Study on air leakage from surface cracks on shallow-buried working face with large mining height
In order to master the air leakage law from surface cracks above the goaf of shallow-buried working face with large mining height,surface cracks investigation,SF6 tracer gas field test,data fitting analysis and other methods were used to analyze the characteristics of surface air leakage,and special air leakage prevention and control measures were developed.The results showed that the surface area of clay layer,which was over 20 m away from the goaf of the working face with large mining height,was easy to develop and form long-term stable opening mode and collapse mode cracks;the air leakage speed of the surface cracks in different regions decreased from high to low as follows:collapse mode crack near the return airway,opening mode crack in the middle of the goaf,collapse mode crack near the inlet airway,and the air leakage speed of different cracks was basically zero after 584 m,539 m and 487 m away from the working face,respectively;through backfilling compaction of surface cracks and grouting plugging of goaf on the return airway side in the underground mine,the concentration of CO at the upper corner was reduced while the concentration of O2 was increased,which effectively inhibited the spontaneous combustion of residual coal in the goaf and reduced the emission of inert gas in the goaf.
shallow-buried coal seamworking face with large mining heightsurface crackSF6 tracer gasspontaneous combustion of residual coal
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