沿空留巷采场围岩力学特征数值模拟研究

为揭示沿空留巷采场上覆围岩的力学特征,以谢桥煤矿12418工作面地质和开采技术条件为背景,采用数值模拟进行了计算和分析。研究表明:工作面上覆围岩存在应力壳(高应力束组成)和老顶岩层承载结构,共同承担、传递和转移上覆岩体的荷载,工作面位于两者保护的低应力区内。工作面围岩破坏场发育在高应力集中区下的卸压区内,而破坏造成的离层区域位移量最大。沿空留巷的刚性充填体导致其自身和覆岩处于高应力状态,形成完整未破坏区域,降低了采空区上方破坏区的高度和范围,使本工作面采空区上方破坏区不能与临近破坏区贯通,瓦斯得不到有效释放和卸压。在倾向方向,工作面中部垂直位移大于上部和下部,对充填体产生向巷道内的水平推力,充填体水平位移较大,不利于巷道围岩稳定性控制。因此,合理控制充填体的强度和刚度是沿空留巷开采取得最佳效果的关键。

Numerical Simulation on Mechanical Characteristics of Surrounding Rock of Gob-Side Entry Retaining

This paper revealed the mechanical characteristics of gob-side entry retaining overlying surrounding rock according to the geological conditions and mining technical conditions of working face 12418 in Xieqiao coal mine by using numerical simulation. The study shows that there were the stress shell and main roof existed in the overlying strata above the working face, which bore, transfered the overburden load together, and the working face was located in the low stress area protected by the stress shell and main roof. The destroyed field was located in the distressed zone under the stress concentration area, and the displacement was the biggest in the abscission zone. The filling and overlying strata were always situated in the high stress state for the rigid backfill in the environment of the gob-side entry retaining, and the complete undamaged area was formed and the height and scope of failure zone above the goaf was decreased, the failure zone above the goaf mutually was independent to the adjacent goaf, so the gas could not be released effectively. The vertical displacement in the middle of working face was bigger than that of the upper and lower along the dip, which caused horizontal thrust to roadway interior, and the backfill had big horizontal displacement, which was inimical to the control of surrounding rock stability. So the reasonable strength and stiffness of backfill was the key for the best results of gob-side entry mining.