Journal of Korean Tunnelling and Underground Space Association (한국터널지하공간학회 논문집)

Korean Tunnelling and Underground Space Association (한국터널지하공간학회)
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A numerical analysis study on the effects of rock mass anisotropy on tunnel excavation

암반의 이방성이 터널 굴착에 미치는 영향에 대한 수치해석적 연구

  • Ji-Seok Yun (Dept. of Smartcity Engineering, Hanyang University) ;
  • Sang-Hyeok Shin (Dept. of Smartcity Engineering, Hanyang University) ;
  • Han-Eol Kim (Dept. of Geotechical Engineering, Korea Institute of Civil Engineering and Building Technology) ;
  • Han-Kyu Yoo (Dept. of Civil and Environmental Engineering, Hanyang University)
  • 윤지석 (한양대학교 스마트시티공학과) ;
  • 신상혁 (한양대학교 스마트시티공학과) ;
  • 김한얼 (한국건설기술연구원 지반연구본부) ;
  • 유한규 (한양대학교 건설환경공학과)
  • Received : 2024.05.28
  • Accepted : 2024.06.05
  • Published : 2024.07.31
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Abstract

In general tunnel design and analysis, rock masses are often assumed to be isotropic. Under isotropic conditions, material properties are uniform in all directions, leading to a higher evaluation of tunnel stability. However, actual rock masses exhibit anisotropic characteristics due to discontinuities such as joints, bedding planes, and faults, which cause material properties to vary with direction. This anisotropy significantly affects the stress distribution during tunnel excavation, leading to non-uniform deformation and increased risk of damage. Therefore, thorough pre-analysis is essential. This study analyzes the displacement and stress changes occurring during tunnel excavation based on rock anisotropy. A three-dimensional numerical analysis was performed, selecting anisotropy index and dip angles as variables. The results showed that as the anisotropy index increased, the displacement in the tunnel increased, and stress concentration became more pronounced. The maximum displacement and shear stress were observed where the dip planes met the tunnel.

일반적인 터널 설계 및 해석 시 암반을 등방성으로 가정하나, 등방성 조건에서는 재료특성이 모든 방향에서 균일하므로 터널의 안정성이 높게 평가되는 경향이 있다. 그러나 실제 암반은 절리, 층리, 단층 등 불연속면이 존재하며 방향에 따라 재료의 특성이 다른 이방성 특징을 가진다. 이러한 암반의 이방성은 터널 굴착 시 발생하는 응력 분포에 큰 영향을 미쳐, 불균일한 터널 변형을 유발하고 손상 위험을 증가시키기 때문에 사전에 철저한 분석이 필요하다. 본 연구에서는 암반의 이방성에 따라 굴착 과정에서 발생하는 막장면과 터널이 굴착된 후 수렴된 위치에서 발생하는 변형과 응력 변화에 초점을 두었다. 탄성계수의 비율(E1/E2)에 따른 이방성지수(IE)와 경사각을 변수로 선정하여 3차원 수치해석을 수행하였다. 결과적으로 이방성 지수가 증가할수록 터널에서 발생하는 변위가 증가하고 응력집중 현상이 크게 발생하였으며, 경사면이 터널과 접하는 부분에서 최대 변위가 발생하고 전단응력이 가장 크게 발생하는 것을 확인하였다.

Keywords

Acknowledgement

본 연구는 국토교통부(국토교통과학기술진흥원) 건설기술연구사업의 '도심 지하 교통 인프라 건설 및 운영 기술 고도화 연구(RS-2020-KA157786)' 연구단의 지원으로 수행되었으며 이에 깊은 감사를 드립니다.

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