Abstract:
In response to the surrounding rock instability in lower-seam roadways caused by superimposed multiple mining disturbances during downward mining of close distance coal seams, this study focuses on the gas management roadway in the No. 8 coal seam of Shanxi Hengyuan Coal Mine. Using FLAC
3D numerical simulation, the distribution of deviatoric stress and the evolution of the plastic zone in the lower coal seam during the extraction of the overlying No. 6 coal seam were analyzed. The results show that mining activities in the upper seam cause the peak deviatoric stress in the floor to decrease with increasing distance from the goaf floor. The mining-induced stress can be directly transferred to the lower coal seam, resulting in an asymmetric and abnormal stress environment around the roadway. The superposition of residual stress from the 060302 working face, roadway excavation stress, and mining-induced dynamic pressure from the 060303 working face exacerbates the asymmetric expansion and eventual connection of the plastic zone, significantly reducing roadway stability. Based on these findings, a combined active and passive support system of "high pre-tension anchor cable trusses + single hydraulic props + steel beams" was proposed. Engineering applications demonstrate that this approach effectively suppresses roof separation and rib deformation, addresses issues such as roof falls and anchor bolt failures, and significantly enhances roadway stability.