(1. College of Energy and Safety，Anhui University of Science and Technology，Huainan，Anhui 232001，China；2. Key Laboratory of Mine Safety and High Efficient Mining Jointly Built by Province and Education Ministry，Anhui University of Science and Technology，Huainan，Anhui 232001，China；3. Center for Rock Instability and Seismicity Research，Dalian University of Technology，Dalian，Liaoning 116024，China；4. Dalian Mechsoft Co.，Ltd.，Dalian，Liaoning 116600，China)
Abstract：In order to get the rule of the cranny development，stress field evolution and the high-pressure water flowing in the coal seam from a microscopic view，besides fieldwork experimentation about the high-pressure water injection in the coal seam of working face 721 in Qinan Coal Mine，numerical simulation is studied by the RFPA2D-Flow code developed on the basis of the solid-flow coupling dynamic model，in which the heterogeneity characteristics of the mechanical properties of coal and rock and the nonlinear evolution characteristics of gas permeability in stressed coal and rock are considered and incorporated. According to the numerical simulation，the seepage ability of the coal body around the infusing borehole becomes greatly stronger as a result of its gradual damage and cranny expanding under the effect of the high pressure water. The value of the maximal seepage parameter of the coal body could increase from 0.5 m/d to 1 580.0 m/d and 14 times averagely in part. According to the fieldwork experimentation，after adopting the high-pressure water injection technology，the width of the stress-relaxed zone at the front of the working face increases form 2.5 m to 3.5 m and the stress concentration zone moves to the deeper position for 1.0 m，which shows that the effect of the high-pressure water injection on eliminating the coal and gas outburst is comparatively considerable.
