Mechanical Mechanism of Working Face Roof Under Variable Coefficient of Subgrade Reaction in Filling Mining

To provide theoretical basis for guiding filling mining and roof control measures of working face, based on the engineering background of wind-blown sand paste filling mining in Yuyang Coal Mine, the foundation bed coefficient of the broken coal body area in front of the working face is considered to be an unsteady constant. At the same time, considering the changing characteristics of the foundation bed coefficient of backfill body with the age, the elastic foundation beam model with variable foundation bed coefficient of roof of working face is established. It is calculated by finite difference method and the distribution laws of roof deformation and bending moment were analyzed. In addition, the prevention and control measures to cope with the failure of the roof caving were proposed. The results show that the maximum deflection of roof is above the area waiting for filling, and the minimum one is above roof-control area, and it decreased with the increase of the variable coefficient of subgrade reaction. It was easy to cause bending shear failure of roof because bending moment was varied violently in the range of roof-control area and waiting for filling area.