DOI QR코드

DOI QR Code

낙동강 모래에 포함된 세립분의 소성지수에 따른 반복전단 특성

Cyclic Shear Characteristics of Nakdong River Sand Containing Fines with Varying Plasticity

  • 박성식 (경북대학교 공과대학 건축토목공학부) ;
  • 김영수 (경북대학교 공과대학 건축토목공학부) ;
  • 김성호 (경북대학교 공과대학 건축토목공학부)
  • 투고 : 2010.12.29
  • 심사 : 2011.04.07
  • 발행 : 2011.06.30

초록

지반의 액상화에 관한 연구는 대부분 깨끗한 모래를 대상으로 실시되었다. 하지만 실제 현장 지반이나 매립지는 깨끗한 모래만으로 이루어진 경우보다 실트나 점토와 같은 세립분을 포함한 상태로 존재하는 경우가 대부분이다. 이와 같은 현장 지반조건을 고려하기 위하여 사질토 지반 내에 포함된 세립분이 액상화에 미치는 영향에 대한 연구가 다수 수행되었으나, 대부분의 연구가 실트와 같은 비소성 세립분을 포함한 경우이다. 따라서 본 연구에서는 낙동강모래에 소성지수가 8, 18, 50, 377인 저소성 실트에서 고소성 점토질 세립분을 10% 함유한 공시체에 대하여 비배수 반복삼축시험을 실시하였다. 습윤 시료를 저다짐방법으로 느슨한 상태, 중간 상태, 조밀한 상태로 성형하였으며, 각각의 공시체에 세 종류의 반복전단응력을 가하였다. 세립분의 양은 동일하지만 공시체에 포함된 점토와 같은 소성 세립분의 소성지수가 높아질수록 액상화 저항강도는 전반적으로 감소하는 경향을 보였다. 한편, 공시체의 상대밀도가 느슨한 경우에는 세립분의 소성지수에 따른 액상화 저항강도 차이가 크지 않았으나, 조밀한 경우에는 세립분의 소성지수가 증가함에 따라 액상화 저항강도가 최대 40%까지 감소하였다.

Most experimental studies on soil liquefaction are related to clean sands. However, soils in the field or reclaimed grounds commonly contain some amounts of silt and clay rather than clean sand only. Many researchers investigated the effect of fine contents on liquefaction resistance and mainly used non-plastic fines such as silts. In this study, 10% of plastic fines with various plasticity index (PI) such as 8, 18, 50, and 377 were mixed with wet Nakdong River sand and then loose, medium, and dense specimens were prepared by undercompaction method. A series of undrained cyclic triaxial tests were carried out by applying three different cyclic stress ratios. As a result, the liquefaction resistance tended to decrease as a PI of fines in the specimens with equal fine content increased. On the other hand, the difference between loose specimens with low and high plasticity fines was not clearly observed in terms of liquefaction resistance. However, in the case of dense specimens, liquefaction resistance decreased up to 40% as a plasticity of fines increased.

