Research On Influencing Factors And Application Of Electrothermal High Temperature Field In Outburst Coal Seam Closed Area

Most mines in my country are high gas mines,and coal and gas outburst accidents have always been one of the main controlling factors that inhibit the safe and efficient mining of coal mines in my country.At present,gas drainage is a fundamental measure to prevent coal mine outburst accidents.However,due to the extremely complex geological structure in my country,combined with the characteristics of deep coal seams such as high ground stress and gas pressure,and poor coal seam permeability,the effect of gas drainage is not ideal,and it is widespread.Problems such as low drainage rate and difficulty in drainage.In response to the above situation,this paper proposes a new technology that uses electric heating to promote coal seam gas desorption,discharges it into the closed roadway area through drilling,and finally uses a drainage pipeline to extract the gas from the roadway.Using a combination of theoretical analysis,experimental research,and numerical simulation,based on the elasticity of porous media,seepage mechanics,thermodynamics and other related theories,a mathematical model of the electric heating high temperature field in the confined area of the outburst coal seam is established.Taking the K15 coal seam of Songhe Coal Mine in Guizhou as the engineering background,COMSOL Multiphysics5.5 software was selected to systematically study the influencing factors of the electric heating high temperature field in the confined area of the outburst coal seam.The main research results are as follows:(1)According to the characteristics of the fracture-pore structure of coal,the dynamic control equations of porosity and permeability considering the temperature effect are derived,and on this basis,the control equations of coal stress field,gas seepage field and temperature field are established.Combining the above equations,a multi-field coupled mathematical model of electrothermal high temperature field including coal deformation,gas seepage and temperature effects is obtained.(2)Through experimental analysis,as the heating temperature increases,the temperature rise rate per unit time at the location of the temperature sensor increases;after the temperature in the coal sample reaches a stable state,the temperature of the coal sample at the temperature sensor location will fluctuate slightly or remain constant,Until the heating is stopped;as the heating temperature increases,the maximum heating temperature after the temperature of the coal sample reaches a stability will increase,and the heating radius will increase accordingly.(3)With the Songhe Coal Mine in Guizhou Province as the engineering background,the established heat-fluid-solid mathematical model was used to carry out a numerical simulation study of gas drainage in a closed mining face under an electric heating high temperature field.The results show that under the action of the drainage holes and heating holes,the gas pressure in the coal seam continues to decrease with the increase of the drainage time,and the longer the time,the lower the residual gas pressure in the coal seam.The gas pressure of the coal seam is affected by the extraction holes and heating holes,which expands outward along the extraction holes and heating holes,and gradually extends to the entire coal seam.