Technology of split-layer roof cutting and pressure relief for roadway protection in contiguous seams

Upper coal mining will have mining influence on lower coal when mining in contiguous seams, resulting in the deformation of the surrounding rock of the mining roadway near the lower layer coal. The technology of split-layer roof cutting and pressure relief for roadway protection in contiguous seams was put forward. The technical principle of split-layer roof cutting and pressure relief for roadway protection was analyzed, and the calculation formula of split-layer roof cutting height in contiguous seams was deduced. The key parameters of split-layer roof cutting were given, and the effect of roof cutting and pressure relief for roadway protection was studied. The results show that the length of cantilever beam can be shortened by adjusting the fracture position of split-layer roof cutting actively, and the energy transfer of backward rock is reduced due to the buffering action of goaf and intercalation, which effectively protects the stability of surrounding rock of lower roadway. In addition, the influence of caved refuse of roof on the filling effect of the local level airside and the lower level airside and the caved rock between layers should be considered in the determination of the height of split-layer roof cutting. The field industrial test shows that the floor heave of dynamic pressure roadway decreases from 3.0 m to about 0.5 m after split-layer roof cutting, with a decrease of 83%.