The response characteristics of fault-crossing tunnel subjected to different sequential combination actions of strike-slip fault dislocation and seismic wave propagation

The combined effects of fault dislocation and earthquake activity on fault-crossing tunnels present significant risks to both construction and operational safety. However, the interaction between fault dislocation and earthquake motion remains inadequately understood, necessitating an investigation into the lining response characteristics of fault-crossing tunnels exposed to combinations of these two factors. This study utilized a representative long fault-crossing tunnel in western China to develop and validate a three-dimensional numerical analysis model, which was verified against physical similarity model experiments on fault dislocation response. Comparative analyses were performed to explore the tunnel lining's response to fault dislocation, Dislocation-Earthquake sequential combinations (D-E), earthquake activity, and Earthquake-Dislocation sequential combinations (E-D). Additionally, a detailed parametric sensitivity analysis was performed to examine the tunnel lining's internal force responses under both sequential combination actions. Results indicated that the tunnel lining's response to fault dislocation, based on a model that incorporated geological structural zoning within the fault zone (including fault fracture zone, fault core, and fault influence zone), aligned closely with deformation patterns observed in post-earthquake field investigations. Fault dislocation is the dominant factor causing the lining structures damage both in the sequential combinations of E-D and D-E, although the earthquake action can contribute a corresponding amplification of the stress responses in the sequential combinations of D-E. Furthermore, internal force responses of the tunnel lining exhibit heightened sensitivity to variations in fault dip angle under both sequential combinations. The effect of fault dip angle, fault core width, and fault core location on the lining's internal forces differ, reflecting the predominant influence of the specific actions in each combination.