Dynamic Response Characteristics of Assembled Frame Tunnel Structures under a Surface Explosion: A Numerical Study

Abstract

The vulnerability of assembled tunnels to the explosion load has received little attention although assembled tunnels are less monolithic and are subject to more severe damage under an explosion load. In this study, a three-dimensional refined numerical model was established using a coupled-Euler–Lagrange flow-solid coupling algorithm concerning an actual assembly frame tunnel. The dynamic response of the assembly frame tunnel under surface explosion was studied, and the influence of explosive equivalent, tunnel buried depth, and detonation position on the structural response of the assembled frame tunnel was analyzed. The results show that the poor integrity between the longitudinal ring segments of assembled frame tunnels tends to produce stress concentrations at the longitudinal joints under the explosion load. The explosive equivalent and the tunnel buried depth will change the damage degree of the tunnel but have little effect on the dynamic response of the tunnel. The detonation position has a great influence on the dynamic response of the tunnel. When the detonation occurs directly above the middle partition wall, the damage to the circumferential joints of the side walls exacerbates, necessitating stronger protection of these joints to enhance the tunnel’s resistance to detonation.