Experimental Research on High-Voltage Electric Pulse Rock-Breaking Performance

Summary High-voltage electric pulse (HVEP) drilling technology offers advantages such as high rock-breaking efficiency and low energy consumption. However, its effectiveness is influenced by parameters including pulse voltage magnitude and the shape and structure of the high-voltage electrode drill bit (HVED). Currently, there is limited research on the mechanisms by which high pulse voltages (>100 kV) affect rock dielectric breakdown and the patterns of pulse voltage generation. To better reflect the impact of various parameters on rock-breaking performance during HVEP drilling, this study conducts laboratory experiments on HVEP rock breaking. The effects of pulse voltage magnitude, different rock samples, and various HVED shapes on HVEP rock-breaking efficiency were investigated. The experimental results indicate that the cracks generated after the electric pulse breakdown of rock are predominantly tensile, with a hackly pattern, and propagate to significant depths. When shear cracks form inside the rock, they predominantly propagate as small crack growths, resulting in a larger area of the rock being affected by the cracks. The pentagonal prism-shaped HVED exhibited the highest average standard deviation in rock-breaking performance, indicating the greatest variability. Cylindrical and conical HVEDs showed better rock-breaking performance with deeper fractures, though concave surfaces were observed in the center of the fractures. Triangular and quadrangular prism-shaped HVEDs demonstrated the most consistent rock-breaking quality. In addition, increasing the electrode bit diameter reduced the maximum electric field strength within the rock, increased the average electric field strength, and expanded the breaking range. This study provides valuable insights for the development of electric pulse rock-breaking tools and the advancement of HVEP drilling technology.