The Mechanism of Mining-Induced Stress Evolution and Ground Pressure Control at Irregular Working Faces in Inclined Seams

摘要

Surrounding rock control is problematic at irregular fully-mechanized working faces of inclined seams. This study investigated the evolution of mining-induced stress at a variable-length working face under different coal seam inclination angles by using FLAC3D software to establish an experimental model based on the occurrence conditions of the inclined seam and the layout of fully-mechanized working face in the western district of Pan'er mine in China. Analysis of the simulation data was used to determine the stress evolution of working face in the strike and dip directions under different dip angle conditions and reveal the relationship between mining stress evolution and coal seam inclination. Comparative analysis of the formation and evolution of mining-induced stress before and after the roadway connection was used to determine the mechanisms behind mining-induced stress evolution in the short face to long face connection process and to reveal asymmetrical differences in the mining-induced stress evolution of the upper, middle and lower parts of the coal seam along the dip direction. Based on the relationship between supports and surrounding rock, the structure of hydraulic powered supports, the entry arrangement and supporting characteristics, control methods to ensure the stability of surrounding rock are proposed such as a metal mesh above hydraulic powered supports and reinforcement at the junction. These measures are effective for preventing partial roof fall and rib spalling, loss of support stability and stress concentration at connecting entry and for achieving safe and efficient mining of irregular working faces in thick inclined seams.