Mechanical Behavior and Damage Evolution of a Fabricated Rectangular Tunnel with a Mortise-and-Tenon Joint under Internal Explosion

A new mortise-and-tenon joint for a fabricated rectangular tunnel is designed in this study. To explore the damage evolution of a fabricated rectangular tunnel with a mortise-and-tenon joint under internal explosion, a refined numerical model is established by using Abaqus finite element software. The sensitivity of the explosion resistance of a rectangular tunnel to different trinitrotoluene (TNT) equivalents, concrete strength grades, scaled distances, and types of joints is analyzed. The spatiotemporal effect and damage characteristics of the fabricated rectangular tunnel after a central explosion are discussed. Finally, the deformation characteristics of the tunnel corner are quantified by defining a tunnel deformation angle. The results show that the tunnel is more sensitive to the explosion equivalent and less sensitive to the concrete strength grade, and the tunnel roof is highly sensitive to TNT at different distances. The damage of the fabricated rectangular tunnel under an explosion wave has significant spatiotemporal evolution characteristics. The roof and floor of the tunnel are first impacted by explosion, and their reflection on the explosion wave will significantly enhance the explosion effect. The joint of the prefabricated tunnel has small stiffness and large flexibility, and the reflection enhancement effect on the shock wave is weak. The impact of explosive waves results in tensile stresses on the outside of the roof and floor of the tunnel and on the connection of the midpartition, where the explosion resistance is weak. The tunnel deformation angle is used to quantify the deformation damage characteristics of the tunnel. The results show that the safety height of the vehicle in the tunnel should be controlled within 3.8 m. The current research provides some valuable information for the future antiexplosion design and evaluation of the prefabricated frame tunnel.