Kayun O. Improvement of methods of protection of preparatory workings of steep coal seams in deep mines

The dissertation solves the urgent scientific and technical task of improving the methods of protecting the preparatory workings of steep coal seams in deep mines by using the laws of geomechanical phenomena that manifest themselves during the unloading of the coal-bearing massif and contribute to the preservation of the integrity of the roof in the created space, when managing its condition in the process of deformation of flexible protective structures, their modification and increase in resistance takes place, which leads over time to a gradual decrease in the increase in lateral rock displacements on the contour of the rollback stretches and stabilization of the load on the arch support along the length of the excavation section, which creates conditions for ensuring the operational condition of the workings. The idea of the work was to perform the regularities of geomechanical phenomena that appear during the unloading of the coal massif and their influence on the deformation processes in the coal massif, taking into account the characteristics of the load transfer to the arch fastening of the preparatory mine workings to ensure the operational condition of the mining areas in deep mines with steep seams. The aim of the work was to improve the methods of protection of the preparatory mine workings of steep coal seams in deep mines, to ensure their operational condition along the length of the excavation section. The following tasks were set and solved in the work: an analysis of the study of the issues of ensuring the stability of preparatory workings for improving the methods of their protection in the excavation areas of coal mines with a steep occurrence of layers was performed; determined conditions of stability of side rocks in the coal massif with various methods of protection of preparatory works to ensure their operational condition; laboratory studies of the deformation properties of protective structures of preparatory workings under compression conditions were performed and their influence on the stability of side rocks in the coal massif was determined; full-scale studies of the stability of preparatory workings of steep formations were performed and an assessment of their operational condition along the length of excavation sections was established; developed methods of protection of preparatory mine workings, which are aimed at ensuring their operational condition. The object of the study was the processes of managing the state of side rocks in a coal massif with preparatory mining. The subject of the study was the patterns of changes in the stress-strain state of side rocks and protective structures in a coal-bearing matrix with preparatory mining operations. The work uses a complex approach, which includes: analysis of known studies and their generalization; analytical and laboratory studies of the stability of side rocks and deformation properties of protective structures of preparatory works; mine instrumental observations of the stability of preparatory workings of steep layers with different methods of protection along the length of the excavation section; analysis and interpretation of the obtained results; methods of theory of elasticity, classical mechanics and geomechanics and planning of experiments. We received further development of the study of the patterns of deformation of protective structures of preparatory mine workings, which allow us to assert that their operational condition with various methods of protection in deep coal mines with steep seams is achieved due to the preservation of the integrity of the side rocks in the produced space of the excavation sections, when during the unloading of coal-bearing of the massif, there is a modification of superstructures and an increase in their stiffness while ensuring the load-bearing capacity. It is experimentally substantiated that under the action of external compressive force and relative deformation (??) of protective structures up to a certain limit (0,1≤??≤0,6), their modification occurs due to a change in specific potential energy, which leads to an increase in their resistance at the simultaneous transformation of shape and volume, when when using flexible protective structures y within the limits of 0≤??≤0,2, there is a decrease in stiffness, and then its increase by 1,5-2 times at values of 0,4≤??≤0,6, due to which creates conditions for preserving the integrity of side rocks and rigid protective structures, when within the limits of the change in relative deformation 0≤??≤0,1, the resistance of the structure temporarily increases, after which their destruction and strength decrease occur, as a result of which the side rocks collapse, and the state of preparatory the product deteriorates.