터널과지하공간 (Tunnel and Underground Space)

  • 제22권2호
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  • Pages.106-119
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  • 2012
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  • 1225-1275(pISSN)
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  • 2287-1748(eISSN)
한국암반공학회 (Korean Society for Rock Mechanics and Rock Engineering)
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암석 절리면 거칠기의 새로운 3차원 정량화 계수

A New Coefficient for Three Dimensional Quantification of Rock Joint Roughness

  • 박정욱 (한국지질자원연구원 지구환경연구본부) ;
  • 이용기 (서울대학교 에너지시스템공학부) ;
  • 송재준 (서울대학교 에너지시스템공학부) ;
  • 최병희 (한국지질자원연구원 지구환경연구본부)
  • 투고 : 2012.03.20
  • 심사 : 2012.04.09
  • 발행 : 2012.04.30
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초록

암석 절리면의 거칠기는 대부분 2차원 프로파일의 기하학적 특징에 초점을 맞추어 기술되어 왔다. 그러나 거칠기를 합리적으로 평가하기 위해서는 수직 및 전단하중하에서 실제 접촉 상태에 놓여 발현되는 유효 거칠기 특성을 적절히 반영할 수 있어야 한다. 본 연구에서는 편마암 인장 절리의 복제 시험편에 직접전단시험을 수행하고 전단 방향에 따른 강도 및 거칠기 특성을 고찰하였다. 이 과정에서 절리면의 3차원 형상을 삼각형 요소의 집합으로 재구성하고, 각 요소의 거칠기를 전단 방향에 따른 활성, 비활성 미세거�s각을 이용하여 정의하였다. 수치적 알고리즘을 이용하여 최대전단강도 발현 시 접촉면의 위치와 면적을 예측한 결과, 접촉면의 분포는 미세 거�s각의 분포와 밀접한 관계를 보였으며, 활성거�s각을 갖는 요소만이 전단 거동에 주도적인 역할을 수행하였다. 따라서 활성거�s각의 분포 특성을 모사할 수 있는 확률밀도함수를 제시하고, 이 과정에서 얻어지는 활성거칠 기계수 $C_r$을 암석 절리면의 새로운 거칠기 정량화 계수로 제안하였다. 각 시험편에 대한 전단방향에 따른 $C_r$과 실험 결과를 비교한 결과, $C_r$이 절리면의 거칠기를 정량화하고 전단 강도를 예측하는 데 있어 매우 유용한 파라미터임을 확인하였다.

Roughness of rock joint has generally been characterized based upon geometrical aspects of a two-dimensional surface profile. The appropriate description of joint roughness, however, should consider the features of roughness mobilization at contact areas under normal and shear loads. In this study, direct shear tests were conducted on the replicas of tensile fractured gneiss joints and the influence of the shear direction on the shear behavior and effective roughness was examined. In this procedure, a joint surface was represented as a group of triangular planes, and the steepness of each plane was characterized using the concepts of the active and inactive micro-slope angles. The contact areas at peak strength which were estimated by a numerical method showed that the locations of the contact areas were mainly dependent on the distribution of the micro-slope angle and the shear behavior of joint was dominated by only the fractions with active micro-slope angles. Therefore, a three-dimensional coefficient for the quantification of rock joint roughness is proposed based on the distribution of active micro-slope angle: active roughness coefficient, $C_r$. Comparison of the active roughness coefficient and the peak shear strength obtained from the experiment suggests that the active roughness coefficient is the effective parameter to quantify the surface roughness and estimate the shear behavior of rock joint.

키워드

참고문헌

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피인용 문헌

  1. Generation of Roughness Using the Random Midpoint Displacement Method and Its Application to Quantification of Joint Roughness vol.22, pp.3, 2012, https://doi.org/10.7474/TUS.2012.22.3.196
  2. A Study on the Effect of Normal Stress on the Joint Shear Behavior vol.23, pp.3, 2013, https://doi.org/10.7474/TUS.2013.23.3.203
  3. A Study of the Effect of Asperity Change on the Shear Strength of Joint Plane vol.23, pp.5, 2013, https://doi.org/10.7474/TUS.2013.23.5.401
  4. A Numerical Study on the Correlation between Joint Roughness and Hydraulic Characteristics vol.24, pp.2, 2014, https://doi.org/10.7474/TUS.2014.24.2.176