The damage effects of the earthquake on tunnels crossing faults are categorized into two types: inertial forces generated by ground motions and permanent stratigraphic deformations caused by fault dislocations. A seismic dynamic analysis method of tunnel considering coseismic dislocation is proposed by introducing the numerical simulation of seismic wave propagation into the soil-structure dynamic analysis research field. First, seismic waves are simulated according to the finite-difference method. The stress, displacement, and velocity of nodes on the truncated boundary of the soil-structure model can be calculated according to the seismic wave propagation simulation method. Then, the seismic waves and dynamic dislocation load are simulated in the finite element model by the viscous-spring boundary. Based on the free-field model, the reliability of the presented method is validated in simulating coseismic deformation and seismic waves. In the case of the 2022 MS 6.9 Menyuan earthquake and the Daliang tunnel, which was severely damaged by this earthquake, the deformation of the tunnel simulated based on the presented method is consistent with the previous method. The proposed method can offer guidance for the seismic fortification of tunnel engineering.

In practical scenarios, tunnels may unavoidably cross active fault zones, leading to potentially severe damage by active fault displacement during earthquakes. Previous studies have failed to clearly establish an analytical method that considers both compressive and frictional behavior between tunnels and the soil that surrounds them, hindering the understanding of the tunnel -soil interaction. To address this, a finite element model (FEM) has been developed in this study to investigate the compressive and frictional characteristics of the tunnel -soil interaction of a reverse active fault -crossing tunnel. The model identifies six distinct zones of tunnel -soil interaction, namely, two active zones, two passive zones, and two separation zones. Building on these findings, the active fault -tunnel system was divided into three equivalent sub -systems, and an analytical method was established by creating and then combining equations for each sub -system. By applying the Pasternak Elastic Foundation Beam theory and Elastic theory, an analytical method is introduced that can simultaneously consider the distributed non-linear compressive interactive stress and non-linear frictional interactive stress. The results of the analytical method were validated with the FE results under three series of geological conditions. Through a quantitative examination of the similarity ratio and length of influence, the analytical results were seen to effectively reflect the characteristics of the soil -tunnel interaction and exhibit a good agreement with the FE results. It is concluded that the analytical model will serve as a computational reference for the design of reverse active fault -crossing tunnels.