Optimization Study on Angle of Hydraulic Flushing Hole

In order to study the influece law of flushing hole angle on the effect of hydraulic punching, based on Baimiao Ⅱ₁ coal seam of Henan Pingyu Coal and Electricity Company, we introduce the pressure-relief mechanism of hydraulic flushing borehole. Combined numerical analysis and the field practice, we propose the relationship between angle of the flushing hole and coal output and scope of plastic failure after hydraulic flushing. Research results show that with the increase of punching angle, the coal output and scope of plastic failure present "cosine-like" change law of decrease first and then increase, and the decrease rate is significantly greater than the rate of change.