Suggestion of dielectric breakdown strength as dynamic fracture property of rock materials

Recently interests in electric pulse power method of mineral processing and borehole drilling have increased. The electric pulse power method is based on the dielectric breakdown inside solid materials by high voltage discharge. The mechanism on the dielectric breakdown includes complicated phenomena such as discharge plasma dynamics, crack propagation and fragmentation. In order to optimize the operation parameters of electrical pulsed power crushing or improve the drilling efficiency, understanding on the effect of rock properties on the dielectric breakdown is significantly important. In this study, the dielectric breakdown strengths of various rocks were investigated and compared with their rock fracture properties such as P-wave velocity, S-wave velocity, and elastic modulus, uniaxial compressive strength in static and dynamic condition. The fracture patterns inside the dielectric breakdown samples were observed by a microfocus X-ray Computed Tomography (CT) scanner.