多煤层采动层间覆岩破断规律及稳定性控制研究

Study on the Fracture Law and Stability Control of Interlayer Overburden Rock in Multiple Coal Seams Mining

为解决多煤层采动层间覆岩破断复杂、难控制等问题,以神东某多煤层矿井为研究背景,通过理论分析、现场监测与数值模拟相结合的研究手段,分析多煤层开采层间覆岩破断特征及运移规律。首先,基于悬臂梁理论分析计算了多煤层采动下层间覆岩移动量,同时将现场监测数据与理论值进行对比分析;然后,采用3DEC模拟研究了多煤层在不同开采距离下层间覆岩运移及破断特征;最后,提出了煤壁锚索+层间覆岩锚网锚杆强化支护技术。结果表明:可利用多煤层开采层间覆岩运移理论计算层间覆岩裂隙发育高度;多煤层开采过程中易采用下行式开采,上、下煤层间距在20~40 m之间最为合适;多煤层采动过程中层间覆岩移动量呈先增加后降低的趋势,相较于普通支护,煤壁锚索+层间覆岩锚网锚杆强化支护的顶板移近量降低了约65%,取得了良好的支护效果。研究结果为多煤层采动条件下顶板稳定性控制提供了理论依据。

In order to solve the problems of complex and difficult control of fractures at interlayer overburden rock in multiple coal seams mining,taking a coal mine with multiple seams in Shendong as the research background,the fracture characteristics and migration law of interlayer overburden rock in multiple coal seams mining were analyzed by means of theoretical analysis,field monitoring and numerical simulation.Firstly,based on the cantilever beam theory,the movement of overburden rock in multiple seams mining was calculated,and the field monitoring data were compared with the theoretical values.Then,3DEC simulation was used to study the migration and fracture characteristics of overburden rock between multiple coal seams under different mining distances.Finally,the strengthening support technology combining anchor cable in coal wall with anchor net and bolt in interlayer overburden rock was put forward.The results show that the fracture development height of interlayer overburden rock can be calculated by using the migration theory of interlayer overburden rock in multiple coal seams mining.In the process of multiple coal seams mining,it is easy to adopt downward mining,and the spacing between upper and lower coal seams is the most suitable between 20-40 m.In the process of multiple coal seams mining,the movement value of interlayer overburden rock increases first and then decreases.Compared with ordinary support,the roof compared with the ordinary support,the roof displacement of the coal wall anchor cable+interlayer overlying rock anchor net anchor bolt strengthened support is reduced by about 65%,and good support effect is achieved.The research results provide a theoretical basis for roof stability control under multiple coal seams mining conditions.