低透气煤层预裂瓦斯运移数值模拟及抽采试验

针对高瓦斯低透气性煤层瓦斯抽采难问题，利用数值模拟软件RFPA^2D—Flow再现了采取煤层深孔爆破预裂后，瓦斯在煤层及爆生裂隙中的流动规律。研究结果表明，预裂圈内煤和岩石的孔隙率大大提高，煤层透气性显著增加，但当裂隙圈之间不相交时，瓦斯同样很难在完整的低透气性煤体中运移，因此只有当抽采瓦斯钻孔处在裂隙圈中才能高效抽采瓦斯。现场试验证实，低透气性煤层预裂后，有效导通裂隙增加，布置在裂隙圈内抽采瓦斯钻孔可以获得高效抽采瓦斯效果，从而降低煤与瓦斯突出危险性。

Numerical Simulation of Gas Migration in Pre-splitted Coal Seam with Low Permeability and Experiment of Gas Extraction

The object of the study is difficult gas extraction in coal seam with high gas and low permeability. The law of gas flow in the coal body and cracks caused by pre-splitting blasting in long-hole was simulated by use of software RFPA20-Flow. The results showed that porosity rate of the coal body and rock mass and the permeability in pre-splitting zones increased significantly. However, gas migration in not splitted part of the coal body with low permiability is still very difficult, when pre-splitting zones don＇t intersect each other. Consequently, only when boreholes of gas extraction are distributed in presplitting zones, can the gas in the coal seam be efficiently extracted. Experiments in-situ showed that number of cracks effectively interconnected in coal seams with low permeability increase after pre-splitting blasting, and the threat level of coal and gas outburst is consequently reduced, as a result of efficient extraction of gas from borholes distributed in pre-splitting zones.