Dynamic Response of Anchorage Chamber under Simultaneous Explosion Load from Top and Side of Arch

Based on the similar model test, the stress wave propagation rule, crack formation mechanism and displacement distribution characteristics of rock mass in the underground anchorage chamber under the simultaneous explosion of concentrated explosive source at top and side of arch are studied by explicit nonlinear dynamic analysis program LS-DYNA3D. By comparing and analyzing the compressive stress time-history curves of the experimental and calculation model, it is found that the simulation results are consistent with the experimental results and conform to the stress wave propagation law, which indicates that the numerical simulation results are reliable. Under explosion of the source, the stress wave propagates to the surrounding rock mass in a circular way. When the stress wave is transmitted to the free surface, it will be reflected and form the stretching wave, which forms the phenomenon of “spalling crack” under the ground and above the tunnel. There are cracks extending along the radial direction of the chamber at the middle point of the explosion source on the top and side of arch. The bolt can play a role in strengthening the rock mass. The distribution of cracks in the anchorage chamber is less than that in the unanchored chamber. The displacement peak value of the surrounding rock at the radial axes of the two blasting sources is the largest and most easily destroyed.