近距离高瓦斯煤层群底抽巷煤与瓦斯共采实践

Coal and gas simultaneous extraction in end-located drainage roadway of high gas coal seam group in close distance

针对近距离煤层群高瓦斯工作面的地质及回采条件,建立采场底板卸压数值分析模型,选取膨胀量和卸压系数两个指标分析了底板煤岩层运移和应力变化特征,指出作用于底板煤岩层应力的急剧增大与减小导致出现卸压膨胀现象,随工作面推进范围扩大,最终膨胀量和卸压系数大小分布呈现马鞍型。为减少底板煤岩体内卸压瓦斯涌入工作面,采用底抽巷治理瓦斯的方案,提出了底抽巷的布置原则。工程试验中,底抽巷顺层钻孔抽采瓦斯纯量及浓度逐渐稳定在最高值7 m^3/min和50%,工作面回风流及尾巷风流瓦斯浓度稳定在0.55%及0.6%以下,实现了煤与瓦斯共采。

In view of the geological and extraction conditions of coal seam group in close dis-tance of high gas working face,the numerical analysis model of pressure relief from stope floor was set up,and the two indexes of swelling capacity and pressure relief coefficient were selected to analyze the coal floor strata movement and the stress variation characteristics. The results showed that the sharp increase and decrease of stress on the coal floor strata result in swelling af-ter pressure relief,with the extended swelling along with the working face advancing.And the fi-nal swelling capacity and pressure relief coefficient distribution present saddle pattern.To reduce the released gas from coal floor strata to rush in working face,the layout principles of end-located drainage roadway was put forward.In engineering practice,the gas emission and its concentra-tion were gradually up to7 m3/min and 50 % from boreholes along seam in end-located drainage roadway,and the gas concentration in air flows of return airway and tail roadway at the working face were stabilized to below 0.5 5 % and 0.6 %,achieving the coal and gas simultaneous extrac-tion.