Tunnel and Underground Space (터널과지하공간)

Korean Society for Rock Mechanics and Rock Engineering (한국암반공학회)
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Comparison of Tensile Strengths in Granite Using Brazilian Tests and Hollow Cylinder Tests for Hydraulic Fracturing Test Interpretation

수압파쇄시험 해석을 위한 중공원통 인장시험과 압열인장시험 화강암 인장강도 비교

  • 조영욱 (충남대학교 대학원 지질학과 응용 지질학전공) ;
  • 장찬동 (충남대학교 자연과학대학 지질환경과학과) ;
  • 이태종 (한국지질자원연구원 지구환경연구본부 지질자원연구팀) ;
  • 김광염 (한국건설기술연구원 SOC성능연구소 Geo인프라연구실)
  • Received : 2013.07.18
  • Accepted : 2013.09.03
  • Published : 2013.10.31
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Abstract

We conducted hollow cylinder tensile strength tests and Brazilian tests in Seokmo granite to measure tensile strength necessary for estimating the magnitude of the maximum horizontal principal stress in hydraulic fracturing stress measurements. Two different pressurization rates were used in hollow cylinder tests. Tensile strengths were determined to be higher at higher pressurization rate, which suggests that tensile strength should be measurement at the same rate used in actual in situ hydraulic fracturing tests. Considering the effect of pressurization rate and specimen size on tensile strength, the hollow cylinder tests and Brazilian tests yield similar results each other. This demonstrates that Brazilian tests can be utilized to produce representative tensile strengths for interpretation of hydraulic fracturing test results.

수압파쇄법으로 최대수평주응력 크기 규명에 필요한 요소 중 하나인 암반의 인장강도를 측정하는 방법에 대해 연구하였다. 석모도 시추공에서 회수한 화강암 시료에 대해 두 가지 실내시험(중공원통 인장시험 및 압열인장시험)으로 인장강도를 측정하고 두 결과가 차이를 보이는지 비교하였다. 중공원통 인장시험에서는 높은 수압증가율 상태에서 더 높은 인장강도를 보여, 현장의 수압파쇄시험에서 보인 수압 증가율 상태에서 측정된 인장강도나 그 증가율로 보정된 인장강도를 이용해야한다는 점을 보였다. 인장강도에 대한 수압 증가율 효과와 크기효과를 보정하면 중공원통 인장시험 결과는 압열인장시험 결과와 유사하게 나타났으며 이는 수압파쇄 인장강도를 위해 압열인장강도를 이용할 수도 있다는 점을 시사한다.

Keywords

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