Study On The Width Of The Pressure Relief Zone And Gas Discharge Zone Of The Coal Seam In The Goaf Of Xintun Mine

Coal,as one of the main energy sources in China,will not change in the future a period of time.The environment in which coal is located is relatively complex,which leads to accidents during the mining process,which seriously affects the safe and efficient production of coal mining enterprises.The danger of coal and gas outburst increases with the increase of the mining depth,and it often occurs in the working face of the coal roadway.Corresponding measures must be taken in the design of coal lanes,uncovering coal in Shimen and digging up and down the mountain.Coal and gas outburst are closely related to in-situ stress and gas action.In the layout of the lower section of the mine,the design and driving of the shaft and roadway,outburst prevention and control work should be carried out in two aspects of in-situ stress and coal seam gas occurrence.In this paper,by means of theoretical analysis,numerical simulation and field test,relevant studies are carried out on the pressure relief width of coal body around the goaf and the gas discharge width of coal seam.(1)The Universal Distinct Element Code numerical simulation software was used to study the 14271 goaf trend and the width of the inclined pressure relief zone.The results show that the range of pressure relief zone of coal body is 5m ～ 6m,the range of stress concentration zone is 6m ～ 25 m,and the range of greater than 25 m is the original rock stress zone.In the inclination model,the range of pressure relief zone of the coal along the upper trough is 5m ～ 6m,the range of stress concentration zone is 6m ～ 25 m,and the original rock stress zone is greater than 25m;the range of the pressure relief zone of the coal along the lower channel is 5m ～ 6m,the range of stress concentration zone is 6m ～ 20 m,and the original rock stress zone is greater than 20 m.For this simulation,the numerical simulation results of the range of pressure relief zone around the coal body in the goaf indicate that the width of the pressure relief zone around the goaf is basically the same.Field test results show that the width of the pressure relief belt is 8m.The width of the pressure relief zone in the goaf is larger than the numerical simulation results.Because coal rock itself has rheological properties,after mining for a period of time,concentrated stress moves to the deep part of the coal body,and the width of the pressure relief zone increases.Finally,the width of the pressure relief belt is 8m.(2)Use COMSOL Multiphysics numerical simulation software to study the width of coal gas discharge zone.The results show that the limit gas discharge width is about18 m ～ 20 m.As the coal wall distance increases,the gas pressure gradually increases to the original gas pressure and remains unchanged.At the same distance from the coal wall,as the time increases,the gas pressure gradually decreases and approaches a stable value.The gas pressure gradient gradually decreases with time.The limit gas discharge width increases with the increase of original gas pressure and the initial permeability of coal.Combined with the field test,the results show that the final gas emission width is18 m.