Study On Coupling Disaster-Causing Characteristics Of Coal Spontaneous Combustion In Goaf Of Goaf Face With Roadway Along Goaf With High Gas

Coupling of gas and coal spontaneous combustion disasters is often faced in the mining process of coal and gas spontaneous combustion coexisting disasters.In this thesis,the Y-type ventilation working face of a coal mine with high gas and easy spontaneous combustion is taken as the research object.The filling body at the goaf entry is seriously damaged and there is a large air leakage.The gas field in the goaf is more complex due to the use of high suction roadway to extract gas.The influences of different ventilation ratios,negative pressure of high suction roadway,horizontal position of high suction roadway,nitrogen injection position and nitrogen injection amount on the distribution of coal spontaneous combustion risk area,gas occurrence and coupling of coal spontaneous combustion and gas disaster area in goaf were studied by numerical simulation method.First of all,to study the extraction from the high pumping pressure to Y type ventilation working face goaf gas field distribution,the influence of the research shows that:when there is strong air leakage along the empty left lane,extraction from the oxidation zone oxygen concentration 8%contour to goaf internal mobile,oxidation zone area is a substantial increase,could rise of goaf coal spontaneous combustion disaster;The gas concentration in goaf is reduced by the high drainage roadway,which makes the gas concentration of 16%contour line under the high drainage roadway move to the working face greatly.The coupling hazard area of the goaf in the Y-type ventilation working face is mainly distributed in the shallow part near the working face and the goaf side with goaf entry retaining side,showing an"L"type distribution.The coupling region moves towards the working face with the increase of height in the caving zone.Gas extraction can reduce the area of coupling disaster area in goaf to a certain extent,but the effect is not significant.Secondly,the effects of ventilation ratio,negative pressure of extraction and horizontal position of high extraction roadway on coupling disasters of coal spontaneous combustion and gas in goaf are simulated respectively.The results show that with the increase of ventilation ratio,the area of goaf oxidation zone,the area of gas explosion concentration and the area of coupling disaster all decrease at first and then increase.The optimum ventilation ratio of Y type working face in a mine was determined to be 5:1.With the increase of suction negative pressure,the area of oxidation zone in goaf fluctuates up and down,the area of gas explosion concentration decreases first and then increases,and the area of coupling disaster also decreases first and then increases.The optimal suction negative pressure in a Y-type working face is determined to be 2000Pa.The horizontal position of high pumping roadway has little influence on the area of coupling disaster in goaf.According to the simulation results,the optimal horizontal position of high pumping roadway in a Y-type working face is determined to be Y=15m.Finally,the nitrogen injection prevention and fire extinguishing technology was adopted,and the nitrogen injection port was set at different places from the main air inlet side to the working face to simulate the effects of nitrogen injection location and amount on coal spontaneous combustion and gas disaster in the goaf.The results show that nitrogen injection can well reduce the area of oxidation zone and coupling disaster area in goaf.The optimal nitrogen injection rate of a Y-type working face is determined to be 1200m~3/h,and the optimal nitrogen injection position is 20m away from the working face.