卸压开采损伤煤岩气体渗透率试验研究

我国煤系地层的煤岩体渗透率普遍较低,直接影响煤矿瓦斯抽采效果。卸压开采使采场围岩受采动应力作用具备了峰后力学行为,其渗透率也大幅度增加,有助于瓦斯的高效抽采。本文基于MTS815.02型电液伺服岩石渗透试验系统,对卸压开采后损伤煤岩的气体渗透率进行了测试。研究表明:(1)卸压损伤煤岩石的渗透率在10-5～10-4 m2之间,较受采动影响前要大107～108倍;(2)卸压过程中,煤样的气体渗透率与围压近似呈线性关系,与岩样呈双曲线关系;(3)卸压损伤煤岩逐渐加围压,气体渗透率近似为线性下降,卸压阶段,其渗透率增加;(4)加卸围压对煤岩的气体渗透率有很大影响。研究结果可为卸压瓦斯高效抽采提供理论依据。

Experimental Study of Gas Permeability of Injured Coal-Rock When Relieving Mining

Penetration rate of coal-bearing strata in China is generally low,which affects directly the gas drainage effect of coal mine.Relieving mining makes the stope rock have post-peak mechanical behavior due to the dynamic stress,so the penetration rate increases dramatically which helps to obtain efficient gas drainage.Gas permeability rate of injured coal-rock after relieving mining was experimentally measured based on an electro-hydraulic servo system.Results show:(1) The gas permeability rate of injured coal-rock is in a range of 10-5~10-4 m2,and is 107~108 times large than the original state;(2) In relieving process,the relation between gas permeability and confining pressure of coal sample is nearly linear;that the relation between gas permeability and rock sample is hyperbola.(3) Gradually increasing confining pressure,the gas penetration rate of injured coal-rock declines approximately linearly,while the penetration rate increases at pressure relief stage;(4) The confining pressure variation has a significant impact on the gas permeability.Above results may provide theoretical evidence for efficient gas drainage.