Research On The Influence Of Buried Pipe Extraction On Spontaneous Combustion In Goaf Of Baode Coal Mine

With the development of coal mining in depth,the problems of gas exceeding the limit and coal spontaneous combustion are very prominent,and become two major hazards restricting the safety of underground production.This paper combines the actual situation of the comprehensive mechanized caving coal mining technology in81307 working face of Baode Coal Mine,and uses the basic theories of coal spontaneous combustion process and influencing factors,porous medium theory,gas seepage and diffusion law in goaf,and seepage control equation.Through the methods of test analysis,numerical simulation and field measurement,to study the spontaneous combustion law of goaf in the presence or absence of buried pipe extraction and different depths of the extraction pipe.The results show that:?1?Through collecting coal samples from 81307 working face on site,the low temperature oxidation test of coal spontaneous combustion was carried out.Under different oxygen supply conditions,the product of coal spontaneous combustion process was optimized,and the regularity of production of CO and C2H4 was analyzed.The lower limit of oxygen concentration which can maintain spontaneous combustion in coal seam was determined to be 8%,which can be used as a reference for dividing the"three zones"of spontaneous combustion in goaf.?2?According to the characteristics of the overlying strata and the general law of the caving of the goaf,the mathematical model of gas seepage and diffusion in the goaf is constructed by the equations of mass,momentum,energy and component transport,and the related parameters such as porosity,viscous resistance coefficient and inertia resistance coefficient are calculated.The ANSYS FLUENT software was used to simulate the variation of the spontaneous combustion zone in the goaf under the four conditions of no extraction,buried depth 20m,buried depth 60m and buried depth100m.?3?By arranging measuring points on site,collecting gas samples and temperature,and analyzing the variation rule of O₂ and temperature,it is concluded that the"three zones"of spontaneous combustion in goaf are less than 105 m as heat sink zone,105²70 m as oxidation zone and 270 m as asphyxiation zone under the condition of combined tunnel extraction.Compared with the numerical simulation results,the error is within the allowable range,which verifies the accuracy of the simulation results.The main research contents of this paper provide a reference basis for fully mechanized caving face with coal and gas coexisting and adopting combined tunnel buried pipe extraction method;at the same time,it has certain application value for guaranteeing the effect of goaf extraction,taking into account the prevention and control of residual coal spontaneous combustion,and ensuring the safe and orderly underground operation.Figure[29]Table[10]Reference[63]...