Optimal simulation research on gas extraction parameters of long boreholes in roof strike of Sihe Mine

In order to solve the problem of gas overrun in the upper corner of the 5309 working face of Sihe Mine, gas control is carried out by means of gas extraction with long boreholes in roof strike.FLUENT software is used to simulate and analyze the gas extraction effect under different parameters of the roof long borehole cluster arranged in the horizontal return airway with hole spacing of 10 m.The result shows that: as the vertical distance between the long borehole bundle and the bottom plate along the roof strike increases, the pure gas flow rate of borehole drainage increases first and then decreases, and the gas concentration in the upper corner shows an increasing trend; with the increase of the horizontal distance between the long borehole bundle and the return airway along the roof strike, the pure gas flow rate of borehole drainage increases first and then decreases, and the gas concentration in the upper corner first decreases and then increases.After comparative analysis, it is determined that the best extraction position of the long borehole bundle with the roof strike is 38 m from the vertical height of the roof and 25 m from the return airway.The pure gas flow rate of the boreholes can reach 15.03 m³/min.The gas concentration in the upper corner of the 5309 working face is reduced to 0.20% and the gas treatment effect is significant.