Research On The Distribution Of Goaf-coal's Gas Parameters And Stress In Liangbei Coal Mine

The 11131 working face of Liangbei coal mine is an isolated island working face.The way of driving along next goaf is adopted to drive its gateway,owing to the larger mining depth,the weak coalbed,the high coal bed gas content and the ways of interval skip-mining.During driving along goaf,how to take comprehensive measures to prevent outburst and whether institute regional preventive measures depend on the distribution of goaf-coal's gas parameters and stress.By applying the methods of theoretical analysis,field test and numerical simulation,this thesis discusses the distribution of stress and gas parameters of 11131 working face during the course of driving along goaf tunnel.1)Before driving along goaf tunnel,this thesis tests gas content along the goaf side and uses the Langmuir formula to get the gas pressure.By analyzing the distribution of this two data,this thesis gets the result that the gas content along the goaf side is less than 6m3/t and the gas pressure is less than 0.5MPa within a 18-meter radius around roadside.After driving along goaf tunnel,this thesis tests parameters of drillings volume,gas desorption index of drillings and Gas Content on site.By analyzing the distribution of these parameters,this thesis gets the result that,within a 20-meter radius around roadside,gas parameters are enlarged with the depth but fail to meet or exceed the critical value of outburst prediction.2)In the goaf,by installing monitoring system of mining stress,this thesis monitors mine-induced stress in real time and analyzes the variation trend which changes along with the time and heading face distance of mine-induced stress.The result shows that the high stress section of the coal body within in a 15-meter radius around the body and the stress in the mechanized caving coal roadway is higher than in the wind roadway.At the same time,this thesis builds a Numerical Simulation Model of 3-D of 11131 isolate working face with FLAC-3D numerical simulation software and studies the distribution and changing laws of mine-induced stress during the course of driving along goaf tunnel.Moreover,by simulating the distribution law of the stress in the coal roadway,this thesis gets the result that the variation trend sensor tallies with numerical simulation results.That is to say,vertical stress increases constantly within a 15-meter radius around roadside.3)By studying on the relationship between the gas parameters and the stress monitoring results of goaf-coal,this thesis gets the results that the gas parameters in coal seam are positively correlation with the stress during mining.4)Based on the distribution law of gas parameters in different position,this thesis analyzes the range of pressure-relief coal seam,the effect of gas drainage and the stability and security of driving along goaf-coal in the different zones of roadside.The result shows that the stress within a 15-meter radius around goaf and the value and distribution of gas parameters accord with Regulations to Prevent Outbursts of Coal and Gas.All these analysis of this thesis reveal that the distribution of goaf-coal's gas parameters and stress.It is useful to provide a theoretical basis for driving along goaf smoothly and offer a reference for similar projects.