Research on Stoping Roadway Layout and Support Technology Process of Lower Coal Seams

In small spacing coal seam mining, the support stability of lower roadways under the disturbance of upper coal seams is a key problem that restricts the mine safety production. Aiming at the technical difficult problem of large difficulty in support caused by the small spacing between coal seams in Guzhuang Coal Mine, a combination method of theoretical analysis and numerical simulation is adopted to study the influence of the internal displacement in the lower stoping roadways on the surrounding rock stress and plastic zone. Four kinds of layer spacing working conditions are divided: <2 m, 2-5.5 m, 5.5-13.5 m, and >13.5 m, differentiated support schemes are proposed: "grouting+anchor mesh+shed" is adopted for layer spacing <2 m, "anchor mesh+shed" is adopted for layer spacing between 2-5.5 m, and "anchor rod (cable)+metal mesh" (parameter differentiation) is adopted for layer spacing above 5.5 m. On-site tests are carried out in the 1150 track roadway. The results show that when the lower roadway internal displacement is 30 m, it is in the pressure relief zone, with stress peak values of 0.75 MPa and 0.82 MPa on the roof and floor respectively, and the plastic zone is not penetrated; The on-site monitoring indicates that the deformations of the roadway surrounding rock are all controllable under various working conditions, with the maximum deformation amount of 162 mm and 137 mm for the roof, floor, and two sides when the layer spacing is <2 m. This research determines that the reasonable internal displacement is 30 m, and the proposed scheme meets the safety production requirements and can provide technical reference for roadway support with similar conditions.