키워드

참고문헌

  1. 김영수, 김대만(2008) 실트질 함유량에 따른 낙동강 모래의 비배수 반복전단거동 특성, 한국지반공학회논문집, 한국지반공학회, 제24권 제11호, pp. 79-89.
  2. 나윤영(2008) 낙동강 모래의 비배수 반복전단 강도에 대한 실트 함유율의 영향, 석사학위논문, 경북대학교.
  3. 신윤섭, 박인준, 최재순, 김수일(1999) 국내 발생 지진규모를 고려한 액상화저항강도 산정, 한국지반공학회논문집, 한국지반공학회, 제15권 제6호, pp. 307-317.
  4. 신지섭(2007) 실트함유율에 따른 낙동강 모래의 반복전단거동, 석사학위논문, 경북대학교.
  5. 심재욱, 박근보, 최재순, 김수일(2002) 실지진하중을 이용한 포화 그림 11. 소성지수에 따른 액상화 저항강도 곡선 사질토의 액상화 저항강도에 관한 실험적 연구, 한국지반공학회논문집, 한국지반공학회, 제18권 제4호, pp. 329-337.
  6. 이수근(2009) 세립분 함유량에 따른 새만금준설토의 액상화 특성에 관한 연구, 석사학위논문, 전북대학교.
  7. 이재진, 김수일, 정상섬(2010) 이방 구속 조건에서 실지진 하중을 이용한 포화사질토의 액상화 저항강도 특성, 한국지반공학회논문집, 한국지반공학회, 제26권 제2호, pp. 5-14.
  8. 황대진(1993) 실트를 포함하는 모래질 흙의 액상화강도에 관한 연구, 대한토목학회논문집, 대한토목학회, 제13권 제2호, pp.243-252.
  9. 황대진(1994) 세립분을 포함하는 모래질 흙의 액상화강도에 미치는 재학속도의 영향. 한국지반공학회지, 한국지반공학회, 제10권 제4호, pp. 119-131.
  10. Andrews, D. C. A. and Martin, G. R. (2000) Criteria for Liquefaction of Silty Soils. Proceedings of the 12th World Conference on Earthquake Engineering, Auckland, New Zealand.
  11. Bouferra, R. and Shahrour, I. (2004) Influence of fines on the resistance to liquefaction of a clayey sand. Ground Improvement, Vol. 8, No. 1, pp. 1-5. https://doi.org/10.1680/grim.2004.8.1.1
  12. Carraro, A. H., Prezzi, M., and Salgado, R. (2009) Shear Strength and Stiffness of Sands Containing Plastic or Nonplastic Fines. Journal of Geotechnical and Geoenvironmental Engineering, Vol. 135, No. 9, pp. 1167-1178. https://doi.org/10.1061/(ASCE)1090-0241(2009)135:9(1167)
  13. Chang, W.-J. and Hong, M.-L. (2008) Effects of Clay Content on Liquefaction Characteristics of Gap-Graded Clayey Sands. Soils and Foundations, Vol. 48, No. 1, pp. 101-114. https://doi.org/10.3208/sandf.48.101
  14. De Alba, P., Chan, C. K., and Seed, H. B. (1975) Determination of soil liquefaction characteristics by large-scale laboratory tests. Report No. EERC 75-14.
  15. Erten, D. and Maher, M. H. (1995) Cyclic undrained behavior of silty sand. Soil Dynamics and Earthquake Engineering, Vol. 14, pp. 115-123. https://doi.org/10.1016/0267-7261(94)00035-F
  16. Fei, H. C. (1991) The characteristics of liquefaction of silt soil. Soil Dynamics and Earthquake Engineering V, Computational Mechanics Publications and Elsevier Applied Science, London, pp. 293-302.
  17. Finn, W. L, Ledbetter, R. H., and Wu, G. (1994) Liquefaction in silty soils: design and analysis. Ground Failure under Seismic conditions, Geotechnical Special Publication, No. 44, pp. 51- 76.
  18. Garga, V. and Mckay, L. (1984) Cyclic triaxial strength of mines tailings. Journal of Geotechnical Engineering, Vol. 110, No. 8, pp. 1091-1105. https://doi.org/10.1061/(ASCE)0733-9410(1984)110:8(1091)
  19. Guo, T. and Prakash, S. (1999) Liquefaction of silts and silt-clay mixtures. Journal of Geotechnical and Geoenvironmental Engineering, Vol. 125, No. 8, pp. 706-710. https://doi.org/10.1061/(ASCE)1090-0241(1999)125:8(706)
  20. Howie, J. A., Shozen, T., and Vaid, Y. P. (2002) Effect of Ageing on Stiffness of Very Loose Sands. Canadian Geotechnical Journal, Vol. 39, No. 1, pp. 149-156. https://doi.org/10.1139/t01-085
  21. Ishihara, K., Troncoso, J., Kawase, Y., and Takahashi, Y. (1980) Cyclic strength characteristics of tailings materials. Soils and Foundations, Vol. 20, No. 4, pp. 127-142. https://doi.org/10.3208/sandf1972.20.4_127
  22. Kishida, H. (1969) Characteristics of liquefied sands during Mino- Owari, Tohnankai, and Fukui Earthquakes. Soils and Foundations, Vol. 9, No. 1, pp. 75-92. https://doi.org/10.3208/sandf1960.9.75
