한국지반공학회논문집 (Journal of the Korean Geotechnical Society)

한국지반공학회 (Korean Geotechnical Society)
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선행강우와 현장 모관흡수력을 고려한 산사태 해석 방법 제안

Proposal of Design Method for Landslides Considering Antecedent Rainfall and In-situ Matric Suction

  • 김정환 (연세대학교 토목환경공학과) ;
  • 정상섬 (연세대학교 토목환경공학과) ;
  • 김용민 (연세대학교 토목환경공학과) ;
  • 이광우 (연세대학교 토목환경공학과)
  • 투고 : 2013.05.15
  • 심사 : 2013.12.12
  • 발행 : 2013.12.31
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초록

본 연구에서는 전형적인 산사태 발생 메커니즘인 강우침투현상과 현장 모관흡수력을 고려한 산사태 해석 방법을 제시하였으며, 실제 산사태가 발생된 지역을 선정하여 그 적용성을 검토하였다. 이를 위해 대상지역의 시료를 채취하여 함수특성곡선(SWCC) 실험을 수행하였으며, 불포화 투수계수를 산정하였다. 또한 초기 모관흡수력과 강우발생에 따른 모관흡수력 변화를 관측하기 위해 현장계측을 수행하였으며, 그 결과를 산사태 해석에 적용하였다. 그리고 국내 강우특성을 고려한 비탈면 설계를 위하여, 강우패턴에 따른 습윤대 깊이와 안전율 변화를 분석하였다. 특히, 선행강우 효과를 고려한 매개변수 해석을 수행하여 비탈면 안정성에 어떠한 영향을 주는지 습윤대 깊이 변화를 통해 분석하였다. 그 결과, 본 연구에서 제안한 산사태 해석 방법은 지반의 불포화 특성과 선행강우 효과를 고려할 수 있으며, 산사태 발생 위치를 적절히 예측하는 것으로 나타났다. 그리고 강우발생 시, 강우량이 후반부에 집중된 강우패턴에서 비탈면의 안전율이 가장 낮게 나타났다. 또한, 선행강우는 비탈면의 모관흡수력을 감소시켜 불안정성을 증가시키고, 이후 발생된 강우로 인해 습윤대가 깊어지면서 비탈면 파괴 위험이 증가한다.

This study presents a design method for typical rainfall-induced landslide considering in-situ matric suction. Actual landslide data are used to validate the proposed method. The soil-water characteristic curve (SWCC) and unsaturated permeability are experimentally determined to estimate hydraulic properties of testing site. The field measurement of matric suction is carried out to monitor in-situ matric suction in a natural slope subjected to rainfall infiltration, which is incorporated in the landslide analysis. The wetting band depth and safety factor of the slope are assessed to clarify the effect of domestic rainfall pattern. Especially, the effect of antecedent rainfall on the slope stability is investigated and discussed in terms of wetting band depth using parametric study. It is found from the result of this study that proposed design method can consider the characteristic of unsaturated soil and effect of antecedent rainfall. The location of the scarp zone is fairly well predicted by proposed design method. Moreover, heavy rainfall, concentrated in the backward part with time, causes the lowest safety factor of the slope. These results demonstrate that decrease in matric suction due to antecedent rainfall may trigger slope instability. After the antecedent rainfall, additional rainfall may cause the slope failure due to increasing wetting band depth.

키워드

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  2. Rainfall intensity-duration thresholds for landslide prediction in South Korea by considering the effects of antecedent rainfall pp.1612-5118, 2017, https://doi.org/10.1007/s10346-017-0892-x
  3. 강우침투에 의한 비탈면 안정해의 수리-역학적 모델을 이용한 커플링 효과 vol.31, pp.9, 2015, https://doi.org/10.7843/kgs.2015.31.9.5
  4. 불포화토 사면 안정해석에서 선행강우의 영향에 관한 연구 vol.35, pp.5, 2015, https://doi.org/10.12652/ksce.2015.35.5.1073
  5. 선행강우를 고려한 산사태 유발 강우기준(ID curve) 분석 vol.32, pp.4, 2013, https://doi.org/10.7843/kgs.2016.32.4.15
  6. 광역적 산사태 모니터링을 위한 무선센서네트워크 기술의 적용 vol.34, pp.9, 2013, https://doi.org/10.7843/kgs.2018.34.9.19
  7. Characteristics of Strength and Water Content of Mountain Ground Based on Rainfall Conditions vol.19, pp.4, 2019, https://doi.org/10.9798/kosham.2019.19.4.115
  8. 수치해석에 의한 강우 침투 시 사면 파괴시간의 확률론적 해석 vol.35, pp.12, 2013, https://doi.org/10.7843/kgs.2019.35.12.45
  9. EICP 방법으로 처리된 사질토의 전단 강성도 및 강도 증가 분석 vol.36, pp.1, 2013, https://doi.org/10.7843/kgs.2020.36.1.17