Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Model Tests and GIMP (Generalized Interpolation Material Point Method) Simulations of Ground Cave-ins by Strength Reduction due to Saturation

불포화 강도 유실에 의한 지반함몰 현상의 모형 실험 재현 및 일반 보간 재료점법을 활용한 수치적 모사

  • Lee, Minho (Dept. of Civil and Environmental Engrg., Seoul National Univ.) ;
  • Woo, Sang Inn (Institute of Engrg. Research, Seoul National Univ.) ;
  • Chung, Choong-Ki (Dept. of Civil and Environmental Engrg., Seoul National Univ.)
  • 이민호 (서울대학교 건설환경공학과) ;
  • 우상인 (서울대학교 공학연구원) ;
  • 정충기 (서울대학교 건설환경공학과)
  • Received : 2017.11.01
  • Accepted : 2017.11.22
  • Published : 2017.12.31
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Abstract

This study presents direct shear tests, model tests, and numerical simulations to assess the effect of reduction of soil strength because of saturation during formation of ground cave-in caused by damaged sewer pipe lines. The direct shear test results show that the saturation affects the cohesion of soil significantly although it does not influence the friction angle of soil. To experimentally reproduce ground cave-in, the model tests were performed. As ground cave-ins were accompanied with extreme deformation, conventional finite element method has difficulty in simulating them. The present study relies on generalized interpolation material point method, which is one of meshless methods. Although there are differences between the model test and numerical simulation caused by boundary conditions, incomplete saturation, and exclusion of groundwater flow, similar ground deformation characteristics are observed both in the model test and numerical simulation.

본 연구에서는 하수관 손상에 의한 지반함몰 발생 과정에서 지반의 포화도 상승에 따른 흙의 불포화 강도 저하의 영향을 파악하기 위하여, 직접 전단 실험, 모형 실험, 그리고 수치해석을 수행하였다. 직접 전단 시험 결과, 흙의 마찰각은 포화도의 영향을 크게 받지 않으나, 점착력은 포화도의 영향을 크게 받음을 알 수 있다. 포화도 상승에 따른 강도저하의 영향만을 고려하기 위하여, 물의 침투효과를 배제한 모형 실험을 실시하여 지반 함몰 현상을 재현하였다. 지반 함몰은 대변위를 동반하며, 기존 유한요소법의 적용이 어렵다. 본 연구에서는 대변위 해석 기법인 일반 보간 재료점법을 사용하여 수행한 모형실험을 수치적으로 모사하였다. 비록 경계 조건 차이, 불완전 포화, 손상부 연결관의 폐색등에 의해 함몰 시간 등에는 차이가 있었지만, 유사한 토체의 변형 거동이 모형 실험과 수치해석에서 발견되었다.

Keywords

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