Numerical simulation on rock fragmentation by discontinuous water-jet using coupled SPH/FEA method

Abstract

To investigate the rock fragmentation mechanism and its influence factors under discontinuous water-jet impact, the fluid-structure coupled smoothed particle hydrodynamics (SPH) and finite element analysis (FEA) was used to simulate the rock fragmentation process. A rate-dependent constitutive model was adopted to describe the mechanical behavior of rock, and the shock equation of state was used to simulate the water-jet. The rock fragmentation statuses under continuous and discontinuous water-jet impact were simulated and compared under the same initial impact energy, and the rock failure mechanisms, such as the crushing zone and crack formation, were investigated through the elements of pressure and stresses as a function of time. The effects of water-liquids distance and length on rock fragmentation by the discontinuous water-jet were also analyzed. With the same energy, the rock fragmentation performance of the discontinuous water-jet was better than that of the continuous water-jet. The failure of the rock crushing zone was mainly caused by plastic behavior; however, the crack propagation presented brittle failure. The “water cushioning effect” would appear when the water-liquids distance was too small, which restricted the impact effect on rock fragmentation. Discontinuous water-jet with a shorter water-liquid length would result in a deeper crushing zone and volume fragmentation of rock.