Effect of the electrode spacing on dynamic fracture behavior of red sandstone under high-voltage pulse discharge

High voltage pulse technology has broad application prospects in the field of rock fragmentation. Electrical breakdown experiments of red sandstone under the action of high-voltage pulse discharge (HVPD) at different electrode spacings were conducted. The current waveform was recorded using a Rogowski coil. The fracture process on the specimen surface was observed by using an ultra-high-speed camera. The stress wave generated by HVPD was obtained. The experimental results show that both the peak values of the current wave and the stress wave decrease with the increase of the electrode spacing. The surface fracture of the specimen is dominated by transverse fractures parallel to the electrode axis, accompanied by shorter vertical fractures that are perpendicular to the electrode axis. The numerical model is further established to elucidate the three-dimensional fracture process and mechanism of the specimens, and the influence of the electrode spacing on the degree of fracturing is expounded.