Numerical Simulation of Effective Extraction Influence Radius of Soft and Hard Coal Under Different Negative Pressure

The effective extraction influence radius is an important pursuance on determining the borehole layout parameters and evaluating drainage effect,accurate determination of which has important value in coal and gas outburst prevention.In order to determine the reasonable parameters of gas drainage for No.2₁ coal seam in Jiulishan coal mine,it implements calculation and comparative analysis for effective extraction influence radius of soft and hard coal under different negative pressure by using the numerical simulation.