Prediction of spontaneous combustion danger zone in overlying shallow and close goaf during mining processes
To reveal the influence law of surface fracture development on the spontaneous combustion of residual coal in the overlying goaf during the mining of short-range coal seams,three-dimensional geometric models and mathematical model of goaf are established,including flow field flow equation and low-temperature oxidation model,with Sujiagou Coal Mine as the research background.Based on the above models,the oxygen concentration distribution in the overlying goaf during the advancement of the working face of the lower coal seam is simulated by Fluent software.And the distribution pattern of oxygen and airflow fields under the dynamic development of fractures in the overlying goaf was obtained.Furthermore,the risk area of spontaneous combustion in the upper goaf is determined based on the standard for the classification of spontaneous combustion hazard zones.The research results show that the number of cracks connecting the surface and goaf increases with the advance of the working face and the oxidation temperature rise zone in the goaf is concentrated in the range of 0-20 m behind the working face.Besides,the oxidation zones in depth goaf are distributed near the new and old fractures-the air inlet side is close to the surface and the air return side is close to the bottom of the fractures.When the working face advances 120 m,three through cracks are generated.In this case,the oxidation zone is the most widely distributed and accounts for the largest proportion of the goaf,which lead to the greatest risk of spontaneous combustion.The intersection of the distribution cloud map of the oxidation zone and airflow field is determined as the spontaneous combustion danger area,which is the key protection area in the process of coal mining,and the horizontal distance between the risk zone and working face is 97.5 m.
safety engineeringclose coal seamsgoaf spontaneous combustionnumerical simulationhazardous area prediction
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NSTL
万方数据
维普
