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Modeling of rock dilation and spalling in an underground opening at depth

대심도 지하공동에 발생하는 암반의 팽창 및 스폴링 현상 모델링

Nam-Kak Cho1
,
Yong-Joo* Lee2*
조 남각1
,
이 용주*2*
1(주)서영 엔지니어링 지하공간팀 부장
2서울 산업대학교 건설공학부 조교수
*교신저자. *Corresponding Author. 
31 January 2010. pp. 31-41
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Abstract

This paper presents both numerical and physical modeling approaches for the dilation and spalling of rock recognized as typical process of rock around an underground opening at depth. For physical approach, laboratory testing of rectangular beams using a synthetic rock was used to investigate the onset of dilation and spalling. The beams are axially compressed and subjected to 4-point bending to provide non-uniform compressive stresses which are similar to the maximum tangential stress distribution around circular openings. Discrete element numerical analyses using commercial code PFC2D (Particle Flow Code) were performed to evaluate the stress path at various locations in the beams. The findings from these approaches suggest that the onset of dilation in laboratory tests appears to be a good indicator for assessing the stress magnitudes required to initiate spalling.

Keywords
Dilation
spalling
PFC
discrete element method
4-point bending

본 연구에서는 실험 및 수치해석적인 접근방법을 통하여 대심도 과지압 구간에서 발생하는 암반의 스폴링(spalling) 및 팽창모드에 대한 모델링 기법을 연구하였다. 이에 대한 실험적 접근 방법으로서 축 방향 압축을 받는 직사각형 인공암석 보(beam)에 4점 휨 시험을 결합한 축방향 압축 휨 시험을 수행하여 대심도 지하공간의 응력모드와 유사한 조건 하에서의 암석의 균열 팽창 및 스폴링 과정을 고찰하였다. 또한, 수치해석적 접근방법으로서 기존의 연속체 해석으로는 모사하기 힘든 암석의 균열과정 및 팽창특성을 개별 입자해석 프로그램인 PFC2D를 이용하여 모델링 하였다. 본 연구 결과 휨 실험에서 구한 팽창시점은 스폴링에 요구되는 응력수준을 평가하는데 중요한 지표가 됨을 알 수 있었으며, 또한 수치해석 결과도 유사한 결과를 모사할 수 있음을 보여주었다.

키워드
암석팽창
스폴링
PFC
불연속체 해석
DEM
4점 휨 시험
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https://cdn.apub.kr/journalsite/sites/kta/2010-012-01/N0550120103/images/PICD782.gif
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Information
  • Publisher :Korean Tunneling and Underground Space Association
  • Publisher(Ko) :한국터널지하공간학회
  • Journal Title :Journal of Korean Tunnelling and Underground Space Association
  • Journal Title(Ko) :한국터널지하공간학회 논문집
  • Volume : 12
  • No :1
  • Pages :31-41
  • Received Date : 2009-08-26
  • Revised Date : 2009-10-19
  • Accepted Date : 2009-10-20
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