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

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

DOI QR Code

Characteristics of Shear Strength and Consolidation Behavior of Soft Ground according to Stage Fill

단계성토에 따른 연약지반의 전단강도 및 압밀거동 특성

  • Bang, Seongtaek (Department of Construction & Disaster Prevention Engineering, Kyungpook National University)
  • Received : 2020.05.20
  • Accepted : 2020.06.26
  • Published : 2020.07.01
Download PDF
⟨ Previous Next ⟩

Abstract

The soft ground in the southwest coastal area composed of marine clay is greatly influenced by sediment composition, particle size distribution, particle shape, adsorption ions and pore water characteristics, tide and temperature. In addition, the geotechnical properties are very complex due to stress history, change in pore water, dissolution process and gas formation. In this study, the physical and mechanical properties of the soft ground were evaluated through field tests and laboratory tests to investigate the strength increase characteristics according to consolidation on the soft ground in the southwest coast. In addition, in order to understand the consolidation behavior of soft ground such as subsidence, pore water pressure, horizontal displacement of soil by embankment load, measuring instruments such as pore water pressuremeter, settlement gauge, inclinometer and differential settlement gauge was installed, and a piezocon penetration test was carried out step by step to confirm the increase in shear strength of the ground. Through this, it was confirmed that the shear strength of the ground is increased according to the stages of filling. In addition, by evaluating the properties of consolidation behavior, strength increase and consolidation prediction by empirical methods and theories were compared to analyze the characteristics of strength increase rate and consolidation behavior in consideration of regional characteristics.

해성점토로 구성된 서남해안 지역의 연약지반은 퇴적물의 성분, 입자크기의 분포, 입자형상, 흡착이온 및 간극수의 특성, 조류, 온도 등에 의해 많은 영향을 받는다. 또한, 응력이력, 간극수의 변화, 용탈과정, 가스형성 등의 지반공학적 특성은 매우 복잡한 양상을 나타내고 있다. 본 연구에서는 서남해안 연약지반을 대상으로 압밀에 따른 강도증가 특성을 규명하기 위하여 현장시험 및 실내시험을 통하여 연약지반의 물리적·역학적 특성을 평가하고 성토하중에 의한 지반의 침하, 간극수압, 수평변위 등 연약지반의 압밀거동을 파악하기 위하여 간극수압계, 침하계, 경사계, 층별침하계 등의 계측기를 설치하고, 지반의 전단강도증가를 확인하기 위해 단계별로 피에조콘 관입시험을 실시하였다. 이와 같은 실험을 통하여 단계별 성토에 따른 지반의 전단강도증가를 확인하고 압밀침하량을 측정하여 기존에 제시된 경험적 방법 및 이론에 의한 강도증가와 압밀측정치를 비교하여 강도증가율 및 압밀거동을 분석하였다.

Keywords

References

  1. Hansbo, S. (1957), A new approach to the determination of the shear strength of clay by the fall-cone test, Proc. Swedish Geotechnical Institute, No. 14, pp. 42-46.
  2. Hong, W. P., Song, Y. S. and Lee, G. H. (2000), Increment of shearing strength of soft clay in Kwangyang, Institute of Technology and Science, Chungang University, pp. 1-12 (In Korean).
  3. Jeong, S. G. (2015), Mechanical characteristics of dredged and reclaimed ground with low plasticity from western coastal site, Journal of Korean Geosynthetics Society, Vol. 14, No. 4, pp. 97-104 (In Korean). https://doi.org/10.12814/jkgss.2015.14.4.097
  4. Jun, S. H., Yoo, N. J. and Park, B. S. (2008), Evaluation of constitutive relationships and consolidation coefficients for prediction of consolidation characteristics of dredged and reclaimed ground, Journal of the Korean Geo-Enviromental Society, Vol. 9, No. 6, pp. 31-41 (In Korean).
  5. Kim, J. K., Kim, Y. U., Choi, I. G. and Park, Y. M. (2001), Estimation of geotechnical characteristics of the marine clay at Incheon international airport marine clay using piezocone and dilatometer tests, Journal of The Korean Geotechnical Society, Vol. 17, No. 2, pp. 41-49 (In Korean).
  6. Kim, S. K. (1975), Engineering characteristics of marine clays in Korea, Proc. of 15th Asian Regional Conference on SMFE, Vol. 1, pp. 35-43.
  7. Kim, S. K., Yea, G. G., Kim, K. S. and Kim, H. Y. (2011), Consideration of physical and compression characteristics among western and southern coastal marine clays, Journal of the Korean Geo-Enviromental Society, Vol. 12, No. 6, pp. 43-51 (In Korean).
  8. Kim, Y. H., Jang, J. H., Choi, D. C. and Chun, B. S. (2009), Evaluation of piezocone factors for soft ground in the region of Nakdong river estuary using statistical analysis, Journal of the Korean Geo-Enviromental Society, Vol. 10, No. 7, pp. 53-66 (In Korean).
  9. Lee, S. H., Jung, J. S., Ji Y. H. and Kim, S. M. (2012), A study on the long-term settlements characterlistics and settlement prediction of soft ground in west-south region, Journal of the Korean Geo-Enviromental Society, Vol. 13, No. 4, pp. 77-91 (In Korean).
  10. Lee, S. J. (1997), Estimations of Geotechnical Properties from Piezocone Penetration Tests in South Korea, Ph.D. Dissertation, University of Seoul, pp. 42-95 (In Korean).
  11. Lunne, T., Eide, O. and De Ruiter, J. (1976), Correlation between cone resistance and vane shear strength in some scandinavian soft to medium stiff clays, Canadian Geotechnical Journal, Vol. 13, No. 4, pp. 430-431. https://doi.org/10.1139/t76-043
  12. Park, S. Y., Kim, K. B., Lee, Y. K. and Baek, S. C. (2012), Evaluation of piezocone coefficient of soft grounds in the areas of Gyeonggi and Incheon, Journal of the Korean Geo-Enviromental Society, Vol. 13, No. 5, pp. 41-49 (In Korean).
  13. Schmertmann, J. H. (1955), The undisturbed consolidation behavior of clay, Journal of ASCE, Vol. 120, pp. 1201-1233.
  14. Skempton, A. W. (1986), Standard penetration test procedures and the effects in sands of overburden pressure. Relative density, particle size, ageing and overconsolidation, Geotechnique, Vol. 36, No. 3, pp. 425-427. https://doi.org/10.1680/geot.1986.36.3.425
  15. Song, M. S. (1988), Relationship of soil parameters of marine clay in the South Korea, Master's Dissertation, University of Hanyang, pp. 20-35 (In Korean).
  16. Yoon, K. 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 (In Korean).