ASCE, Vol.100, No.7, pp.763-786
  18. Ladd, C. C., Foott, R., Ishihara, K., Schlosser, F., and Poulos, H. G. (1977), 'Stress Deformation and Strength Characteristic', 9th International Conference on Soil Mechanics and Foundation Engineering, Tokyo, pp.421-494
  19. Lunne, T., Eidsmoen, T. E., Powell, J. J. M., and Quatermann, R. S. T. (1986), 'Piezocone Testing in Overconsolidated Clays', 39th Canadian Geotechnical Conference, Ottawa, pp.209-218
  20. Mayne, P. W. and Bachus, R. C. (1988), 'Profiling OCR in Clays by Piezocone Soundings', International Symposium on Penetration Testing, Rotterdam, Netherlands, pp.857-864
  21. Mitchell, J. K., Guzikowski, F., and Villet, W. C. B. (1978), 'The Measurement of Soil Properties In-Situ', Report W-7405-ENG-48, Lawrence Berkeley Laboratory, University of California, Berkeley, C.A., 67pp
  22. Robertson, P. K. and Campanella, R. G. (1983), 'Interpretation of Cone Penetration Tests. Part II: Clay', Canadian Geotechnical Journal, Vol.20, No.4, pp.734-745 https://doi.org/10.1139/t83-079
  23. Roy, M., Tremblay, M., Tavenas, F., and La Rochelle, P. (1982), 'Development of Pore Pressures in Quasi-Static Penetration Tests in Sensitive Clay', Canadian Geotechnical Journal, Vol.19, No.1, pp.124-138 https://doi.org/10.1139/t82-015
  24. Sully, J. P., Campanella, R. G., and Robertson, P. K. (1988), 'Overconsolidation Ratio of Clays from Penetration Pore Pressures', Journal of Geotechnical Engineering, ASCE, Vol.114, No.2, pp. 209-216 https://doi.org/10.1061/(ASCE)0733-9410(1988)114:2(209)
  25. Teh, C. L. and Houlsby, G. T. (1991), 'An Analytical Study of the Cone Penetration Test in Clay', Geotechnique, Vol.41, No.1, pp.17-34 https://doi.org/10.1680/geot.1991.41.1.17
  26. Torstensson, B. A. (1977), 'The Pore Pressure Probe', Geotechnical Meeting, Norwegian Geotechnical Society, Oslo, pp.34.1-34.15
  27. Vesic, A. S. (1972), 'Expansion of Cavities in Infinite Soil Mass', Journal of the Soil Mechanics and Foundations Division, ASCE, Vol.98, No.3, pp.265-290
  28. Wood, D. M. (1990), Soil Behavior and Critical State Soil Mechanics, Cambridge University Press, Cambridge, UK
  29. Wroth, C. P. (1984), 'The Interpretation of In-Situ Soil Tests', Geotechnique, Vol.34, No.4, pp.449-489 https://doi.org/10.1680/geot.1984.34.4.449
  30. Wroth, C. P., Carter, J. P., and Randolph, M. F. (1979), 'Stress Change around a Pile Driven into Cohesive Soil', Recent Developments in the Design and Construction of Piles, I.C.E, London, pp.255-264