Effect of water jet geometric parameters on rock fracturing

Abstract

Fluid-driven rock fracturing has been attempted in the fields of mining and civil engineering. This type of rock fracturing is initiated by applying high-pressure water to target rock. In this study, the fracturing characteristics of hard granite specimens were explored through experimental tests using a high-pressure water jet system. Various tests were performed to evaluate the effects of several geometric parameters: standoff distance, indentation depth, and free surface condition. The fracture depth, radius, volume, and angle were measured, and then analyzed to investigate the fracturing characteristics. In addition, we prepared a theoretical estimate of maximum shear stress via shear stress analysis using a crack-tip stress field model. In these experimental and theoretical studies, efficient rock fracturing was demonstrated with a combination of short standoff distance, deep indentation, and nearby free surfaces. Meanwhile, the fracture angle for infinite free surface boundary specimens was identified as a unique value regardless of the standoff distance and indentation depth.