Numerical Investigation of Dynamic Response of a Cross-Fault Tunnel Surrounding Rock Subject to Earthquake Excitation

Traffic tunnel engineering is an important lifeline engineering in the world, which has a great risk of destruction during earthquakes. It is of great significance to ensure their safe and reliable operation subject to earthquakes. The interaction between seismic loads and complex geological conditions results in complex dynamic responses of tunnels across faults. In this work, the research progress of seismic response of cross-fault tunnel is analyzed, and the influencing factors of earthquake damage are summarized. In addition, three-dimensional dynamic analysis is used to study the dynamic characteristics of a cross-fault tunnel. The results show that the influence factors of earthquake damage of cross-fault tunnel mainly include surrounding rock properties, fault parameters, ground motion parameters and tunnel buried depth. The direction of seismic wave affects the propagation characteristics of wave in tunnel surrounding rock. Geological conditions have impacts on the earthquake response of surrounding rock. The dynamic amplification effect of surrounding rock of cross-fault segment decreases with the increase of tunnel lining elevation, and the dynamic amplification effect of intact surrounding rock is different from that of cross-fault segment. The input directions of ground motion has effects on the seismic amplification effect of surrounding rock, and the dynamic amplification effect of horizontal ground motion is greater than that of vertical ground motion. This research work has reference function for earthquake reinforcement measures of tunnel engineering.