Dynamic Response and Damage of Subway Tunnels Subjected to Explosion-Induced Loads

The instantaneous strong load generated by an explosion outside of a subway tunnel can destabilize and damage the tunnel’s lining, and thus endanger human safety and property. To avoid this risk, it is necessary to investigate the dynamic response and damage of subway tunnels under explosion-induced loads. This study used the ANSYS/LS-DYNA software to establish the finite element model of a tunnel. The surface side blast angle, tunnel buried depth, and explosive equivalent were the considered variables, and the dynamic response and damage of the tunnel’s lining structure under an external blast-related load were analyzed. The results reveal that, when the side blasting angle was 15°, the tensile strain was 150 on the left side, which means that the horizontal deformation of the lining cannot be ignored. When the buried depth of the tunnel was used as the main variable, the damping effect of the soil medium was obtained by comparing the displacement–time and velocity–time data. This comparison provides a reference for reasonably setting the tunnel depth in similar projects. When the explosive equivalent was considered as the main variable, the overall instability caused by the local damage of the lining structure was analyzed. The findings of this study can be used to improve the design of effective countermeasures and systems for protecting tunnels from external explosions, and have high technical, economic, and social importance and reference value for similar engineering design projects.