构造煤承压过程瓦斯渗透特性实验研究

构造煤具有瓦斯含量高、渗透率低等特征，是瓦斯抽采和灾害预防的难点。在采用“二次成型”法制取原煤样试件的基础上使用自行设计的“三轴应力瓦斯渗透性模拟实验装置”通过“应力-渗透性”实验，针对构造煤原煤试件不同瓦斯压力条件下的应力加、卸载过程的瓦斯渗透规律进行了研究。实验结果表明:加载阶段，随着加载应力的增大渗透率降低，初期阶段降幅最为急剧，围压升到3 MPa时，渗透率均下降近65%；卸载阶段渗透率随着应力的减小而增大，围压完全卸载后渗透率只恢复到初始值的25%；同样的应力条件下，煤基质收缩对构造煤的影响作用大于有效应力的增加，渗透率随着其内部瓦斯压力的降低而增大。实验结果可为构造煤“卸压增透”效果最佳化提供参考，进一步完善低渗透率煤层的瓦斯抽采理论及方法体系。

Experimental study on gas permeation characteristics of tectonic coal during the pressure loading and unloading process

The tectonic coal has the characteristics of high gas content and low permeability, which is difficult for gas drainage and disaster prevention. On the basis of preparing raw coal sample specimens with the "secondary molding" method, the gas permeation regularity of raw tectonic coal sample specimens during the stress loading and unloading process under different gas pressure conditions were studied through the "stress-permeability" experiments by using the self-designed "three axis stress gas permeability simulation experiment device". The results showed that in the loading stage, the permeability decreased with the increase of loading stress, and the decreasing amplitude was the most sharp in the early stage. The permeability decreased by nearly 65% when the confining pressure increased to 3 MPa. In the unloading stage, the permeability increased with the decrease of stress, and the permeability was only 25% of the initial value when the confining pressure was totally unloaded. Under the same stress conditions, the effect of coal matrix shrinkage on the tectonic coal was greater than that by the increase of effective stress, the permeability increased with the decrease of internal gas pressure. The experimental results can provide reference for the optimization of the "pressure relief and permeability enhancement" effect of tectonic coal, and further improve the theory and method system of gas drainage in low permeability coal seam.