Journal of the Korean Geosynthetics Society (한국지반신소재학회논문집)

Korean Geosynthetics Society (한국지반신소재학회)
권호 표지
DOI QR코드

DOI QR Code

The Behavior on Stress and Settlement of GCP Composite Ground with Different Shear Strength of Soil

GCP로 개량된 복합지반의 지반강도 별 응력 및 침하거동

  • Na, Seung-Ju (Dept. of civil Engineering, College of Engineering, Chosun University) ;
  • Kim, Daehyeon (Dept. of civil Engineering, College of Engineering, Chosun University) ;
  • Kim, Gyeong-Eop (Dept. of civil Engineering, College of Engineering, Chosun University)
  • Received : 2017.06.28
  • Accepted : 2017.09.26
  • Published : 2017.09.30
Download PDF
⟨ Previous Next ⟩

Abstract

Although the Granular Compaction Pile (GCP) has been used for many decades, several failures still occur such as bulging, shear failure and other phenomena, indicating that more refined study is needed. The main objective of the study is to evaluate the stress concentration ratio for both area replacement ratio and shear strength of soil through literature review and numerical analysis. Numerical analysis using the finite element program ABAQUS has been performed for the composite ground with GCP. The behavior stress and settlement of composite ground have been analyzed for both the area replacement ratio (10~40%) and shear strength of soil (25~75 kPa). As a result of numerical analysis, as the soil strength and area replacement ratio increased, the average stree related coefficient and stress concentration ratio for depth tended to decrease, and stress related coefficient of upper layer tend to decrease equally, but the stress concentration ratio decreased. Therefore, tendency that the value in th upper layer differs from the value in other depths was displayed. Care should be taken because it is possible to make mistakes in designing the entire composite ground with the values measured in the upper layer. Also, the settlement reduction factor was compared with the existing equation and numerical analysis. And the value obatined from the existing equation and numerical analysis are similar.

쇄석다짐말뚝(GCP)은 수십 년 동안 사용되어 왔지만, 팽창, 전단파괴와 기타 현상과 같은 파괴가 여전히 발생하여 보다 정교한 연구가 필요한 실정이다. 본 연구에서는 선행연구 분석과 수치해석을 통해 치환율과 지반강도에 따른 응력 및 침하거동을 분석하고자 하였다. 이를 위해 유한요소해석 프로그램 ABAQUS를 사용하여 GCP로 개량된 복합지반을 모델링하여 지반강도와 치환율에 따라 복합지반의 응력과 침하를 분석하였다. GCP로 개량된 복합지반에 대하여 유한요소법을 이용한 수치해석을 실시하였으며, 치환율과 지반강도에 따른 복합지반의 응력관련계수와 침하저감계수의 관계를 분석하였다. 분석결과, 지반강도와 치환율이 증가할수록 깊이 별 평균 응력관련계수와 응력분담비는 증가하는 경향이 나타났다. 상부에서의 응력관련계수는 동일하게 증가하는 경향이 나타났지만, 응력분담비는 감소하였다. 따라서 상부층에서의 값은 다른 깊이에서의 값들과 다른 경향이 나타나므로 상부층에서의 측정된 값으로 복합지반 설계 시 과오를 범할 수 있으니 주의가 필요하다. 또한 기존 침하저 감계수식과 수치해석을 통한 침하저감계수와 비교 분석하였는데, 기존 식과 수치해석을 통하여 구한 값은 유사하게 나타났다.

