近距离倾斜煤层下行开采覆岩裂隙发育特征及采空区瓦斯运移规律

Development Characteristics of Overburden Fracture and Gas Migration Law of Goaf after Downmining of Close Inclined Coal Seam

近距离倾斜煤层开采后覆岩裂隙发育呈不对称特征,引起采空区瓦斯运移分布规律产生变化。采用UDEC等数值模拟软件,对上下煤层不同推进距离下覆岩裂隙发育规律及夹矸破碎特征进行分析,研究了瓦斯及氧气在贯通采空区内运移分布规律。结果表明:近距离倾斜煤层下行开采后右侧覆岩裂隙发育高度大于左侧,夹矸破碎后使得上下煤层采空区贯通,得到压实、再压实等不同分区气体运移空间,根据近距离倾斜煤层优化后三维“O”形圈模型,模拟得到瓦斯浓度在采空区靠近回风巷上隅角处达到13.2%,在距工作面70~140 m内瓦斯浓度增大15%。

The development of overburden fractures is asymmetrical after the mining of close inclined coal seam,which causes the change of gas migration and distribution law in goaf.Numerical simulation software,such as UDEC,was used to analyze the development law of overlying fractures and the characteristics of gangue fragmentation under different advancing distances of upper and lower coal seams,and the migration and distribution law of gas and oxygen in goaf were studied.The results showed that:the development height of overburden fractures on the right side is higher than that on the left side after the downmining of the close inclined coal seam.After gangue fragmentation,the goaf of the upper and lower coal seams is connected,and gas migration spaces of different zones such as compaction,re-compaction and so on are obtained.According to the 3D"O"ring model optimized by the close inclined coal seam,it is simulated that the gas in the goaf near the return air roadway reaches 13.2%.In the range of 70~140 m away from the working face,the gas concentration increases by 15%.