下保护层开采对上覆巷道围岩稳定性的影响

Study on Influence of Lower Protective Seam Mining on Stability of Roadway Surrounding Rock

为研究下保护层开采对上覆煤巷围岩稳定性的影响,以丁集矿布置于11#煤层上方的1331运输巷为研究对象,对其围岩应力、变形及锚杆轴力变化进行数值模拟研究。结果表明:11#煤层开采对1331运输巷产生了动态影响,根据动态影响程度可将巷道划分为:采动影响稳定区、采动影响剧烈区以及采后卸压稳定区;围岩变形与锚杆轴力变化规律基本一致,最大增速区域均位于工作面前方10 m至后方40 m范围,该范围也是巷道卸压剧烈区范围,围岩应力呈现负指数函数减小趋势,垂直应力与剪应力分别减小20.917 MPa和6.96 MPa,降幅高达44.24%和38.03%;围岩受下保护层采动影响范围约为50 m,顶板受影响程度较大,累计下沉量为165~248 mm。

In order to study the stability influence of upper protective seam mining on overlying roadway surrounding rock,taking 1331 transportation roadway located above 11#coal seam of Dingji Mine as research object,we carry out numerical simulation research for the surrounding rock stress,deformation and changes of bolt axial force.The results showed that the 1331 transportation roadway has a dynamic effect with mining 11# coal seam,according to the dynamic impact,roadway can be divided into three regions：mining influence region,intense mining influence region,and postharvest unloading region;change rule of roadway surrounding rock deformation and bolt axial force is almost the same,the largest growth region is located in the range at the front of working face 10 m to the rear of 40 m,belongs to the range of intense mining influence region.Surrounding rock stress shows a trend of decrease negative exponential function,the vertical stress and shear stress respectively decreased 20.917 MPa and 6.96 MPa,decreasing amplitude is 44.24% and 38.03%.The scope of surrounding rock region affected by upper protective seam mining is about 50 m,the degree of surrounding rock roof influence region is bigger,accumulative settlement is 165 mm to 248 mm.