Damage Mechanism of Tunnels under Strike-Slip and Dip-Slip Fault Misalignment

To study the deformation and failure characteristics of a tunnel under a Aiming at the safety problem of tunnels under complex moving faults, a physical model test with a geometric similarity ratio of 1:35 was carried out on a self-made test platform based on Kangding No.1 tunnel of Sichuan-Tibet Railway tunnel crossing Sehara-Kangding fault engineering. The internal structural displacement and deformation, lining cracking, and strain data of the tunnel were monitored, and the results were analyzed as follows: Under the movement of the strike-slip thrust fault, the tunnel is subjected to shear failure, tensile failure, and torsional failure to a certain extent. At the fault fracture zone, a 45° inclined shear crack appeared in the vault, and a large area of lining shedding was formed. The right waist of the hanging wall (tilting sliding plate) and the left waist of the footwall (strike-sliding movable plate) appear circular tension cracks; About 1.8D (D is the tunnel diameter) from the upper and lower plates is the tunnel shear cracking area. When the strike-slip error momentum reaches 20.7mm (the actual error momentum is 724.5mm), the structural damage accumulates to the limit and large-scale damage begins to occur in the tunnel. The tunnel section converges inward under the pressure of surrounding rock, and the damage of the hanging wall is more serious than that of the footwall in the fault-affected area. Based on the failure characteristics of the tunnel, corresponding anti-slip measures should be proposed, focusing on improving the shear resistance at the fault and the bending and tensile resistance on both sides of the fault.