The Journal of Engineering Geology (지질공학)

The Korean Society of Engineering Geology (대한지질공학회)
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Field Investigation and Stability Analysis of a Volcanic Rock Slope at the Song-Gok site, Wan-Do

완도 송곡지구 화산암류 비탈면의 현장조사 및 안정성 검토 사례 연구

  • Kim, Hong-Gyun (Geotechnical Engineering Research Division, Korea Institute of Construction Technology) ;
  • Ok, Young-Seok (Geotechnical Engineering Research Division, Korea Institute of Construction Technology) ;
  • Kim, Seung-Hyun (Geotechnical Engineering Research Division, Korea Institute of Construction Technology) ;
  • Koo, Ho-Bon (Geotechnical Engineering Research Division, Korea Institute of Construction Technology)
  • 김홍균 (한국건설기술연구원 Geo-인프라연구실) ;
  • 옥영석 (한국건설기술연구원 Geo-인프라연구실) ;
  • 김승현 (한국건설기술연구원 Geo-인프라연구실) ;
  • 구호본 (한국건설기술연구원 Geo-인프라연구실)
  • Received : 2013.05.13
  • Accepted : 2013.06.24
  • Published : 2013.06.30
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Abstract

Volcanic activity commonly creates a highly complicated volcanic complex due to the admixture of lava flow and sedimentation of volcanic ash. The Song-Gok site is composed of volcanic rocks that collapsed at the lower part of the slope, in combination with several discontinuities in and around a fault. The results of projection analysis indicated the possibility of plane, wedge, and toppling failure in the failure section. The results of discontinuity modeling using the Distinct Element Method (DEM) revealed a total displacement of 207 mm and a joint shear displacement of 114 mm. The yield surface zone was verified at the fault plane of the failure section. In geotechnical terms, volcanic rock slopes are characteristically vulnerable to failure because of differential weathering among the various rock types, the effect of groundwater based on the permeability of the rocks, and the presence of systematic joints generated by the cooling and contraction of lava. When considering the stability of a volcanic rock slope, it is necessary to consider data such as the geological features of the rock, as obtained through detailed geological survey, and variations in discontinuities and rock blocks.

화산활동은 용암의 분출과 화산재의 퇴적 작용이 복합적으로 발생함에 따라 지질학적으로 매우 복잡한 화산암복합체를 형성하는 경우가 많다. 화산암류 암석들로 구성된 송곡 지구는 단층을 중심으로 한 여러 불연속면의 조합으로 비탈면 하단부에서 붕괴가 발생하였다. 붕괴부를 중심으로 한 평사투영 해석 결과 모든 형태의 붕괴 가능성이 인지되었으며, 개별요소법(DEM)을 이용한 불연속면 거동 특성 분석 결과, 전체변위 207 mm, 절리 최대전단 변위 114 mm로 나타났으며, 소성 영역 발생 구간은 붕괴부의 단층면에서 확인되었다. 화산암류 비탈면은 암종간의 차별 풍화, 암석의 높은 투수성에 기인한 지하수 영향, 냉각 수축에 의한 체계적 절리 발달로 인해 공학적으로 취약한 특성을 보인다. 화산암류 비탈면의 안정화 대책 고려시, 상세 지질조사를 통한 구성암석의 지질학적 특성, 불연속면과 이완암블록의 변화량 분포 등의 자료가 활용되어야 할 것이다.

Keywords

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