采空区下大断面开切眼交替掘进围岩稳定性分析

Stability Analysis of Surrounding Rock in Alternate Excavation of Large-Section Open-Off Cut Under Goaf

为实现近距离采空区下大断面开切眼交替掘进一次成巷技术的安全高效施工,以任楼煤矿的Ⅱ7_322工作面和Ⅱ8_(2)24工作面的地质条件和开采条件为研究背景,采用相似模拟、理论分析和现场实测相结合的研究方法,对近距离采空区下开切眼过程中,围岩移动变形和应力演化对围岩稳定性的影响进行了研究。结果表明:采空区底板岩层最大破坏深度为4.56 m,Ⅱ8_(2)24开切眼顶板上方7.64 m处未遭到破坏部分细砂岩工程分级为差的Ⅳ级岩体,粉砂岩工程分级为中等的Ⅲ级岩体;采空区底板所受最大应力低于相似材料模拟试验的材料强度,采空区开采对Ⅱ8_(2)24开切眼顶板围岩稳定性影响较小;大断面开切眼交替掘进一次成巷会造成围岩应力的二次扰动,开切眼帮部围岩垂直应力波动最为剧烈,两帮的表面位移收敛大于顶底板,应着重注意对两帮的支护工作。

In order to realize the safe and efficient construction of one-time tunneling technology for large-section open-off cut under close-distance goaf,taking the geological conditions and mining conditions of Ⅱ7_(3)22 working face and Ⅱ8_(2)24 working face of Renlou Coal Mine as the research background,the similar simulation,theoretical analysis and field measurement were used,the influence of surrounding rock movement deformation and stress evolution on the stability of surrounding rock in the process of open-off cut under close-distance goaf was studied.The results show that the maximum failure depth of the floor strata in the goaf is 4.56 m.The fine sandstone engineering of the undamaged part of 7.64 m above the roof of the Ⅱ8_(2)24 openoff cut is classified as poor grade IV rock mass,and the engineering classification of siltstone is medium grade Ⅱ rock mass.The maximum stress of the floor of the goaf is lower than the material strength of the similar material simulation experiment,the mining of the goaf has little effect on the stability of the roof surrounding rock of the Ⅱ8_(2)24 open-off cut.The alternate excavation of large-section open-off cut will cause the secondary disturbance of surrounding rock stress.The vertical stress fluctuation of surrounding rock in the side of open-off cut is the most severe,and the surface displacement convergence of the two sides is greater than that of the roof and floor.Attention should be paid to the support work of the two sides.