Study On Coupling Disaster Of Gas And Coal Spontaneous Combustion In Goaf Under The Condition Of High Drainage Roadway

Over the years,the mine gas explosion and coal spontaneous combustion disaster have seriously affected the safety,efficiency and normal mining of the mine.However,high drainage roadway drainage will change the air leakage field in the goaf and increase the air leakage in the goaf.In this case,not only the oxygen concentration distribution state of the goaf changes,but also the gas concentration distribution will change,which will affect the occurrence of coupling disaster of gas and coal spontaneous combustion in the goaf under certain conditions.Therefore,this paper mainly studies the change rules of goaf gas concentration,goaf oxygen concentration,goaf gas and coal spontaneous combustion coupling disaster risk area under different working face air supply volume,different layers of high drainage roadway,and different negative pressure drainage conditions of high drainage roadway through numerical simulation.From the Angle of preventing and controlling the coupling hazard of gas and coal spontaneous combustion in goaf,it is particularly important to determine the reasonable position of high drainage roadway,reasonable air supply of working face and reasonable negative pressure of high drainage roadway.Using numerical simulation software COMSOL,according to the actual situation,combined with solid mechanics and structural mechanics module,building subsidence strata movement model,the mined-out area of strata movement change rule,porosity and permeability mined-out area distribution,carried out under the condition of high extraction from the smoke of goaf flow field and gas concentration field simulation,according to the results,numerical simulation has certain reliability.From the perspective of heritage of coal spontaneous combustion and gas explosion comprehensive analysis,to explore and coal goaf spontaneous combustion coupling mechanism and put forward the determination method of disaster,the disaster of 6198 working face and goaf coal spontaneous combustion coupling,it is concluded that: along with the height of mined-out area,increasing the area of the coupling of gas and coal spontaneous combustion disaster danger zone decreases,and the mined-out area in central coupling disaster danger zone is smaller than the area of return air lane side.At the same time,it can be seen that with the increasing height of the goaf,from the middle of the goaf to the side of the return air lane,the coupled disaster risk area is gradually close to the working face.Working face were studied with numerical simulation for different air volume,high pump lane under the condition of different layer and different drainage negative pressure coupled with coal goaf spontaneous combustion disaster change law of available: with the increase working for air,gas and coal spontaneous combustion coupling from the danger zone is gradually increasing the distance of the return air lane,the distance of the distance into the wind lane gradually decreases,and the scope of the coupling of gas and coal spontaneous combustion dangerous area gradually increased;As the distance between high drainage roadway and air return roadway keeps increasing,the distance between gas and coal spontaneous combustion coupling disaster danger area and air return roadway gradually decreases,and the distance between gas and coal spontaneous combustion coupling disaster danger area and air return roadway gradually increases.In the vertical direction of the goaf,with the increasing vertical height of the high drainage roadway,the distance between the danger area of gas and coal spontaneous combustion coupling disaster and the return roadway gradually decreases,and the distance from the inlet roadway gradually increases.In terms of the whole goaf,the area of the hazard area of spontaneous combustion of gas and coal is gradually reduced.As the negative pressure of extraction increases,the distance between the danger area of spontaneous combustion of gas and coal and the return air tunnel decreases gradually,and the distance from the inlet air tunnel increases gradually.Through comprehensive analysis and from the Angle of preventing and controlling the coupling disaster of gas and coal spontaneous combustion in goaf,the reasonable air supply quantity of working face,the best position of high drainage roadway and the reasonable negative pressure of high drainage roadway are determined.The maximum allowable air supply capacity of the working face is 2350m3/min.The optimal position of the high pumping roadway is 20 m away from the coal seam floor and 20 m away from the air return roadway.The reasonable negative pressure of the high pumping roadway is 3kpa.Based on the reasonable spatial location layout and extraction parameters of high pumping roadway determined by numerical simulation,the high pumping roadway is arranged on the spot,and the optimization effect of high roadway parameters is evaluated.According to the actual situation of 6198 working face in Panxi Coal Mine,through field data observation,The distribution law of oxygen concentration,gas concentration and air leakage intensity is analyzed,and the distribution law of floating coal thickness in goaf is calculated.At the same time,combined with the characteristic parameters of coal spontaneous combustion,Based on the superposition of oxygen concentration field,air leakage intensity and floating coal thickness,the risk analysis of goaf is carried out,the "three zones" of spontaneous combustion in goaf are divided,and the dangerous area of spontaneous combustion in goaf is determined.The data of gas concentration and oxygen concentration observed in the field are compared with the numerical simulation,and the reliability of the numerical simulation is verified.The reasonable spatial location arrangement and the setting of extraction parameters ensure that the gas concentration in the fully mechanized top coal caving face and the upper corner is up to the standard,the CO concentration in the high drainage roadway and the upper corner is effectively controlled,and the high efficiency gas extraction effect is realized without causing the spontaneous combustion of coal in the goaf.The coupling disaster of gas and coal spontaneous combustion in goaf is greatly reduced.