Fracture and fragmentation of granite specimen under high-voltage pulses

The high-voltage pulse technique is considered as a promising method for rock fragmentation in rock engineering. Understanding the fracture modes and fragment distribution of rocks subjected to high-voltage pulses is thus essential. In this work, a circuit system for rock breaking by high-voltage pulses discharge was established. The fracturing effect on granite under high-voltage pulses was explored and changes in the median size of fragments with specimen size, charge voltage, and energy density were investigated. The results showed that a breakdown, radial crack, and circumferential crack zone are formed within granite specimens. With the growth of specimen sizes, the average breakdown voltage of granite shows only a marginal change, and the median size of fragments gradually increases. As the charge voltage increases, the median size of fragments is reduced. Additionally, the median size of the fragments attenuates exponentially with the energy density. Furthermore, microscopic analysis using a scanning electron microscope indicated that high-temperature melting and shock waves are the dominant factors in inducing rock fracturing.