Keywords

References

  1. A. Zahmatkesh and A. J. Choobbasti (2010), "Settlement Evaluation of Soft Clay Reinforeced by stone Columns, Considering the Effect of Soil Compaction", Department of Civil Engineering, Babol University of Technology Babol, Irna.
  2. Aboshi, H. Ichinotom E., Enoki, M. and Harada, K. (1979), "The Compozer - a Method to Improved Characteristics of Soft Clays by Inclusion of Larger Diameter Sand Column", Proc. of Int. Conf. on Soil Reinforcement, Paris, pp.211-216.
  3. Balaam, N. P. and Poulos, H. G. (1983), "The Behavior of Foundations Supported by Clay Stabilised by Stone Columns", Proceedings, 8th European Conference on Soil Mechanics and Foundation Engineering : Improvement of Ground, Helsinki, Vol.1, pp.199-204.
  4. Barksdale, R. D. (1981), "Site Improvement in Japan Using Sand Compaction Piles", Georgia Institute of Technology, Atlanta.
  5. Busan New Port Corp. (1999), Report of North Container Terminal, pp.6.50-6.59.
  6. Choi, J. W., Lee, D. Y. and Yoo, C. S. (2013), "Undrained Characteristics of Geogrid-Encased Stone Column under Cyclic Load Using Reduced-Scale Model Tests", Journal of Korean Geotechnical Society, Vol.29, No.1, pp.109-120. https://doi.org/10.7843/kgs.2013.29.1.109
  7. Chow, Y. K. (1996), "Settlement Analysis of Sand Compaction Pile", Soils and Foundation, Volume 36 - $n^{\circ}1$, Japanese Geotechnical Society, pp.111-113. https://doi.org/10.3208/sandf.36.111
  8. Chun, B. S and Yeoh, Y. H. (2001), "Composite Ground Effects on Small Area Replacement Ratio of Sand Piles", Journal of Korean Geo-Environmental Society, Vol.2, No.3, pp.57-69.
  9. Dassault Systemes. (2008), Abaqus Version 6.12 Documentation. Providence, RI: Dassault Systemes.
  10. Goughnour R. R. and Bayuk A.A (1979), "A Field Study of Long-Term Settlement of Loads Supported by Stone Columns in Soft Ground", Proceedings, International Conference on Soil Reinforcement: Reinforced Earth and Other Techniques, Vol.1 Paris: 279-286.
  11. Han, S. J., Yoo, H. K., Kim, B. I. and Kim, S. S. (2013), "Settlement Characteristics fo Soft Ground Applying the Suction Drain Method", Journal of Korean Geotechnical Society, Vol.29, No.3, pp.15-27. https://doi.org/10.7843/kgs.2013.29.3.15
  12. Kim, I. G. (2003), Finite element Analysis for the behavior Lateral Displacement due to Embank on Soft Ground, Chosun University, Master Thesis.
  13. Kim, J. H. (2009), Experimental Study on Composite Ground Behavior and Aspect of Clay Gone Through Compaction Pile of Recycled Aggregate Compaction Piles, Hongik University, Master Thesis.
  14. Kim, M. S. (2016), The Behavior of Soft Ground Reinforced with Granular Compaction Pile, Chosun University, Master Thesis.
  15. Kim, M. S., Na, S. J., Yang, Y. H. and Kim, D. H. (2016), "Analysis on the Analytical Behavior of Soft Ground Reinforced with Granular Compaction Piles", Journal of Korean Geo-Environmental Society, Vol.15, No.3, pp.27-37.
  16. Lee, C. H., Lim, H. D. and Lee, W. J. (2005), "Finite Element Analysis of GCP Ground with Replacement Ratio", KSCE Journal of Civil Engineering, Vol.2005, No.10, pp. 5459-5462.
  17. Lee, M. H. (2004), A Study on the Load Support Mechanism and Stress Distribution Characteristic of Crushed-Stone Compaction Piles, Busan University, Ph. D. Thesis.
  18. Mohamed, E. and Basuony, E. G.(2016), "Behavior of Raft Foundation Resting on Improved Soft Soil with Conventional Granular Piles, Journal of Scientific and Engineering Research, Vol.3, No.4, pp.428-434.
  19. Moon, I. J., Yoo, W. K. and Kim, B. I. (2012), "A Study on the Settlement and Bearing Capacity of the SCP, GCP Method with Low Raplacement Ratio by 1g Model Tests", Journal of Korean Geotechnical Society, Vol.2012, No.10, pp.1187-1190.
  20. Na, S. J., Kim, M. S., Park, K. H. and Kim, D. H. (2016), "Stress Concentration Ratio of GCP Depending on the Mixing Ratio of Crushed Stone and Sand", Journal of Korean Geotechnical Society, Vol.32, No.9, pp.37-50. https://doi.org/10.7843/KGS.2016.32.9.37
  21. Priebe, H.(1976), "Estimating Settlements in a Gravel column Consolidation Soil", Die Bautechnik 53, German, pp.160-162.
  22. Seong, K. H. (2003), (A) Study on the Behavior aspect of Soft Ground under a Embankment Loading, Chosun University, Master Thesis.
  23. Shin, H. Y. (2005), Analysis on the Behavior of Composite Ground Reinforced by Sand Compaction Pile with Low Area Replacement Ratio, Chungang University, Ph. D. Thesis.
  24. Song, M. G., Bae, W. S., Ahn, S. R. and Heo, Y. (2011), "Centrifugal Model Test on Stress Concentration Behaviors of Composition Ground under Flexible/Stiff Surcharge Loadings", Journal of Korean Geo-Environmental Society, Vol.12, No.6, pp.5-15.
  25. Yoo, C. S., Song, A. R., Kim, S. B. and Lee, D. Y. (2007), "Finite Element Modeling of Geogrid-Encased Stone Column in Soft Ground", Journal of Korean Geotechnical Society, Vol.23, No.10, pp.133-150.
  26. Zahmatkesh, A. and Choobbasti, A. J. (2010), "Settlement evaluation of soft clay reinforced by stone columns, considering the effect of soil compaction", International Journal of Recent Research and Applied Studies, Vol.3, No.2, pp.159-166.