Micro-mechanism study on rock breaking behavior under water jet impact using coupled SPH-FEM/DEM method with Voronoi grains

Abstract

In this study, a two-dimensional SPH-FEM/DEM coupled model is developed to investigate rock breaking behavior under water jet impact based on the LS-DYNA software, where the SPH method is adopted to model the water jet and the FEM/DEM method is adopted to simulate rock breaking response, respectively. To better approximate the micro-structure of rock, a Voronoi tessellation technique is adopted to generate the random polygonal grains. A zero-thickness cohesive element is inserted along the boundaries of the Voronoi grains to model the mechanical interaction between grains as well as the breaking process of rock. Numerical water jet impact tests on sandstone are firstly conducted to verify the proposed method as well as calibrate the corresponding micro-parameters. Then, using the verified method, the effects of micro-structure and micro-mechanical properties on the rock breaking performance under water jet impact are systematically investigated. The numerical results show that the rock breaking performance is greatly affected by grain size and irregularity, ductility, microscopic strength and the heterogeneity of micro-parameters, whereas the contact stiffness ratio has little effect on the rock breaking performance under water jet impact.