Journal of the Korean Geosynthetics Society (한국지반신소재학회논문집)

Korean Geosynthetics Society (한국지반신소재학회)
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A Fundamental Study on Evaluation of Corrected Compression Index by Plasticity Index in Marine Clayey Soils

해성 점성토의 소성지수에 따른 보정압축지수 평가에 관한 기초연구

  • Received : 2018.07.31
  • Accepted : 2018.09.15
  • Published : 2018.09.30
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Abstract

The soil parameters important for the design of the soft ground are the compression index ($C_c$), the consolidation settlement and consolidation speed at the field. Compression index is obtained by laboratory consolidation test. In the laboratory consolidation test, sample disturbance always occurs. In order to correct the disturbance phenomena, the method of calculating the compression index proposed by Schmertmann (1955) is generally used. However, recent developments in sampling technology and Korean soil conditions are different from those proposed by Schmertmann. So it needs to be verified. In this study, each consolidation curve's cross void ratio is evaluated by doing consolidation test varying disturbance on high-plastic clay (CH), low-plastic clay (CL) and low-plastic silt (ML). The test results were $0.521e_0$ for low-plastic silt, $0.404e_0$ for low-plastic clay, and $0.458e_0$ for the high-plastic clay. This results were different from those of Schmertmann's suggested value of $0.42e_0$. Therefor we proposed a correction formula using the plastic index according to soil type. However, since the results of this study are limited test results, further studies on various korean soil are needed to suggest the compression index correction method according to the degree of plasticity index of soil.

연약지반 설계에 중요한 지반정수는 압축지수($C_c$)이며, 현장의 압밀침하량 및 압밀침하속도를 산출하는데 필요하다. 이러한 압축지수 산정은 실내압밀시험을 통해 얻어지는데, 실내압밀시험에서는 반드시 시료교란이 발생하며, 이러한 교란현상을 보정하기 위하여 Schmertmann(1955)이 제시한 보정 압축지수 산정방법이 일반적으로 사용되고 있다. 그러나 최근 시료 샘플링기술의 발전과 국내 지반조건 등이 Schmertmann이 제시한 것과 상이하므로 이에 대한 검증이 필요하다. 이에 본 연구에서는 저소성 실트(ML), 저소성(CL) 및 고소성 점토시료(CH)에 대하여 교란도를 변화시켜 압밀시험을 실시하여 각각의 압밀곡선의 교차 간극비를 평가하였다. 시험결과 저소성 실트(ML)의 경우 $0.521e_0$, 저소성 점토(CL)의 경우 $0.404e_0$, 고소성 점토(CH)의 경우 $0.458e_0$로 산정되어, Schmertmann이 제시한 $0.42e_0$의 보정값과 다른 결과를 확인하였으며, 흙의 종류에 따른 소성지수(PI)를 활용한 보정식을 제안하였다. 그러나 본 연구결과는 한정된 지역에서의 시험결과이므로 흙의 소성도에 따른 압축지수 보정방법을 제시하기 위해서 다양한 국내 점토에 대한 후속연구가 필요할 것으로 판단된다.

Keywords

References

  1. Al-Khafaji, A. W. N., and Andersland, O. B. (1992), "Equations for compression index approximation", Journal of Geotechnical Engineering, Vol.118, No.1, pp.148-153. https://doi.org/10.1061/(ASCE)0733-9410(1992)118:1(148)
  2. Azzouz, A. S., R. J. Krizek, and R. B. Corotis (1976), "Regression Analysis of Soil Compressibility", Soil and Foundations, Tokyo, Vol.16 No.2 pp.19-29.
  3. Bea, W. S. and Kim, J. W, (2009), "Correlations Between the Physical Properties and Compression Index of KwangYang Clay", Korean Geo-Environmental Society, Vol.10, No.7, pp.7-14.
  4. Cozzolino, V. M. (1961), "Statistical forecasting of compression index", Proc., 5th Int. Conf. on Soil Mech. and Found Engrg., Paris, France, Vol.1, pp.51-53.
  5. Jang, J. W., Choi, S. M. and Park, C. S. (2001), "A Study on the Relationship between the Physical Properties of Soil and the Compression Index of Soft Clay in Gyungnam Coastal Region", Korean Society of Coastal and Ocean Engineers, Vol.13, No.4, pp.282-289.
  6. Jeong, N. H. (1985), "A Study on the Compression Index of Remolded Clay", Master Thesis, Dan-Kuk University.
  7. Jeong, S. G. (2017), "Applicability of Preconsolidation Pressure Interpretations of Korean Marine Clays", Journal of Korean Geosynthetics Society, Vol.16, No.4, pp.93-101. https://doi.org/10.12814/JKGSS.2017.16.4.093
  8. Kang, S. H. (2003), "A study on the disturbance effect for a void-pressure relation of clay", Master Thesis, Chung Woon University, pp.32-54.
  9. Kim, D. H., Kim, K. W., and Piak, Y. S. (2003), "Relationship Between Physical Properties and Compression Index for Marine Clay", Journal of the Korean Geotechnical Society, Vol.19, No.6, pp.371-378.
  10. Koppula, S. D. (1981), "Statistical estimation of compression index". Geotechnical Testing Journal, Vol.4, No.2, pp.68-73. https://doi.org/10.1520/GTJ10768J
  11. KS F 2316 (2002), "Test method for one-dimensional consolidation properties of soils using incremental loading", KSA (Korean Standards Association).
  12. Mayne, P.W. (1980), "Cam-clay predictions of undrained strength", Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 106(11), pp.1219-1242.
  13. Nacci, V. A., Wang, M. C., and Demars, K. R. (1975), "Engineering behavior of calcareous soils", In Proceedings of Civil Engineering in the Oceans III, ASCE Specialty Conference, Newark, Del pp.9-12.
  14. Nakase, A., Kamei, T. and Kusakabe, O. (1988), "Constitutive parameters estimated by plasticity index", Journal of Geotechnical Engineering, Vol.114, No.7, pp.844-858. https://doi.org/10.1061/(ASCE)0733-9410(1988)114:7(844)
  15. Nishida, Y. (1956), "A brief note on compression index of soil", Journal of the Soil Mechanics and Foundations Division, Vol.82, No.3, pp.1-14.
  16. Park, S. B. (2016), "Evaluation of the Corrected Compression Index Considering Disturbance Effect Focusing on Plasticity Index", Master Thesis, Daejin University, pp.38-45.
  17. Rendon-Herrero, O. (1983), "Closure: universal compression index equation", Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 109(5), pp.755-761. https://doi.org/10.1061/(ASCE)0733-9410(1983)109:5(755)
  18. Schmertmann, J. H. (1955), "The undisturbed consolidation behavior of clay", Journal of ASCE, Vol.120, pp.1201-1233.
  19. Song, M. S. (1988), "A Study on the Relationship of Soil Parameter of Marin Clay in Korea", Master Thesis, Han-Yang University.
  20. Terzaghi, K. and Peck, R. (1967) "Soil Mechanics In Engineering Practice", John Wiley & Sons Inc. New York, pp.63-81.
  21. Yoon, G. L. and Kim, B. T. (2003), "Formula of Compression Index Prediction for Marine Clay in Korea", Journal of The Korean Society of Civil Engineers, Vol.23, No.3C, pp.169-176.