Study on the Impact Zoning and Fortification Range of Tunnel Structures Crossing Strike-slip Faults
To address the issue of impact zoning and fortification range for tunnels crossing strike-slip faults,a tunnel in a high-altitude and high-intensity area with active faults was studied.Using finite difference numerical simula-tion,the strain,deformation,and internal force characteristics of tunnel structures under strike-slip fault dislocation were analyzed.Impact zones and corresponding zoning were proposed,and a physical model test of the tunnel was conducted to validate the fault dislocation failure mechanisms and structural response characteristics.The impact scope and patterns induced by fault dislocation were determined.The results indicate that under strike-slip fault dislocation,the tunnel primarily undergoes horizontal compressive deformation at the arch haunch.As fault disloca-tion increases,deformation continues to grow,but the rate of growth decreases.The impact zones are divided into three categories:primary impact zone,secondary impact zone,and stable zone.The primary impact zone includes ranges of 1.4D on the fixed fault wall,2.1D on the active fault wall,and the entire fault zone(where D is the tunnel span).The secondary impact zone on the active fault wall ranges from 2.1D to 6.3D,while other areas fall into the stable zone.Maximum shear stress is concentrated in the fault dislocation-affected zone,which requires enhanced fault dislocation-resisting design.The fault zone exhibits a stepwise decrease in displacement due to the joint dis-placement of the active wall,with the interface between the upper and lower walls and fault serving as the main sliding surface.Relative dislocation within the fault zone is minimal,and the tunnel structure's affected range includes the fault zone interior,0.7D on the upper wall,and 1.5D on the lower wall.
Railway tunnelStrike-slip active faultImpact zoningProtection scopeNumerical simulationModel test
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