Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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An Analysis of the Settlement Behavior of Soft Clayey Ground Considering the Effect of Creep during the Primary Consolidation

1차압밀과정중의 크리프의 영향을 고려한 연약 점성토지반의 침하거동 해석

  • 백윈진 (전남대학교 생물산업공학과) ;
  • 송전전 (일본 야마구치대학교 사회건설공학과) ;
  • 최우정 (원광대학교 토목환경공학과) ;
  • 김찬기 (대진대학교 공과대학 건설시스템공학과) ;
  • 송병관 (전남대학교 지역.바이오시스템 공학과)
  • Published : 2008.05.31
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Abstract

This paper is performed to examine the effect of creep during the primary consolidation and the applicability of the Yin's EVP (Elasto-Visco-Plastic) model. In ordinary consolidation theories using the elastic model, the primary consolidation process can be expressed but the secondary consolidation process cannot. It is due to the viscosity, which can express the secondary consolidation, and is sometimes related to the scale effect (difference of the thickness of clay layer between laboratory sample and field condition) such as hypotheses Type A and Type B shown by Ladd et al. (1977). Usually, the existence of the creep during the primary consolidation has been conformed and the Type B is well acceped. On the other hand, from the large-scaled consolidation tests the intermediate characteristic between Type A and Type B was proposed as Type C by Aboshi (1973). In this study, to clarify the effect of creep on the settlement-time relation during the primary consolidation in detail, Type B consolidation tests were performed using the separate-type consolidation test apparatus for a peat and clay. Then the test results were analyzed by using Yin's EVP Model (Yin and Graham, 1994). In conclusion, followings were obtained. At the end of primary consolidation, the compression for the subspecimens should not be the same because of the difference of the excess pore water pressure dissipation rate. And the average settlement measured by the separate-type consolidometer coincides with the analyzed one using the Yin's EVP model. As for the dissipation of the excess pore water pressure, however, the measured excess pore water pressure dissipates faster compared with the Yin's model.

본 연구는 1차압밀 중의 크리프의 영향과 Yin이 제안한 탄-점-소성 모델에 대한 적용성을 검토하였다. 탄성모델을 이용한 일반적인 압밀이론은, 1차압밀 과정을 표현할 수 있으나 2차압밀을 표현할 수 없다. 이러한 결과는 2차압축을 표현할 수 있는 점성에 기인하며, 때로는 Ladd 등(1977)이 제안한 가정 A 및 B와 같은 스케일효과(실험실 공시체와 현장조건 사이의 점토층 두께의 차이)와 관련되어진다. 통상적으로 1차압밀 중의 크리프의 존재는 많은 연구자에 의해 확인되어졌으며, 가정 B가 잘 맞는 것으로 되어있다. 한편, 대형압밀시험을 통해 가정 A와 B의 중간적인 특성이 Aboshi(1973)에 의한 가정 C로써 제안되어졌다. 본 연구에서는 1차압밀 중의 침하-시간관계에 대한 크리프의 영향을 명백히 하기 위해, peat와 점토에 대해 분할형 압밀시험기를 이용하여 가정 B의 압밀시험을 행하였다. 그리고 Yin의 탄-점-소성 모델을 이용하여 실험결과를 해석하였다. 얻어진 결과는 다음과 같다. 1차압밀 종료시에 분할 공시체의 압축은 과잉간극수압 소산속도의 차이에 의해 동일하지 않았다. 또한 분할형 압밀시험기에 의해 측정된 평균변형률과 Yin의 EVP 모델을 이용한 해석치는 잘 일치하였다. 그러나 과잉간극수압의 소산에 대해서는 측정치가 Yin 모델에 비해 빨리 소산되었다.

Keywords

References

  1. 小林正一(1999), "層別計測による泥炭の圧密特性に関する基礎 的研究", 修士論文, 山口大学理工学研究科
  2. 松田博, 白元珍, 白宗和(2006), "一次圧密中の粘土のクリープ に関する一考察", 日本土木学会中国支部 第58回研究発表会論文 集, pp.876-878
  3. Aboshi, H. (1973), "An experimental invesitigation on the similitude in the consolidation of a soft clay, including the secondary creep settlement", 8th ICSMFE, 8
  4. Aboshi, H., Matsuda, H. and Okuda, M. (1981), "Preconsolidation by separate-type consolidometer", Proceedings of 11th ICSMFE, 3, pp.577-580
  5. Baek, W., Moriwaki, T. and Sasaki, Y. (2006), "Numerical analyses on consolidation of clayey ground improved by vertical drain system based on 3-D Elasto-Viscous model", Soils and Foundations, Vol.46, No.2, pp.159-172 https://doi.org/10.3208/sandf.46.159
  6. Barden, L. and Younan, N. A. (1969), "Consolidation of layered clays", Canadian Geotechnique Journal, Vol.6, pp.413-429 https://doi.org/10.1139/t69-042
  7. Ladd, C. C., Foott, R., Ishihara, K., Schosser, F. and Poulos, H. J. (1977), "Stress-deformation and strength characteristics", Proc. 9th ICSMFE, Tokyo 2, State of the are report, pp.421-494
  8. Matsuda, H., Baek, WJ, Baek, JH, Sutou, Y. and Sato, H. (2007), "Effect of creep on the settlement-time relation during primary consolidation of clay", Int. Workshop on Constitutive Modelling- Development, Implementation, Evaluation & Application
  9. Mesri, G., Lo, D.O.K and Feng, T. W. (1994), "Settlement of embankment on soft clays", Proc. of Settlement 94, Vol.1, pp.8-56
  10. Taylor, D. W. and Merchant W. (1940), "A theory of clay consolidation accounting for secondary compression", Journal of Mathematics and Physics, Vol.19, pp.167-185 https://doi.org/10.1002/sapm1940191167
  11. Taylor, D. W. (1948), "Fundamentals of soil mechanics", John Wiley & Sons, pp.208-249
  12. Yin, J. H. and Graham, J. (1994), "Equivalent times and onedimensional elastic visco-plastic modeling of time-dependent stressstrain behavior of clays", Canadian Geotechnique Journal, Vol.31, pp.42-52 https://doi.org/10.1139/t94-005
  13. Yin, J. H. and Graham, J. (1996), "Elastic visco-plastic modeling of one-dimensional consolidation", Geotechnique, Vol.46, No.3, pp.515-527 https://doi.org/10.1680/geot.1996.46.3.515
  14. Yoshikuni, H., Kusakabe, O., Hirao, T. and Ikegami, S. (1994), "Elasto-Viscous modeling of time-dependent behavior of clay", Proc. of the 13th ICSMFE, New Delhi, India, Vol.1, pp.417-420