Influence of Water Depth on the Range of Crushed Zones and Cracked Zones for Underwater Rock Drilling and Blasting

Abstract

In this paper, the theoretical radii of the crushed and cracked zones for underwater rock drilling and blasting with coupling charge under different water depths were computed, and the dynamic finite-element software LS-DYNA was employed to simulate the failure zone of underwater rock drilling and blasting. The results show that the ranges of the crushed and cracked zones in the shallow water condition are slightly larger than those in the waterless condition. This is because the strength of the underwater saturated rock mass is lower than that of the rock mass under the waterless condition, which causes a slight increase in the range of the crushed and cracked zones after blasting. With increasing water depth, the effect of water pressure becomes increasingly obvious; in particular, the water pressure inhibits circumferential tensile stress induced by blasting, resulting in a rapid decrease in the range of the cracked zone. According to the simulation results, the peak value of the blasting vibration increases with the water depth because the generation of the cracked zone is inhibited by the action of water pressure; thus, more blasting energy is dissipated in the form of elastic vibration.