<p>The damage mechanism of tunnels under fault dislocation has been widely studied, but fault dislocation and ground motion are inseparable and there are limitations in considering them separately. A stochastic method was developed for the three-dimensional (3D) simulation of strong ground motion, explicitly incorporating the coupling between fault dislocation and seismic wave propagation. The methodology comprises three key steps: first, determining the angles from each sub-source to the station within a finite-fault model; second, calculating the permanent displacement from fault dislocation using layered dislocation theory and deriving the corresponding dynamic displacement waveform function; and finally, integrating this dynamic permanent displacement into the simulated strong ground motion records to achieve the coupling. This research explores the seismic response of tunnels under single and coupled loads, using the Daliang (DL) Tunnel from the Menyuan (MY) earthquake as a case study. A 3D finite element model was established to analyze the structural response under three distinct scenarios: (1) fault dislocation alone, (2) ground motion alone, and (3) the combined action of both. The simulation results indicate that irrespective of the loading condition, tunnel damage is primarily localized at the fault-crossing segment. Applying any single load in isolation underestimates the seismic destructive effect on the tunnel structure. Furthermore, the tunnel deformation under coupled loads significantly exceeds that induced by either fault dislocation or ground motion alone.</p>