Asymmetric failure characteristics and control technology of gently inclined coal seam and crushing roof roadway

Using the 3DEC-BBM discrete element numerical simulation method, this study analyzed the distribution of fractures, deformation, and failure characteristics of the surrounding rock of 1507 transportation roadway in Tianshuibao Coal Mine. It compared the responses of the surrounding rock under different coal seam dip angles and roof conditions. A segmented control scheme involving "optimized excavation methods + enhanced support for fractured roof + reinforcement support for roadway sides" was proposed and implemented. The results indicate that the roadway failure is primarily characterized by shear slip and separation at both sides, with a maximum failure depth of 3.2 m. The presence of a coal streak in the roof increased roof subsidence by 48.36%. When the coal seam dip angle exceeded 10°, deformation of the high side increased significantly, showing obvious asymmetry. After reinforcement support, the maximum convergence of the two sides was reduced to 160 mm, and the roof-to-floor convergence was about 100 mm, effectively controlling roadway deformation. The main causes of asymmetric failure are variations in rock properties, the dip angle effect, and insufficient original support. The proposed segmented control technology significantly enhances roadway stability and is applicable to support design in roadways under similar geological conditions.