Technology of High-Pressure Water Jet Apply in Rock Cross-Cut Fast Uncovering Coal in Serious Outburst Coal Seam

Coal and gas power risk was increased under the condition of high stress, high gas and low permeability of coal seam in deep mine, low permeability coal seam gas pre pumping was very difficult. Drilling enlarging by high-pressure water jet used high pressure water as the driving force to wash and peel the coal body in the drilling, it aimed to discharge the coal and release the gas in the coal seam quickly, the gas pumping efficiency was improved, the stress of coal seam was declined, and the goal of rapid pressure relief and permeability was achieved. It applied in some serious outburst rock cross-cut coal uncovering area, with drilling enlarging by high-pressure water jet technology, drilling equivalent get to 500 similar to 800mm after drilling enlarging, about 3 similar to 9 times of the original diameter, gas extraction concentration was 1 similar to 2 times higher than before, coal uncovering time was shortened by 1/3 similar to 1/2, the effect of field application was obvious.