Mechanical of breaking coal by water jet

Supposed that the elastic modulus and compressive strength of inhomogeneity rock mess cells conform to Weibull distribution.Deduced breaking rule of inhomogeneity rock mess by water jet and the threshold pressure of water jet with percolation theory,numerical simulated continuous drilling in the inhomogeneity coal by water jet with finite elements method and the experiment of breaking coal by water jet was carried out.The study indicates that under water jet,the low strength cells in inhomogeneity rock mess are first destroyed,a crack is created under water jet,the effect of the water wedge occurring by water jet which enters the crack space producing tensile stress concentration at the tip of a crack,so the cracks expand rapidly and converge gradually,eventually the rocks mess are fragmented,a cracked pit is formed.The cracked distance of coal by water jet at 60 MPa is more than 0.5 m.