Optimization of “hole-drift” collaborative drainage layout parameters and high efficient drainage in pressure relief gas migration area

Gas drainage in high outburst mine is an important means to control the gas overrun in the corner of the working face. The layout levels of each drainage mode are different, and there are obvious differences in the drainage effect. It is of great significance to study the optimal layout levels of each drainage mode of cooperation drainage. To improve the extraction efficiency of high extraction roadway and realize accurate gas extraction, based on the “elliptic paraboloid zone” theory, the layout horizon of each extraction mode of collaborative extraction is simulated and studied by using Fluent numerical simulation software, the gas concentration in the corner of the working face under each layout condition is analyzed, and the optimal layout horizon is determined. The simulation results show that the layout horizon of each extraction mode in collaborative extraction was: the optimal horizontal distance of high extraction roadway was 25 m, the optimal vertical distance was 30 m, the optimal horizontal distance of directional long drilling was 10-20 m, and the optimal vertical distance was 11-21 m. Through the comparative analysis of single extraction and collaborative extraction, in collaborative extraction, the span of the rapid lift zone area on the return air side is significantly increased, which reduces the gas intensity of the return air side flowing into the working face through the upper corner, and the corner gas was further controlled. Cooperative drainage better solves the problem of large accumulation of gas in the upper corner caused by the relative negative pressure caused by the return side wind flow of the working face, and the phenomenon of gas accumulation caused by the corner vortex gradually disappears under long borehole drainage. After the field application of the optimized layout parameters, the average net amount of gas extraction in the high drainage roadway during the production period of the test face is 64.79 m3/min, accounting for 79.91% of the gas emission, and the average net amount of gas extraction in the directional long drilling hole is 9.68 m3/min, which reduces the pressure of air exhaust gas, the maximum gas concentration in the upper corner and return air roadway is controlled within 1%, and the problem of gas overrun in the test face has been effectively controlled, which ensures the safe and efficient production.