Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
권호 표지
DOI QR코드

DOI QR Code

Slope Stability Analysis of Unsaturated Soil in Debris-Flow Occurrence Slopes

토석류 발생 사면의 불포화토 사면안정해석

  • 곽철수 (강원대학교 토목공학과) ;
  • 박병수 (강원도립대학 건설토목과) ;
  • 유남재 (강원대학교 토목공학과)
  • Received : 2011.12.22
  • Accepted : 2012.09.11
  • Published : 2012.09.28
Download PDF
⟨ Previous Next ⟩

Abstract

This paper is research results of slope stability analysis associated with seepage infiltration for unsaturated soil in debris-flow occurrence slopes. Site investigations were carried out in two slopes, located at Inje in Kangwon province where debris flow occurred in 2006 and at Yangpyung in Kyeunggi province where it occurred in 2010. For unsaturated soil sampled at the zone of debris-flow initiation, soil water characteristic curves with tempe pressure cells and shear strength parameters with newly designed shear strength apparatus were obtained respectively. The commertially available software SEEP/W was used to analyze seepage infiltration in unsaturated soil, based on their properties obtained from test results and the actual rainfall data at the moment of debris flow occurrence, and slope stability analysis with the program of SLOPE/W, associated with results of seepage analysis, was performed to simulate slope failure. As results of this research, seepage infiltration to unsaturated soil due to intensive rainfall was found to cause increase of ground water table as well as degree of saturation. Through this research slope stability analysis for unsaturated soil, considering the actual rainfall characteristic, might be a reasonable method of investigating characteristics of debris flow behavior, in particular, the moment of debris flow occurrence.

본 논문은 토석류 발생사면에서 불포화토의 침투해석을 연계 수행한 사면안정해석 연구결과이다. 2006년 강원도 인제군과 2010년 경기도 양평군에 위치한 2개소의 토석류 발생사면에 대하여 현장조사를 수행하고 붕괴발생부에서 채취한 시료로 tempe pressure cell을 이용한 함수특성곡선과 새로이 개발된 불포화토 직접전단시험기를 사용하여 불포화토의 전단강도 정수를 구하였다. 실험을 통해 획득한 물성과 토석류 발생 당시의 강우자료를 바탕으로 상용프로그램 SEEP/W를 사용하여 불포화토 침투 해석을 실시하고 그 결과와 연동하여 사면안정해석 프로그램 SLOPE/W를 사용하여 사면활동을 분석하였다. 본 연구 결과 집중강우에 의한 불포화토 지반에 강우침투의 영향으로 지하수위의 상승과 포화도의 증가로 사면안전율이 감소하여 사면활동이 발생한 것으로 나타났다. 이러한 연구 방법을 통하여 실제 강우특성을 고려한 불포화토의 사면안정해석을 실시하는 것이 토석류 발생사면의 거동특성 중 특히 발생시점을 확인할 수 있는 합리적인 방법이라 판단된다.

Keywords

References

  1. Fredlund, D. G. and Xing, A. (1994), "Equations for the soil-water characteristic curve", Canadian Geotechnical Journal, Vol.31, No.4, pp.521-532. https://doi.org/10.1139/t94-061
  2. Fredlund, D. G. (2005), "Unsaturated soil mechanics in engineering practice", Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol.132, No3, pp.286-321.
  3. Fredlund, D. G., Morgenstern, N. R., and Widger, R. A. (1978), "The shear strength of unsaturated soils", Can. Geothch. Journal, Vol.15, No.2, pp.261-276.
  4. Jeong, S. S., Choi, J. Y., and Lee, J. H. (2009), "Stability analysis of unsaturated weathered soil slopes considering rainfall duration", Journal of KSCE, Vol.29, No.1C, pp.1-9.
  5. Kim, J. H., Park, S. W., Jeong, S. S., and Yoo, J. H. (2002), "A study of stability analysis on unsaturated weathered slopes based on rainfall-induced wetting", Journal of KGS, Vol.18, No.2, pp.123-136.
  6. Kim, M. W. and Kim, Y. M. (2010), "Shear strength of weathered granite soil considering change of saturation", Journal of Korean Geo-Environmental Society(KGES), Vol.11, No.9, pp.5-14.
  7. Kim, S. K. and Ryu, C. H. (2000), "Shear strength of unsaturated decomposed soils", Journal of Korea Society of Civil Engineers (KSCE), Vol.20, No.2C, pp.109-118.
  8. Kwak, C. S., Yoo, K. S., Park, B. S., and Yoo, N. J. (2011), "Development of unsaturated direct shear testing apparatus", Proceedings of Korean Geotechnical Society(KGS) Fall National Conference, KGS, pp.266-274.
  9. Lee, H. K. and Lee, I. (2009), "A study of unsaturated-character of weathered granite soil in korea", Journal of KGES, Vol.10, No.3, pp.13-20.
  10. Oh, S. B., Mun, J. H., Kim, T. K., and Kim, Y. K. (2008), "A case study of rainfall-induced slope failures on the effect of unsaturated soil characteristics", Journal of KSCE, Vol.28, No.3C, pp.167-178.
  11. Park, S. W. and Shin, G. H. (2009), "Stability analysis on unsaturated gneiss weathered soil slopes considering wetting path soil-water characteristic curve", Journal of KSCE, Vol.29, No.5C, pp.191-198.
  12. Shin, G. H. and Park, S. W. (2006), "Effect of hysteresis on soilwater characteristic curve in weathered granite and gneiss soil slopes during rainfall infiltration", Journal of KGS, Vol.22, No.7, pp.55-64.
  13. Yune, C. Y. and Jun, K. J. (2010), "Seepage analysis on Ground water level changes for the site of debris-flow", Proceedings of KGES, pp.272-280.