| Gas of fully mechanized goaf is one of the main parts of the workplace gas emission. Somaster workface goaf gas flow pattern and the implementation of drainage measures inmined-out area is to reduce the face amount of gas emission and the upper corner of the primarymeans of transfinite. Study on the law of gas flow in goaf is necessary for coal mine safety.In this paper, according to the fall rock non-uniform distribution in goaf, the calculationmodel of coefficient of bulk increase according to the "O" type distribution is established andcontinuous function in heterogeneous goaf is given. Under the difference of permeabilitydistribution, permeability size, flow pattern and whether gravitaty factor, leakage seepage, gasmigration regularity and distribution state in the3D goaf are studied and CFD model of moreclose to the actual goaf is realized. Combined with the actual situation of No.N2-706workingface in Daxing coal mine, numerical simulation is conducted by used of optimization model andthe comparative study is made with simulation results and field gas monitoring data, whichverified numerical simulation correctly. According to the N2-706simulation results, there areinversely proportional relationships between drainage flux as well as gas volume concentrationin return airway and gas drainage volume concentration, and the validity of avoided blind andexcessive drainage is validated theoretically. Drainage flow should be controlled at55-65m3/min for No.N2-706working face in Daxing coal mine. |
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