Numerical Simulation Study On The Effect Of Coal And Gas Outburst On Local Ventilation

Coal and gas outburst is accompanied by a large amount of high-pressure and high-concentration gas emission,which accumulates a large amount of energy before gas emission and forms a high-energy gas flow in the tunnel after instantaneous gas emission.When the high-energy gas flow is opposite to the direction of the incoming wind,the gas counter-current will occur.Mastering the mechanism of gas migration and diffusion after disaster has important practical significance for controlling the influence range of gas disaster,rationally arranging rescue after disaster and reducing the occurrence of secondary disasters such as gas explosion and suffocation caused by gas over limit.By analyzing several cases of coal and gas outburst,this paper summarizes the dynamic effect after gas outburst and the characteristics of gas migration along the ventilation system after gas outburst.The influence of coal and gas outburst scale,outburst position,state of anti-outburst damper and damper of connecting roadway on gas flow after outburst is simulated under the condition of dual roadway driving.When the head of the intake air tunnel protruded,the damage to the damper and the countercurrent distance were obviously greater than that of the head of the return air tunnel.A pressure of 2.1 1Mpa can be generated at the damper during extra-large scale outburst.The damper design should be greater than the pressure to effectively prevent gas counterflow.At the same time,if the strength of the damper at the contact lane is insufficient or no damper,it will also lead to gas outburst countercurrent.The paper simulates the mutual influence of coal and gas outburst on the mining face and the driving face when the double-wing mining area is arranged.It is concluded that the coal and gas outburst on the mining face mainly affects the adjacent driving face through the inlet and countercurrent,and the driving face outburst affects the working face in the mining area through the return air.Mining area the size of the return air resistance on the happening of the upstream influence obviously,when the return air resistance is less than 30%of the total resistance,outstanding after most of the gas to be able to return air lane,through mining area of a smaller effect on working face into the wind lane when return air resistance is greater than 70%of the total resistance,gas can't highlight by mining in return air lane,cause gas upstream face into the wind,full and quickly into the wind tunnel.Based on the results of numerical simulation,this paper puts forward some anti-gas counter-current measures such as gas outburst monitoring and control,and puts forward some methods and technical measures for ventilation system reliability optimization.It is helpful for the outburst of gas to discharge the mine quickly,reduce or avoid the gas countercurrent after coal and gas outburst,and quickly restore the normal ventilation of the mine.