Theoretical and Numerical Investigation on Rock Fragmentation Under High-Pressure Water-Jet Impact

According to the load characteristics of high-speed water-jet impacting on rock, the hammer pressure, which is a function of time, is regarded as the dynamic load acting on the rock. The theoretical model of rock fragmentation via water-jet impact was set up, and the rock stress and displacement were obtained based on the theory of shock waves. Considering the rock failure criterion and the attenuation characteristic of the stress wave, the scopes of the rock crushing zone and damage zone were established. The numerical model of rock fragmentation via water-jet impact was developed based on the modified maximum principal stress criterion, and the formation of the rock crushing zone, damage zone, radial crack and spall crack was well simulated. The theoretical scopes of the crushing zone and damage zone were slightly smaller than those of the numerical method, because the stress wave reflection and superposition were ignored in the theoretical model. The formation mechanism of the crushing zone, radial crack and spall crack was investigated by analysing the element stress changes as a function of time in different positions.