Study on the Damage State and Vulnerability of Twin-Channel Tunnels Under Single-Channel Internal Explosions

Tunnels are critical components of transportation networks. Explosions caused by accidents or terrorist attacks can severely damage tunnel linings and even cause structural collapse. This paper develops the validated simulation model for single-channel tunnels into a twin-channel tunnel model. Subsequently, a simulation study investigates the damage state and vulnerability of the twin-channel tunnel under single-sided internal blasting. The results suggest that the supporting effect of the soil can improve the blast resistance of the outer wall of the tunnel. An explosion within a single channel can induce changes in the relative bearing capacity of the twin-channel lining. Under the influence of earth pressure, the relative bearing capacity of the twin-channel lining is further weakened, thereby affecting the overall failure state of the tunnel. Longitudinal plastic strain is primarily distributed at the ends and center of walls and floors, and it spreads as the charge mass increases. The charge location has a significant impact on the damage state of the outside walls of the uncharged channel of the tunnel. Placing explosives on tunnel walls will increase the damage level of the twin-channel tunnel. When the charge weight exceeds 1000 kg and 3000 kg, respectively, the exceedance probability for minor damage and severe damage to the tunnel approaches 1. The strengthening of the blast protection level of the center wall is the key to preventing tunnel collapse.