Preparatory process of floor shock caused by unloading effect during excavation of coal roadway

Through numerical simulation and similar simulation methods, the stress distribution and deformation laws of floor caused by coal seam excavation are studied, and the preparatory process of floor shock is revealed. The results show that lots of conditions such as mining depth, roof condition and roadway drifting and layout ways have great influence on floor shock. Under the influence of thick hard roof, the mining of working face will increase the stress of adjacent working face. In thick coal seam, roadway is cut along roof of the coal seam, so the floor is coal seam left. After roadway is cut, at certain extent, the horizontal stress increases and the vertical stress decreases in the floor, and this increases the stress conditions for buckling failure in seam. During unloading of the roadway excavation, because the floor is not supported and the vertical displacement increases, the plastic zone of floor is bigger than the two sides, and tensile failure appears in the floor obviously, and this is the sally port of floor shock. The conclusions of the study provide theoretical foundation and ways for researching the mechanism and prevention methods of rock burst.