Research on Stress Simulation and Mechanism of Delaying Coal and Gas Outburst in Coal Driving

The "three area" distribution of stress in coal driving is a key factor for delaying the outburst.The stress distribution and range of "three area" were calculated with a RFPA~2D software,and the effect of permeable force on the gas outburst was analyzed.The full stress-relaxed area of 2 m,the partial stress-relaxed area of 2～6 m and stress concentration area of 6～12 m were achieved.The width of stress-relaxed area increases with time because of the strain-softening in coal driving.Coal in the wall falls by the action of gravity when the horizontal carrying capacity is less than the horizontal load,which leads the horizontal load transfers to the deep coal seam to make the stress of it destroyed.And this is a positive feedback acceleration process till the stress destroy wave is formed,and results in the quick failure of the coal seem and the coal and gas outburst.