Simulation and Experimental Study on the Rock-Breaking Process Induced by High-Voltage Electric Pulse

High-voltage electric pulse rock boring (HVEPB) is a high-efficiency rock-breaking drilling technology, which is featured in high rock breaking efficiency and low cost. However, there is no suitable model to predict the high-voltage electric pulses rock-breaking process. First, this paper establishes a grain-based granite model based on Voronoi polygons, which can reflect the real characteristics of granite inhomogeneity. At the same time, based on the improved Wiesmann Zeller model, the electric breakdown channel model is established to simulate the rock electric breakdown discharge channel. Second, a high-voltage electric pulse rock-breaking model is established by combining the shock wave model in the previous research, which can completely predict the HVEPB rock-breaking process and study the influencing factors in the rock-breaking process. Finally, the HVEPB rock-breaking process and the effects of rock composition, electrode bit diameter, and mineral grain size on the rock-breaking are studied by simulation and experiment. The results show that the plasma channel heats up and expands in a quite short time to produce shock waves that act on the surrounding rock, forming crushing fractures and microcracks. Red sandstone is more efficient than granite in breaking rock and is crushed in a shorter period. An increase in drill diameter leads to a decrease in crushing depth and an increase in crushing range and energy utilization. As the mineral grain size decreases, more fractures and smaller grain-size rock debris are produced. The findings are of great importance to guide the commercial application of high-voltage electric pulse rock-breaking.