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采场顶板来压极易将采空区内瓦斯压出引发上隅角瓦斯超限甚至瓦斯爆炸。基于岩体的尺寸及时间效应分析了采空区瓦斯宏观流动通道的演化发育规律,应用离散元数值软件计算了顶板来压前后瓦斯宏观流动通道的变化,结合关键层理论研究了基于顶板来压影响及瓦斯宏观流动通道变化的高位抽采钻孔终孔位置、钻场间距及钻孔接续的确定方法及设计技术。结果表明:采空区基本顶载荷作用时间越长,垮断距越大,岩层裂隙越发育;顶板来压及接近来压时瓦斯宏观流动通道最为发育,贯通性最好,其水平裂隙宽度是来压前的3倍,最利于瓦斯抽采。现场应用来压时抽采效率提高约55%,避免了瓦斯超限。
Stope roof to easily pressure the mined area gas pressure out of the top corner of the gas over the limit or even gas explosion. Based on the size and time effect of rock mass, the evolution of macroscopic flow channel in goaf is analyzed. The variation of gas flow channel before and after the roof pressure is calculated by using discrete element numerical software. Based on the theory of key layer, Influence and gas flow channel changes in the macroscopic high-end drilling hole location, spacing and drill hole drilling continue to determine the methods and design techniques. The results show that the longer the top load time is, the bigger the breakage distance is and the more the fractures of rock strata develop. The macroscopically mobile flow channel with the top pressure and near pressure is the most developed with the best penetration and the horizontal crack width is To 3 times before the pressure, the most gas drainage. Field application to pressure extraction efficiency increased by about 55%, to avoid gas overrun.