| Air leakage in goaf is an important cause that leads to spontaneous combustion of the residual coal, and the process of spontaneous combustion results from the coupling effect of seepage flow, gas species diffusion, temperature distribution, etc. Based on the "three-zone" division standard of spontaneous combustion in goaf, the "three-zone" distribution of spontaneous combustion in goaf is simulated adopting the combined measure of critical oxygen concentration and seepage flow rate, which provides theoretical references for prevention of spontaneous combustion in goaf.The coupling feild of seepage flow, air density and temperature distribution in goaf is simulated using the finite element methed. Then the influencing factors, such as different porosity models and different ventilation styles are analysed, which determines the simulation results and the "three-zone" division of spontaneous combustion in goaf. The results show that the width of spontaneous combustion zone is proportional to porosity and air leakage rate in goaf, and that the air leakage rates under the ventilation style W and U are less than that under the ventilation style Y and Z. The spontaneous combustion of residual coal in goaf could be prevented effectively through nitrogen injection to goaf or installation of goaf seal wall.According to the actual situation of serious air leakage on ground in Lianying Coal Mine, the effects of control measures, such as ground filling, nitrogen injeciong to goaf, pressre balance and installation of goaf seal wall are simulated respectively, which influencs the "three zone" division of spontaneous combustion in goaf of fully-mechanized Working Face 201. As result, the critical values of nitrogen injection volume after ground filling, balanced pressue and length of goaf seal wall are proposed, which provides important guidance for the effective and economical prevention of spontaneous combustion of the residual coal in goaf of Working Face 201. |
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