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A Geophysical Survey of Subsidence area around Limestone Mine Sites

석회석 광산지역 지반침하 분석을 위한 물리탐사 기술 적용 연구

  • Hong, Jinpyo (Department of Energy and Resources Engineering, Kangwon National University) ;
  • Ji, Yoonsoo (Department of Energy and Resources Engineering, Kangwon National University) ;
  • Oh, Seokhoon (Department of Energy and Resources Engineering, Kangwon National University) ;
  • Choi, Sungoong (Department of Energy and Resources Engineering, Kangwon National University)
  • Received : 2015.10.08
  • Accepted : 2015.11.25
  • Published : 2015.11.30

Abstract

Electrical resistivity surveys were conducted at two subsidence areas near and at limestone mine sites, respectively, in order to estimate their causes of subsidence and the regions of potential occurrence. In addition, the linkages of mine development with these subsidences were investigated by the rock engineering analysis. Two study areas have different geological setting. One study site is the land subsidence area, which contains clay and sandy soil near the limestone mine, The other study site is the land subsidence area located just above the mine, which is expected to be relevant to the limestone mine. As results of two-dimensional (2D) electrical resistivity surveys at the sites 1 and 2, low resistivity zones, which are 70 ~ 120 ohm-m and 20 ~ 50 ohm-m, respectively, were found under the subsidence zones. For the study site 1, the possibility of subsidence was confirmed by using three-dimensional (3D) inversion performed with 2D resistivity profiles. For the study site 2, the cause of the subsidence and the possibility of subsidence occurrence were confirmed by rock engineering computation with regard to measurement line 7 in which low resistivity accompanied by subsidence area was observed.

지반침하가 발생한 두 곳의 석회석 광산 지역에서 전기비저항 탐사를 수행하여 침하 원인과 향후 위험지역을 추정하고자 하였으며, 해석의 한계성을 극복하기 위해 암반공학적 해석을 수행하여 광산 개발과의 연계성을 검토하고자 하였다. 연구지역은 점토와 모래질 토층의 석회석 광산 인근 지대(연구지역 1)와 석회석 광산과의 연관성이 예측되는 채굴적 상부 지대(연구지역 2)를 대상으로 하였다. 연구지역 1, 2의 2차원 전기비저항 탐사 결과, 침하 발생 위치 하부에서 각각 70 ~ 120 ohm-m, 20 ~ 50 ohm-m의 상대적으로 저비저항 이상대가 확인되었다. 연구지역 1은 2차원 전기비저항 단면을 파악하여 3차원 역산 해석을 통해 지반침하의 가능성을 확인하였다. 연구지역 2는 침하가 발생하고 이상대가 관찰된 측선 7번에 대하여 암반공학적 안정성 해석을 실시하고, 침하의 원인과 향후 침하 발생 가능성을 확인하였다.

Keywords

References

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