Research On The Mechanism Of Coal Failure By High Pressure Water Jet And Outburst Prevention Technique Of Hydraulic Flushing

China is one of the most serious coal and gas outburst disaster country in the world. It has great significance that coal and gas outburst prevention for ensuring coal mine safety and efficient production. In this dissertation, it combins theoretical analysis, numerical simulation and field test investigation.The research purpose is systematic study of coal breaking by high-pressure water jet and hydraulic flushing outburst prevention technology.First, through the reasonable assumptions and simplifications based on the theory research of coal breaking by high-pressure water jet, this dissertation constructing the mechanical analysis model and numerical calculation model of coal breaking by high-pressure water jet.Then, the dissertation established the theory of equations of coal breaking by high-pressure through mechanical analysis. Meanwhile, using LS-DYNA3D software to simulate and analyze the main processes and characteristics of coal breaking by high-pressure water jet in the different water pressure.Finally, researching on the hydraulic flushing as a representative of outburst prevention technique in coal erosion by high-pressure water jet,the dissertation completed coal erosion by high-pressure water jet test and outburst prevention effect experiment with hydraulic flushing, optimized and improved the hydraulic flushing outburst prevention technology.On the role of high pressure water jet coal research show that:the high-pressure water jet erodes coal containing gas mainly experience of coal rupture failure and crack development stage jet erosion stage. Constructing the mechanical analysis model, the dissertation established the theory of equations of coal breaking by high-pressure. Establishing the high pressure water jet of the coal numerical model, the dissertation used LS-DYNA3D software to simulate and analyze high-pressure water jet eroding coal in the different water pressure, in order to obtain the main process and threshold water pressure of high pressure water jet breaking coal. In high-pressure water jet erosion, the damage forms of coal mainly have crushed damage, tensile failure and stress wave damage, and the stress wave expanding the spread effect area in high-pressure water jet erosion coal. The growth curve can be expressed with the relationship between water pressure and high-pressure water jet erosion depth.Completed coal erosion by high-pressure water jet test and outburst prevention effect experiment with hydraulic flushing in PanSan coal mine of Huai Nan, the tests show that the pressure of high pressure water pump is15-20MPa in order to meet water pressure of eroding coal by water jet. In gas extraction with with hydraulic flushing37days later, hydraulic flushing influence radius of13-1coal seam reaches8.5m.Meanwhile,the residual gas pressure go down to1.35MPa,and the residual gas content go down to5.98m3/t.It show that coal seam gas content is significantly lower, hydraulic flushing outburst prevention technique can gets a good outburst elimination. Around the holes from near and far would be formed four regions:gas fully emission region, gas emission region, gas pressure transition region and natural gas region. The hydraulic flushing outburst prevention technology main experiences to the stages of high pressure water jet erosion coal stage, restoring balance stage and gas extraction phase.