Mechanical Response Study of a Cross-Fault Water Conveyance Tunnel under the Combined Action of Faulting Dislocation and Seismic Loading

This paper investigated the response of a cross-fault water conveyance tunnel under the combined action of faulting dislocation and seismic loading. The current work studied the mechanical properties of the wall rock–lining contact surface. Finite difference method (FDM) code was used for the numerical simulation test to reproduce the shear test and calibrate the parameters. In the analysis of the combined faulting dislocation and strong earthquake impact on the cross-fault tunnel, the FDM was used with special consideration of the wall rock–lining interaction. The result showed that the Coulomb contact model in the FDM code could satisfactorily simulate the shear behavior of wall rock–lining contact surface. In the mechanical response calculation of the cross-fault tunnel under the faulting dislocation–seismic loading action, the magnitude of the initial faulting distance had a significant effect on the seismic relative deformation of the tunnel. The permanent deformation caused by the seismic loading increased with the initial faulting dislocation. The position of the maximum shear stress on the contact interface was related to the faulting dislocation mode, and it was distributed on the side of the tunnel squeezed by the active plate. In the high seismic risk regions with extensive development of active faults, it was necessary to consider the initial crack caused by the faulting dislocation in the stability evaluation of the cross-fault tunnel. Then, the seismic resistance study of the tunnel was followed.