Layout and combined support technology of alternate exterior stagger arrang- ement roadway and adjacent roadways in inclined and medium-thick coal seam

Research is conducted on the gob-side gateroad driving and support technology in an inclined and medium- thick coal seam. By constructing a mechanical model,the fracture position and fracture form of the main roof are deter- mined according to the maximum bending moment of the main roof. It is calculated that the main top reaches the maximum bending moment at a distance of 17. 57 m from the coal pillar and the maximum bending moment is 23. 02 MN·m,which further determines that the fracture position is located on the side of the solid coal. Combined with the “inside and outside stress field” theory,the calculated “internal stress field” range is 15. 89 m. Considering the space relationship of the roadway,the horizontal offset of the narrow coal pillar is determined to be 7. 37 m and the vertical offset is 2. 40 m. The above experimental analysis determines that the experimental range of the section coal pillars is 7-12 m. The stress field and plastic zone distribution of different coal pillar sizes are calculated and analyzed by the FLAC3D numerical simulation software and the dimensional stability of different coal pillars is studied and veri- fied under the two stages of excavation and mining. The reasonable width of the narrow coal pillar is finally determined to be 8 m. Based on the spatial structure characteristics of adjacent roadways in split-level roadway arrangement,the combined support technology is proposed and its technical characteristics are analyzed theoretically. The broken zone theory is used to determine the joint support parameters of the adjacent roadway and the FLAC3D numerical simulation software is used to simulate the combined support scheme and the original support plan. The effects of the two support schemes under different stages are verified from the aspects of support stress field,plastic zone distribution and relative deformation rate of surrounding rock. The final result shows that the combined support scheme is more conducive to the deformation control of the surrounding rock of the roadway.