Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
권호 표지
DOI QR코드

DOI QR Code

Undrained Shear Behavior of Sandy Soil Mixtures

사질혼합토의 비배수 전단거동 특성

  • Kim, Ukgie (Korea Institute of Construction Technology) ;
  • Ahn, Taebong (Department of Civil & Railroad Engineering, Woosong University)
  • Received : 2010.11.09
  • Accepted : 2011.07.11
  • Published : 2011.08.01
Download PDF
⟨ Previous Next ⟩

Abstract

In the part of geotechnical engineering, soils are classified as either the coarse grained soil or the fine-grained soil following the fine content($F_c$=50%) according to the granularity, and appropriate design codes are used respectively to represent their mechanical behaviour. However, sand-clay mixtures, which are typically referred to as intermediate soils, cannot be easily categorized as either sand or clay. In this study, several monotonic undrained shear tests were carried out on Silica sand fine mixtures with various proportions, and a wide range of soil structures, ranging from one with sand dominating the soil structure to one with fines controlling the behaviour, were prepared using compaction method or pre-consoldation methods in prescribed energy. The shear strength of mixtures below the threshold fines content is observed that as the fines content increases, maximum deviator stress ratio decrease for dense samples while an increase is noted for loose samples. Then, by using the concept of fines content and granular void ratio, the monotonic shear strength of the mixtures was estimated. It was found that the shear behavior of mixtures is greatly dependent on the skeleton structure of sand particles.

지반공학에서 흙은 흙 입자에 의한 세립분 함유율($F_c$=50%)에 따라 모래와 점토로 분류되며, 그들의 역학적 거동에 의해 설계가 이루어진다. 그러나, 모래-점토 혼합토는 일반적으로 intermediate soils로 불리어, 모래나 점토로 쉽게 구분할 수 없다. 본 연구에서는 다양한 비율을 갖는 실리카모래 세립혼합토에 대하여 정적비배수 전단시험을 수행하였고, 미리 계산된 에너지의 다짐방법과 예압밀법을 이용하여 모래부터 점토에 이르는 폭넓은 범위의 흙 구조에 대해 공시체를 준비하였다. 한계 세립함유율 보다 작은 혼합토의 전단강도는 세립분이 증가할수록 증가하며 최대 축차응력비는 조밀한 시료에 대하여 감소하고 느슨한 시료에 대하여 증가한다. 그 후, 골격간극비의 개념을 이용하여 혼합토의 단조 전단강도를 평가하였으며. 이에, 혼합토의 전단강도는 모래입자가 이루는 골격구조에 밀접한 관계가 있음을 알았다.

Keywords

References

  1. Adachi, M., Yasuhara, K. and Shimabukuro, A.(2000), Influences of Sample Preparation Method on the Behavior of Non-plastic Silts in Undrained Monotonic and Cyclic Triaxial Tests, Tsuchito-Kiso, Vol. 48N, No. 11, pp. 24-27(in Japanese).
  2. Chang, N. Y., Yeh, S. T., and Kaufman, L. P.(1982), Liquefaction Potential of Clean and Silty Sands, Proceedings of the 3rd International Earthquake Microzonation Conference, Seattle, USA, Vol. 2, pp. 1017-1032.
  3. Ishihara, K.(1993), Liquefaction and Flow Failure During Earthquakes. Geotechnique, Vol. 43, No. 3, pp. 351-415. https://doi.org/10.1680/geot.1993.43.3.351
  4. Ishihara, K., and Koseki(1989), Discussion on the Cyclic Shear Strength of Fines-containing sands, Earthquakes Geotechnical Engineering, Proceedings of the Eleventh International Conference on Soil Mechanics and Foundation Engineering, Rio De Janiero, Brazil, pp. 101-106.
  5. Kim, U., Hyodo, M., Koga, C. & Orense, R.(2006), Effect of Fines Content on the Monotonic Shear Behavior of Sand-clay Mixtures, Geomechanics and Geotechnics of Particulate Media, pp. 133-138.
  6. Koester, J. P.(1994), The Influence of Fine Type and Content on Cyclic Strength, Ground Failures Under Seismic Conditions, Geotechnical Special Publication, No. 44, ASCE, pp. 17-33.
  7. Matsumoto, K., Hyodo, M. and Yoshimoto, N.(1999), Cyclic Shear Properties of Intermediate Soil Subjected to Initial Shear, Proc., 34th Japan National Conference on Geotechnical Engineering, 637-638(in Japanese)
  8. Naeini, S. A., Baziar, M. H.(2004), Effect of Fines Content on Steady-state Strength of Mixed and Layered Samples of a Sand, Soil Dynamics and Earthquake Engineering 24., pp. 181-187. https://doi.org/10.1016/j.soildyn.2003.11.003
  9. Poulos, S. J., Castro, G. and France, J. W.(1985), Liquefaction Evaluation Procedure, Journal of Geotechnical Engineering, Vol. 111, No. 6, pp. 772-792. https://doi.org/10.1061/(ASCE)0733-9410(1985)111:6(772)
  10. Seed, H. B., Tokimatsu, K., Harder, L., and Chung, R.(1985), Influence of SPT Procedures in Soil Liquefaction Resistance Evaluations, Journal of Geotechnical Engineering, Vol. 111, No. 12, pp. 1425-1445. https://doi.org/10.1061/(ASCE)0733-9410(1985)111:12(1425)
  11. Thevanayagam, S., Mohan, S.(2000), Intergranular State Variables and Stress Strain Behavior of Silty Sands, Geotechnique, Vol. 50, No. 1, pp. 1-23. https://doi.org/10.1680/geot.2000.50.1.1
  12. Thevanayagam, S., Shenthan, T., Mohan., S., and Liang., J. (2002), Undrained Fragility of Clean Sands, Silty Sands and Sandy Silt, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 128, No. 10, pp. 849-859. https://doi.org/10.1061/(ASCE)1090-0241(2002)128:10(849)
  13. Tronsco, J. H., and Verdugo, R.(1985), Silt Content and Dynamic Behavior of Tailing sands, Proceedings. Twelth International Conference on Soil Mech. and Found. Eng., San Francisco, pp. 1311-1314.
  14. Vaid, V. P.(1994), Liquefaction of Silty Soils, Ground Failures Under Seismic Conditions, Geotechnical Special Publication No. 44, pp. 1-16.
  15. Vaid, V. P., Chern, J. C.(1985), Cyclic and Monotonic Undrained Response of Saturated Sands, Advances in the art of Testing Soils under Cyclic Conditions, ASCE Annual Convention, Detroit, pp. 120-147.
  16. Vaid, Y. P., Chung, E.K.F., and Kuerbis, R. H.(1989), Preshearing and Undrained Response of Sands, Soils and Foundations, Vol. 29, No. 4, pp. 49-61. https://doi.org/10.3208/sandf1972.29.4_49