  23. Koester, J. P. (1994) The influence of fine type and content on cyclic strength. Ground Failure under Seismic conditions, Geotechnical Special Publication, No. 44, pp. 17-33.
  24. Ladd, R. S. (1978) Preparing test specimens using undercompaction. Geotechnical Testing Journal, Vol. 1, No. 1, pp. 16-23. https://doi.org/10.1520/GTJ10364J
  25. Law, K. T. and Ling, Y. H. (1992) Liquefaction of granular soils with non-cohesive and cohesive fines. Proceedings of the 10th World Conference on Earthquake Engineering, Rotterdam, pp. 1491-1496.
  26. Lee, K. L. and Albaisa, A. (1974) Earthquake induced settlements in saturated sands. Journal of the Geotechnical Engineering Division, Vol. 100, No. GT4, pp. 387-406.
  27. Miura, S., Kawamura, S., and Yagi, K. (1995) Liquefaction damage of sandy and volcanic grounds in the 1993 Hokkaido Nansel-Oki Earthquake. Proceedings of the 3rd International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, St. Louis, Missouri, Vol. 1, pp. 193-196.
  28. Orense, R. P., Morimoto, I., Yamamoto, Y., Yumiyama, T., Yamamoto, H., and Sugawara, K. (2003) Study on wall-type gravel drains as liquefaction countermeasure for underground structures. Soil Dynamics and Earthquake Engineering, Vol. 23, pp. 19-39. https://doi.org/10.1016/S0267-7261(02)00152-5
  29. Polito, C. P. (1999) The effects of non-plastic and plastic fines on the liquefaction of sandy soils. Ph.D. thesis, Virginia Polytechnic Institute and State University.
  30. Puri, V. K., Das, B. M., and Prakash, S. (1996) Liquefaction of sility soils. International Journal of Offshore and Polar Engineering, Vol. 6, No. 4, pp. 308-312.
  31. Seed, H. B. and Idriss, I. M. (1982) Ground motion and soil liquefaction during earthquakes. Monograph, Earthquake Engineering Research Institute, Oakland, Ca.
  32. Seed, H. B., Idriss, I. M., and Arango, I. (1983) Evaluation of liquefaction potential using field performance data. Journal of Geotechnical Engineering Division, Vol. 109, No. 3, pp. 458- 482. https://doi.org/10.1061/(ASCE)0733-9410(1983)109:3(458)
  33. Seed, H. B., Martin, P. P., and Lysmer, J. (1976) Pore-water pressure changes during soil liquefaction. Journal of the Geotechnical Engineering Division, Vol. 102, No. GT4, pp. 323-346.
  34. Seed, H. B., Tokimatsu, K., Harder, L. F., and Chung, R. M. (1985) The 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)
  35. Tohno, I. and Yasuda, S. (1981) Liquefaction of the ground during the 1978 Miyagiken-Oki earthquake. Soils and Foundations, Vol. 21, No. 3, pp. 18-34. https://doi.org/10.3208/sandf1972.21.3_18
  36. Tronsco, J. H. and Verdugo, R. (1985) Silt content and dynamic behavior of tailing sands. Proceedings of the 12th International conference on Soil Mechanics and Foundation Engineering, San Francisco, pp. 1311-1314.
  37. Vaid, Y. P. (1994) Liquefaction of silty soils. Ground Failure under Seismic conditions. Geotechnical Special Publication, No. 44, pp. 1-16.
  38. Wang, W. (1979) Some Findings in Soil Liquefaction. Research Report, Water Conservancy and Hydroelectric Power Scientific Research Institute, Beijing, China, pp. 1-17.
  39. Zlatovic, S. and Ishihara, K. (1997) Normalized behavior of very loose non-plastic soils: effects of fabric. Soils and Foundations, Vol. 37, No. 4, pp. 47-56. https://doi.org/10.3208/sandf.37.4_47