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