Movement and deformation characteristics of overlying stratum in paste composite filling stope

Paste composite filling mining is one of the effective ways to realize green mining. In order to study the movement and deformation characteristics of overlying stratum in paste composite filling stope, taking the test mine as the engineering background, a mechanical model of movement and deformation of roof rock beam in paste composite filling mining was established by combining theoretical analysis, physical simulation and numerical simulation. The movement and deformation laws of main roof, sub-key stratum and main key stratum in the process of working face advancing under the conditions of multiple factors (mining height, filling ratio and buried depth) were analyzed. The results show that the displacement contour of overlying stratum is inverted trapezoid in the process of advancing working face which is unfilling or filling 2/3. The subsidence of stratum near the coal seam is larger, and the subsidence of stratum with higher distance from the coal seam is smaller, and the maximum subsidence point of overlying rock appears near the side of the open-off cut. With the increase of mining height, the range of overlying rock caving zone becomes larger, and the maximum subsidence value gradually increases. When the paste filling ratio of the working face increases, the collapse range of the roof decreases, the overall compression of the collapsed rock decreases, and the effect of control on the movement and deformation of the overlying rock is obvious. The subsidence of overlying stratum increases with the increase of buried depth of working face, but it does not change much. The deflection value of the roof rock beam changes slowly at both ends of the propulsion due to the support of the coal wall. The closer to the middle, the greater the change. The results of this study can provide an important reference for the control of the roof stability and surface subsidence of the paste composite filling mining.