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<p>Rock joints, which govern the dynamic behavior of rock masses, are further influenced by weathering, which amplifies their anisotropic characteristics and significantly impacts the stability of underground structures. The increased complexity of joint behavior under dynamic loading necessitates a deep understanding of the response of jointed rock masses to non-uniform dynamic stresses. This study examines the seismic performance of tunnels within the underground research laboratory using a cross-tunnel model that includes an access tunnel, a central hall, and two experimental tunnels. A 3D terrain model was developed using the distinct element method (DEM), with discontinuities explicitly represented through a discrete fracture network (DFN) interlay, simulating weak rock zones through a joint matrix. The DEM-DFN framework models block interactions through dynamic force–displacement calculations, accounting for contact mechanics and large deformation. The continuously yielding rock joint Model simulates the stress-dependent, non-linear shear response of fractures, accounting for dilation and degradation effects. The analysis evaluates the effects of weathering on rock mass stability by comparing the seismic responses of a fresh joint matrix (FJM) and a weathered joint matrix (WJM). Results indicate that the WJM in the access tunnel exhibited higher shear strains and increased susceptibility to seismic loading, while the FJM showed enhanced stiffness and stability. In contrast, the WJM exhibited larger hysteresis loops and potential for block detachment in the main tunnel. Experimental tunnels showed minimal strain and stress, suggesting stable behaviour. Stress path analysis highlighted significantly higher stress concentrations in the WJM, particularly at the crown and spring-line, leading to potential shear and tensile failures. The FJM generally maintained stable stress paths but was more prone to tensile stresses under certain conditions. Displacement analysis demonstrated that the WJM resulted in larger displacements (up to 0.15&#xa0;m) within the first 10&#xa0;s of seismic loading, compared to the FJM. These findings emphasise the critical role of joint weathering in influencing tunnel stability and the importance of incorporating weathering effects in seismic performance evaluations.</p>

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Seismic Analysis of Cross-Tunnels in Jointed Weak Rock Using a DEM-DFN Approach

  • 期刊论文

  • 发表日期：

    2025年5月16日

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  • V. K. Kota,
  • A. Juneja,
  • R. K. Bajpai,
  • G. Prabhakar,
  • P. Srivastava

摘要

Rock joints, which govern the dynamic behavior of rock masses, are further influenced by weathering, which amplifies their anisotropic characteristics and significantly impacts the stability of underground structures. The increased complexity of joint behavior under dynamic loading necessitates a deep understanding of the response of jointed rock masses to non-uniform dynamic stresses. This study examines the seismic performance of tunnels within the underground research laboratory using a cross-tunnel model that includes an access tunnel, a central hall, and two experimental tunnels. A 3D terrain model was developed using the distinct element method (DEM), with discontinuities explicitly represented through a discrete fracture network (DFN) interlay, simulating weak rock zones through a joint matrix. The DEM-DFN framework models block interactions through dynamic force–displacement calculations, accounting for contact mechanics and large deformation. The continuously yielding rock joint Model simulates the stress-dependent, non-linear shear response of fractures, accounting for dilation and degradation effects. The analysis evaluates the effects of weathering on rock mass stability by comparing the seismic responses of a fresh joint matrix (FJM) and a weathered joint matrix (WJM). Results indicate that the WJM in the access tunnel exhibited higher shear strains and increased susceptibility to seismic loading, while the FJM showed enhanced stiffness and stability. In contrast, the WJM exhibited larger hysteresis loops and potential for block detachment in the main tunnel. Experimental tunnels showed minimal strain and stress, suggesting stable behaviour. Stress path analysis highlighted significantly higher stress concentrations in the WJM, particularly at the crown and spring-line, leading to potential shear and tensile failures. The FJM generally maintained stable stress paths but was more prone to tensile stresses under certain conditions. Displacement analysis demonstrated that the WJM resulted in larger displacements (up to 0.15 m) within the first 10 s of seismic loading, compared to the FJM. These findings emphasise the critical role of joint weathering in influencing tunnel stability and the importance of incorporating weathering effects in seismic performance evaluations.