Experimental Study On Gas Migration Rules Of Goaf In Coal Spontaneous Combustion Environment

In recent years,coal spontaneous combustion accidents in the goaf have occurred frequently in China.Gas explosion accidents caused by spontaneous combustion of coal often lead to major casualties and huge economic losses,and the situation of coal mine safety production is becoming more and more severe.However,there are still many vacancies in the study of gas migration under coal spontaneous combustion conditions,which cannot play a guiding role in the actual operation of the coal mine site.Therefore,the thesis focuses on the rules of gas migration when there is a high temperature point in the goaf.In order to study the influence of the presence of high temperature points in the goaf on gas accumulation,the thesis builds a goaf simulation test bench based on a working face of Hegang Xing'an Coal Mine in Heilongjiang Province,and uses a heating module to simulate the spontaneous combustion of coal in the goaf,and the gas in the goaf is replaced by helium.By calculating the height of the caving zone and the fissure zone in the goaf,three layers of measuring points are arranged on the planes with heights of 1 cm,8 cm,and 25 cm,respectively.The experimental schemes of three different wind speeds of 0.2m/s,0.6m/s and 1.0m/s,and three different temperatures of normal temperature,high temperature on the on intake side and high temperature on the wind return side are designed.By comparing the gas distribution in the goaf under the high temperature conditions of the intake side and the wind return side and under normal temperature conditions,the change of gas in the vertical direction,tendency direction and direction is analyzed,and it was concluded that:(1)The presence of high temperature points has the following characteristics on the intake side and the wind return side: the gas concentration near the high temperature point is obviously increased,and the gas concentration contour line is bent at the high temperature point.The gas explosion dangerous area is higher than the normal temperature;under the condition that there is a high temperature point on the intake side and the wind speed is 1.0 m/s,an independent gas explosion dangerous area appears at the high temperature point.As the distance between the vertical direction,the dip direction,and the strike direction from the high temperature point increases,the variation range of the gas concentration decreases.(2)Under the condition that there is a high temperature point on the intake side,as the height in the vertical direction increases,the variation range of the gas explosion dangerous area is reduced at the wind speed is 0.2m/s and 0.6m/s,and the variation range of the gas explosion dangerous area is increased at the wind speed is 1.0m/s.Under the condition that there is a high temperature point on the return air side,as the height in the vertical direction increases,the variation range of the gas explosion dangerous area is reduced at each wind speed.(3)Under the condition that there is a high temperature point on the intake side and the wind return side,as the wind speed increases,the area of the gas explosion dangerous area increases in both the strike and the dip direction of goaf.Through the analysis of similar experiments,the law of gas migration when there is a high temperature point in the goaf is obtained,the thesis provides a necessary experimental basis for the prevention and control of gas explosion in coal gas spontaneous combustion in high gas and easy spontaneous combustion coal seam,and has certain reference value in actual production.