保护层开采过程中煤岩损伤与瓦斯渗透性的变化研究

针对煤岩体损伤破坏特征，定义了煤岩体结构损伤变量，建立了相应的弹塑性损伤本构方程，并完成了有限元源程序的二次开发，利用此程序对乌兰煤矿双保护层开采实例进行了计算分析，给出了被保护层损伤程度和渗透性系数的变化规律，计算结果表明：7、8号煤层开采后，被保护2、3号煤层出现张拉损伤，煤层应力显著释放，煤岩体的渗透性急剧提高，有利于瓦斯运移和煤层瓦斯抽采，这与工程实际相吻合。

Research on the coal and rock damage and gas permeability in the protective seams mining

According to the damage characteristics of coal and rock，the damage variable of coal and rock structures was defined，the corresponding elastoplastic damage constitutive equation was established，and the secondary development of the finite element program was completed.The example of Wulan coal mine with double protective seam mining was calculated and analyzed by this new program，and the change laws of damage degree and permeability coefficient in protected coal seams were given.The results show that the tension damage appear in protected coal seams 2 and 3，the stress of coal seams are released clearly，and the permeability of coal seams quickly increases after the protective seams 7 and 8 mined.These results are beneficial for gas migration and extraction in coal seams，which is consistent with engineering practice.