Specifics of the influence of secondary support deformation characteristics on the gate roadways stability

Purpose. The research is aimed at determining the specifics of the influence of secondary support deformation characteristics on headgate stability in coal mines with steep-dipping seams. Methods. The deformation characteristics of secondary supports are determined in mine conditions based on instrumental observations of the displacement of reference points on the contour of headgate along the extraction site length. Secondary supports studied are in the form of coal pillars and timber packs. Findings. An assessment characteristic of the deformation properties of secondary supports is the ability to ensure the stability of side rocks and headgates in the mined-out space of the coal-rock mass. The determining factor in such an assessment is the load-bearing capacity of secondary supports. A distinctive peculiarity is a certain range of physical-mechanical characteristics and deformation processes, within which the resistance of supporting structures increases. At relative deformation ε ˂ 0.1-0.2, the resistance of coal pillars increases, which ensures the continuity of side rocks around the haulage drift and limits their displacement on the contour. After losing load-bearing capacity (ε ˃ 0.2), there is a periodic subsidence of the roof, which is accompanied by an increment in the displacement of side rocks on the headgate contour. In such conditions, the loss of cross-sectional area of the drifts exceeds 50%. For timber packs, after their compaction (ε = 0.4-0.5), resistance increases, effectively limiting the displacement of side rocks. The loss of cross-sectional area of the drifts does not exceed 30%. Originality. The dependence between the change in cross-sectional area (S) of the haulage drift and relative change in the volume of secondary supports per unit of convergence of side rocks ( ) has been determined. The presence of such dependence makes it possible to assess the state of headgates supported behind the stoping face at the extraction site. Practical implications. Coal pillars perform the functions of a supporting structure only within a certain range of deformation properties. Timber packs after their compaction allow limiting the displacement of side rocks on the headgate contour and ensuring its operational state.