The deformation and stress mechanism of water conveyance tunnel crossing strike-slip fault

Based on the Xianglushan water conveyance tunnel of the central Yunnan water diversion project, a large-scale finite element numerical model was established to study the lining deformation and failure mechanism of the Xianglushan water conveyance tunnel under the action of strike-slip faults. The lining damage law of the tunnel was revealed and the corresponding fortification position was proposed. The results show that the displacement distribution of cross-fault tunnel under the action of strike-slip fault generally presents an elongated S-shaped distribution. In the fault fracture zone, the tensile failure is prevented at the arch waist convex from the fault dislocation surface, and the compressive failure is prevented at the concave. The range of compressive and tensile strains is mainly concentrated in the fault fracture zone ± 0.6 times of the width of the fault zone. The shear damage of the top and bottom of the tunnel is relatively close. Therefore, combined with the strain distribution law of the left and right side walls of the tunnel and the maximum shear stress distribution law of the top and bottom of the tunnel, it is considered that the left and right side walls located in the fault fracture zone should prevent tensile and compressive failure, and the top and bottom of the tunnel should prevent shear failure. The results of this study can provide a theoretical reference for the key vulnerable parts of the tunnel.