Journal of the Korean Society of Hazard Mitigation (한국방재학회 논문집)

Korean Society of Hazard Mitigation (한국방재학회)
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Infiltration and Stability Analysis of Weathered Granite Slope considering Rainfall Patterns

강우패턴을 고려한 화강풍화토 사면의 침투 및 안정성 분석

  • Lee, Ji Sung (Department of Ocean Engineering, Pukyong National Univ.) ;
  • Kim, Yun Tae (Department of Ocean Engineering, Pukyong National Univ.)
  • 이지성 (국립부경대학교 해양공학과) ;
  • 김윤태 (국립부경대학교 해양공학과)
  • Received : 2013.07.31
  • Accepted : 2013.10.10
  • Published : 2013.10.31
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Abstract

Many slope disasters occur in many parts of the world during rainy season. Rainfall is one of the significant factors related to the landslides which cause a considerable damage to society. The rainfall-induced landslides in unsaturated slopes generally have shallow failure and are triggered by decrease in matric suction during rainfall. In this paper, effects of rainfall patterns on slope stability of the unsaturated weathered soil were investigated. Landslides inventory consisted of 106 landslides data from 1999 to 2011 was used to induce two rainfall patterns: strong major rainfall(SMR) pattern and strong antecedent rainfall(SAR) pattern. SMR pattern is a rainfall type in which the major rainfall of the landslide event day provides a key role on the landslide occurrence. SAR pattern is that the antecedent rainfall of the 1-antecedent day gives an important role on the landslide occurrence. Constant rainfall pattern was also used for comparison in numerical analysis. Combined seepage and stability analyses were performed to study the stability of slope subjected to various rainfall patterns. The results of numerical analysis indicated that variation of factor of safety of weathered granite slope depended on rainfall pattern, rainfall intensity and soil permeability.

전 세계에서 우기 시 내린 유발강우로 인해 사면파괴가 발생하고, 이러한 사면파괴로 재산 및 인명에 상당한 피해를 주고 있다. 강우로 인한 사면파괴는 불포화 지반에서 모관흡수력의 감소로 인해 얕은 파괴형태로 발생한다. 본 연구에서는 실제 사면파괴 당시의 강우패턴을 산정하여 강우패턴이 화강풍화토 사면의 안정성에 미치는 영향을 분석하고자 하였다. 1999부터 2011년까지 사면파괴가 발생한 화강풍화토 지반을 대상으로 붕괴 유발 강우량을 분석하였다. 취합된 사면붕괴 사례는 총 106개이다. 국내 화강풍화토 사면에서 유발된 사면파괴와 유발강우에 대한 분석을 통해 2개의 사면파괴 유발 강우패턴을 도출하였다: 당일 강우량이 사면파괴에 큰 영향을 미치는 Strong major rainfall(SMR) 패턴과 파괴 하루 전 선행강우가 사면안정성에 영향을 미치는 Strong antecedent rainfall(SAR) 패턴. 또한 비교분석을 위하여 일정강우(Constant rainfall, CR) 패턴을 산정하여 불포화 사면의 침투 및 안정해석을 수행하였다. 해석결과, 사면의 안전율은 강우패턴, 강우강도 및 투수계수에 의존하는 것을 알 수 있다.

Keywords

Acknowledgement

Supported by : 한국연구재단

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