Study on migration instability characteristics and mine pressure control of roof overburden rock in thin coal seams mining.

In the Guxu mining area, the mining of thin coal seams is complicated by the unknown migration structure of the roof overburden and severe mine pressure. Based on this, taking the 1599 working face as the research background, and using a method that combines theory with simulation, starting from the structural fracture of roof overburden rock in thin coal seams, the roof failure characteristics during the mining process are studied, and the roof caving shape and stress distribution characteristics under the influence of mining speed are studied is explored. The research results show that a cantilever beam with a short length forms in the overburden rock of the soft bedrock roof during thin coal seams mining. The roof strata 2,5 and 10 of the 1599 working face control the local overburden activity respectively. After fracture, the pressure increases obviously, and with the collapse of the upper strata controlled by it, the pressure phenomenon occurs in the working face. For thin coal seams, the peak value of supporting stress is slightly smaller than that of medium-thick coal seams, but the peak point of supporting stress is closer to the coal wall. When the advancing speed increases, the length of the cantilever beam will increase, the maximum stress concentration factor and the advance influence range will also increase, but the peak value will shift to the deep part. Therefore, the rapid advance will make the front high stress area away from the working face, and the slow advance will cause the roof overburden pressure relief time to become longer. For the composite bearing layer structure, the acceleration of the advancing speed will cause the bearing performance of the lower bearing layer to be weakened and the bearing performance of the upper bearing layer to be enhanced.