Analysis of rock-breaking mechanisms of high-voltage pulsed electric electrode bits

High-voltage pulsed electric rock-breaking technology is an innovative, green, and efficient method with substantial potential in the field of rock fragmentation. The efficiency of this technology is primarily determined by the design of the electrode bit. To investigate the impact of electrode bit design on rock fragmentation, this study developed a three-dimensional electro-rock breaking model based on the coupling of multiple fields: current field, electrostatic field, breakdown field, heat transfer field, and solid mechanics field. Using this comprehensive three-dimensional model, we conducted dynamic electrical breakdown simulations of granite, incorporating five different electrode bit structures and six degrees of rock heterogeneity. The simulation results elucidate the effects of pulsed peak voltage, granite heterogeneity H , and electrode bit structure on the efficiency of high-voltage pulsed electric rock breaking. To validate the simulation results, laboratory experiments on electro-rock breaking were performed. The experimental findings indicate that the conical electrode bit exhibited the highest rock-breaking efficiency, while the pentagonal prism-shaped electrode bit showed the poorest performance. The tip of prismatic electrodes generates a tip discharge effect; for the triangular prism, this effect often results in irregular rock fragmentation, which is detrimental to drilling efficiency. These results highlight the significant influence of electrode shape on rocks' electrical breakdown and fragmentation. This study provides valuable insights into the engineering application of high-voltage pulsed electric rock-breaking technology.