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Experimental Study on Dynamic Characteristics of Tunnels Crossing Multi-fault Fracture Zones in Strong Earthquake Regions
(1. Key Laboratory of Transportation Tunnel Engineering of the Ministry of Education, Southwest Jiaotong University, Chengdu 610031; 2. Nation Engineering Research Center of Geological Disaster Prevention Technology in Land Transportation, Southwest Jiaotong University, Chengdu 610031; 3. China Railway Eryuan Engineering Group Co., Ltd., Chengdu 610031)
Abstract Based on a tunnel project crossing an active fault zone in a strong earthquake region in western China, the stress of the tunnel structure and the sliding characteristics of the fracture zone in multi-fault fracture zones were studied. The research employed an elastic foundation-based lumped mass mechanical and sliding model. A coupled tunnel-fault model was established using the finite element software combined with infinite element artificial boundaries. Through shaking table experiments, the acceleration response was analyzed to reveal the dynamic response patterns of the surrounding rock and the sliding behavior of multi-fault fracture zones during earthquakes.Results show that the amplification effect of surrounding rock acceleration decreases as the peak ground acceleration (PGA) increases. The difference in peak acceleration values between numerical simulations and experimental results ranges from 6.7% to 13.6%. At the same height along the longitudinal direction of the surrounding rock, the peak acceleration of the soil near the boundary between the fracture zone and the hanging wall or foot wall is the largest. When PGA = 0.4g, the minimum difference between the numerical simulation and the experimental results is 0.8%, indicating that the experimental method can accurately simulate seismic actions. The relative sliding rate γ of the fracture zone was used to evaluate sliding displacement. From the hanging wall to the foot wall, the relative sliding rates between fault surfaces in the fracture zone decreased in theoretical analysis, numerical simulations, and experiments from 30.9%, 33.46%, and 30.63% to 16.5%, 16.17%, and 15.3%, respectively. Sliding displacements within the fracture zones and accumulated shear stresses at fault surfaces decrease progressively.
Abstract：
Based on a tunnel project crossing an active fault zone in a strong earthquake region in western China, the stress of the tunnel structure and the sliding characteristics of the fracture zone in multi-fault fracture zones were studied. The research employed an elastic foundation-based lumped mass mechanical and sliding model. A coupled tunnel-fault model was established using the finite element software combined with infinite element artificial boundaries. Through shaking table experiments, the acceleration response was analyzed to reveal the dynamic response patterns of the surrounding rock and the sliding behavior of multi-fault fracture zones during earthquakes.Results show that the amplification effect of surrounding rock acceleration decreases as the peak ground acceleration (PGA) increases. The difference in peak acceleration values between numerical simulations and experimental results ranges from 6.7% to 13.6%. At the same height along the longitudinal direction of the surrounding rock, the peak acceleration of the soil near the boundary between the fracture zone and the hanging wall or foot wall is the largest. When PGA = 0.4g, the minimum difference between the numerical simulation and the experimental results is 0.8%, indicating that the experimental method can accurately simulate seismic actions. The relative sliding rate γ of the fracture zone was used to evaluate sliding displacement. From the hanging wall to the foot wall, the relative sliding rates between fault surfaces in the fracture zone decreased in theoretical analysis, numerical simulations, and experiments from 30.9%, 33.46%, and 30.63% to 16.5%, 16.17%, and 15.3%, respectively. Sliding displacements within the fracture zones and accumulated shear stresses at fault surfaces decrease progressively.
WANG Haokang1,
2 SHEN Yusheng1,
2 PAN Xiaohai1 etc
.Experimental Study on Dynamic Characteristics of Tunnels Crossing Multi-fault Fracture Zones in Strong Earthquake Regions[J] MODERN TUNNELLING TECHNOLOGY, 2025,V62(1): 212-220
2025, Vol. 62 