Journal of the Mineralogical Society of Korea (한국광물학회지)

The Mineralogical Society of Korea (한국광물학회)
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A Study on Mineralogical and Basic Mechanical Properties of Fault Gouges in 16 Faults, Korea

국내 16개 단층대 단층비지의 광물학적 및 기초물성에 관한 연구

  • Moon, Seong-Woo (Department of Earth and Environmental Sciences, Chungbuk National University) ;
  • Yun, Hyun-Seok (Department of Earth and Environmental Sciences, Chungbuk National University) ;
  • Choo, Chang Oh (Department of Geology) ;
  • Kim, Woo-Seok (Geotechnical Engineering Research Division) ;
  • Seo, Yong-Seok (Department of Earth and Environmental Sciences, Chungbuk National University)
  • 문성우 (충북대학교 지구환경과학과) ;
  • 윤현석 (충북대학교 지구환경과학과) ;
  • 추창오 (경북대학교 지질학과) ;
  • 김우석 (한국건설기술연구원 지반연구소) ;
  • 서용석 (충북대학교 지구환경과학과)
  • Received : 2015.06.04
  • Accepted : 2015.06.26
  • Published : 2015.06.30
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Abstract

Because fault gouge developed at the center of fault is recognized as one of the most important weak sites, it is evident that clay mineralogy and physical properties greatly affect the rock stability. The purpose of this study is to establish the relationship of mineralogy and physical factors that control rock stability in fault zones. We analyzed a total of 51 samples from 16 main faults which were selected from a Korea fracture map, using XRD, SEM, and physical analyses like unit weight, friction and cohesion properties. Though it is considered that the most common clay minerals comprising fault gouge are kaolinite, illite and smectite, clay mineralogy slightly varies depending on lithology: illite > smectite > kaolinite and chlorite in volcanic rocks, kaolinite and chlorite > illite > smectite in sedimentary rocks, and illite > smectite > kaolinite and chlorite in abundance, respectively. Friction angle decreases with increasing clay content. Cohesion increases with increasing clay content below the 45 % region while it decreases with increasing clay content at the region higher than 45%, with some scatters in the data. It is likely that these results are ascribed to the physical heterogeneity of fault gouges with varying content of different clay minerals.

단층비지는 단층의 중심부에 분포하면서 연약대를 형성하므로 단층비지의 광물학적 특성과 물성은 암반의 안정성에 크게 영향을 미친다. 본 연구에서는 단열구조도를 참고하여 중, 대규모의 주요 단층을 선정하였으며, 총 16지역의 단층 코어부분에서 51종류의 시료를 채취하였다. XRD, SEM을 이용한 광물학적 분석과 단위중량, 마찰각, 점착력을 측정하였다. 점토광물은 대표적으로 카올리나이트, 일라이트, 스멕타이트로 나눠질 수 있으며, 화산암에는 일라이트 > 스멕타이트 > 카올리나이트와 녹니석의 순으로 함유된다. 퇴적암에는 카올리나이트와 녹니석 > 일라이트 > 스멕타이트의 순으로 풍부하다. 화강암에는 일라이트 > 스멕타이트 > 카올리나이트와 녹니석 순으로 함유된다. 마찰각은 점토함량이 높을수록 감소하며, 점착력은 분산이 심하게 나타났다. 점토광물의 함량이 45% 이하에서는 점토광물의 함량이 증가할수록 점착력이 높아지나 45% 이상에서는 점착력이 낮아지는 추세를 보인다. 이는 단층비지가 불균질하며, 점토광물의 종류와 함량에서도 넓은 범위를 가지기 때문인 것으로 보인다.

Keywords

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