下保护层开采上覆煤岩位移传导效应特征研究

Characters Study on Displacement Conduction Effect in Overlying Coal and Rock During Lower Protective Seam Mining

为深入研究下保护层开采过程中上覆煤岩位移传导效应的时空演化机制,基于煤岩位移传导理论,从时间和空间角度分析了煤岩状态、地应力及渗透性在位移传导相对滞后和传导强度相对减弱影响下的变化过程,确定了被保护层瓦斯抽采的最佳布孔区域和最佳抽采时机。同时结合工程实践,在被保护层中选用煤岩位移传导效应的响应参数进行考察,结果表明:沿保护层工作面推进方向,被保护层瓦斯压力表现为上升-稳定-缓慢下降-快速下降-稳定-上升-稳定的变化过程,类似于马鞍状;被保护层瓦斯流量和煤层变形率均呈现稳定-下降-缓慢上升-快速上升-稳定-下降-稳定的变过程,类似于"S"型波动;下保护层开采有力促进被保护层应力释放和瓦斯运移。

In order to further study the displacement conduction effect about spatiotemporal evolution mechanism in overlying coal and rock during lower protective seam mining,the paper analyzed the changing process of coal and rock state,stress and permeability that were influenced by relatively backward displacement conduction and relatively weakened strength in the aspects of time and space,which based on theory of displacement conduction in overlying coal and rock. So,it confirmed the best regional hole arrangement and the best occasion for gas extraction in the protected coal seam. Combing with engineering practice at the same time,the response parameters for displacement conduction effect were used to investigate in the protected coal seam; the results showed that the gas pressure of protected coal seam changed in rising- stability- falling slowly- falling quickly- stability- rising- stability along the direction of lower protective seam mining,which was similar with shape of saddle. The gas flow and deformation rate of protected coal seam changed in stability- falling- rising slowly- rising quickly- stability- falling- stability along the direction of lower protective seam mining,which was similar with shape of ＂ S＂. The lower protective seam mining was strong in stress relief and gas delivery in protected coal seam.