Abstract: The numerical simulation method to study rock breaking process and mechanism under high pressure water jet was developed with the continuous mechanics and the FEM theory. The rock damage model and the damagecoupling model suited to analyze the whole process of water jet breaking rock were established with continuum damage mechanics and micro damage mechanics. The numerical results show the dynamic response of rock under water jet and the evolvement of hydrodynamic characteristic of jet during rock breaking is close to reality, and indicates that the body of rock damage and breakage under the general continual jet occurs within several milliseconds, the main damage form is tensile damage caused by rock unload and jet impact, and the evolvement of rock damage shows a step-change trend. On the whole, the numerical results can agree with experimental conclusions, which manifest that the analytical method is feasible and can be applied to guide the research and application of jet breaking rock theory.

Key words: water jet, rock breakage, rock damage model, fluid-wall interaction, finite element method