2种典型煤样承压过程瓦斯渗透特性试验

Experimental study on gas seepage characteristics of two typical coal samples during pressure loading and unloading processes

为探索同一应力加卸载路径下2种典型煤样(原生结构煤及构造煤)的瓦斯渗透规律,用3轴应力瓦斯渗流模拟装置,对2种原煤试件不同瓦斯压力承压时的瓦斯渗透特性进行试验研究。结果表明,加载阶段,随着加载应力的增大,2种煤样的渗透率均呈下降趋势,且初期降幅最急剧,当围压从0升到3 MPa时,2种煤样的渗透率分别下降64%和70%;卸载阶段,渗透率随着应力的减小而增大,围压完全卸载后,2种煤体的渗透率分别恢复到初始值的25%和50%;在同样的应力条件下,有效应力的增加对原生结构煤的影响作用大于煤基质收缩,渗透率随着瓦斯压力的增加而增大,而对构造煤则相反,渗透率随着瓦斯压力的降低而增大。

In order to explore the gas permeability law of two typical coal samples（primary structure coal and the structure coal） under the same stressloading and unloading path, experiments were carried out using a three axis stress gas permeability simulation experiment device. The results show that the permeability of the two samples decreases with the increase in the loading stress in the loading phase, and the decreasing amplitude is the most dramatical in the early stage, that their permeability decreases by nearly sixty four and seventy percent respectively when the confining pressure increase from 0 to 3MPa, that in the unloading phase, the permeability increases with the decrease in stress, and the permeability is only twenty five and fifty percent of the initial value respectively, and that under the same stress condition, for the primary structure coal, the effect of the increase in effective stress is greater than that of the coal matrix shrinkage, and the permeability increases with the decrease in the gas pressure, and that for tectonic coal, the permeability increases with the decrease in the gas pressure.