ASSESSMENT OF STABILITY OF PREPARATORY MINE WORKINGS WITH CAST STRIP PROTECTION

Abstract

Purpose. To assess the stability of the preparatory mine workings with the method of protection with cast strips in order to ensure safe working conditions in the mining areas of the coal mine. Method. A comprehensive approach was used in the research, which included the analysis and generalisation of theoretical and experimental research on this problem, a mine experiment in the conditions of the Pokrovske Mining and Metallurgical Mining and Processing Plant, and the processing of experimental data. The results. As a result of the conducted research, an assessment of the stability of the preparatory mine work with the method of cast strip protection was established. Deformation processes in the coal massif around the preparatory production were considered during its unloading under the conditions of the static load of the protective structure. The analysis of the change in the increase in displacement of the roof indicates that the security structure is deformed under loading by external forces. As the cleaning hole moves, when the length of the preparatory work increases, the displacement of the side rocks on the contour increases. Depending on the position of the cleaning hole, the cross-section of the preparatory work is reduced due to the effect on the fastening of the pressure of the loaded rocks. It was established that within the limits of the deformation resource of the cast strip, when its relative deformation is within 0≤ε≤0.3, the loss of the cross-sectional area of ​​the preparatory work does not exceed 15%, which ensures safe working conditions for miners at the excavation site. In conditions where the relative deformation of the security structure increases (0.35≤ε≤0.65), there is a loss of the load-bearing capacity of the security structure, which is accompanied by an increase in the displacement of the roof on the contour (more than 40 mm) and deformation of the fastening. At the same time, the loss of the cross-sectional area of ​​the product is more than 40-42% and the level of the threat of roof collapse is approaching a critical state. Scientific novelty. A type of functional dependence has been established between the change in the relative deformation ε of the protective structure, which is under static load in the coal massif, and the cross-sectional area S (m2) of the preparatory work, according to which its condition is evaluated according to the length of the excavation site. Practical meaning. The use of cast strips for the protection of preparatory mine workings allows ensuring their operational condition within the limits of the deformation resource of protective structures. Keywords: preparatory work, operating condition, side rocks, protective structures, roof displacement, deformation, work safety.