The Simulation Study of Support Schemes for Transition Zones in Double-Fault Tunnels

When a tunnel passes through the transition zone between two faults, different support schemes have varying impacts on the deformation of the surrounding rock. This study, based on the Zhangzhuang Tunnel's double-fault area, establishes a numerical simulation model using Midas GTS NX to compare and analyze the effects of an enhanced support scheme versus a standard reinforcement scheme. The results indicate that when the non-reinforced support scheme is applied throughout the tunnel, the settlement of the transition zone's crown is 5.7 mm, only 0.27 mm greater than that of the reinforced scheme. Additionally, the variation in support stress in the transition zone between the two schemes is minimal. This demonstrates the feasibility of adopting the non-reinforced scheme, which reduces the number of steel arch frames, enhances construction efficiency, and provides a reference for future construction of small-section tunnels in double-fault conditions.