Dynamic response of underground structures under blast loads

Three-dimensional nonlinear dynamic responses of underground structures under blast loads induced by explosion of the charge or weapons buried in soil were numerically simulated by use of LS-DYNA3D in this paper. The dynamic finite element model consisted of soil, explosion cavity, a composite structure buried in soil. The composite structure is composed of reinforced concrete liner, shock isolation backfill cushion and surrounding soil. The blast loads were assumed as the empirical pressure time-histories applying to the boundary of the hypothetical explosion cavity. The viscous-spring boundaries were used to simulate the semi-infinite domain of the soil extending away from the edges of the mesh. Comparing with the results of the empirical formula of TM5-855-1, it has been shown that the computational model proposed in this paper were reasonable. The shock isolation effect of the crushable backpacking was also discussed.