Mechanical response analysis of tunnels crossing reverse faults under non-uniform seismic inputs

This study systematically investigates the damage characteristics of tunnels under reverse fault dislocation through the establishment of a three-dimensional finite element model for fault-surrounding rock-tunnel interaction, employing non-uniform seismic motion input. The research focuses on analyzing the influence of dislocation displacement, fault zone width, and fault dip angle on damage evolution patterns. The results indicate that: (1) Tunnel damage is predominantly concentrated in the fault core zone, with stress concentration frequently occurring at the haunch areas. Fault displacement constitutes the primary causative factor for tunnel damage. (2) Increased dislocation displacement exacerbates structural damage, exhibiting asymmetric propagation along the axial direction from the fault core; (3) Fault zone width affects stiffness transition gradients, where greater width enhances deformation coordination capacity and mitigates overall lining failure; (4) Under high-dip-angle conditions, particular attention must be paid to axial deformation failure in tunnel structures. The study proposes a novel input methodology, with results providing theoretical references for seismic design of cross-fault tunnels.