Purpose. Determining the conditions and parameters for ensuring the stability of the coal seam roof with a yielding support in the area adjacent to face and behind it under the influence of dynamic loads based on the analytical and laboratory studies. Methods.To achieve the purpose set, analytical studies have been carried out using the basic principles of the theory of elasticity and vibrations, the hypothesis of girders and the hinged-block displacement of the stratified rock stratum. Also, the laboratory studies of models from equivalent materials have been performed, in which the coal seam roof is presented in the form of a girder having a yielding support with variable rigidity from the filling material under dynamic load.Findings. As a result of performed studies, the phenomenon has been determined that the condition for the stability of the coal seam roof is a geometric parameter that reflects moving of the girder with a yielding support, under the force impact of a falling load with a known mass and the physical-geometrical characteristics of the deformable system. It has been determined that as a result of a change in the spans length, a change in the flexural rigidity of the girder occurs, which means that the yield influence of the same supports on the stability of the coal seam roof is different. The values have been set and the relationship has been studied of the physical-mechanical characteristics of the filling mass as a yielding support.Originality. It has been proven scientifically that the stress-strain state (SSS) of a system in which the coal seam roof is studied as a girder depends on the physical-geometrical characteristics of the system, as well as the type and place of applying the external load, in case when the law of the girder movement in time is determined.Practical implications. The effective supporting of the undermined rock stratum in the working part of the longwall face and behind the face is achieved by placing the yielding supports in the mined-out space or by using the backfill in the mined-out space while conducting the stope operations, thus, increasing the efficiency of measures to protect the labour of miners in coal mines.

The purpose of the work. Studying the stability of haulage drifts of steep coal seams with the method of protecting coal by pillars. An integrated approach was used as research methods, including: a full-scale experiment, analytical studies, interpretation of the results obtained. To assess the durability of mine workings, full-scale experiments were carried out to study the manifestations of rock pressure in the haulage drifts with the method of protecting coal by pillars, when the magnitude of the change in the cross-sectional area and the convergence of side rocks on the contour of the development workings along the length of the excavation section was established. It is fixed that at the maximum relative deformation of coal pillars (ε ≈ 0,7), the loss of the cross-sectional area of the haulage drifts at a distance of l ≥ 60 m behind the working face is more than 50 %, which does not correspond to the operational state of the workings. When studying the deformation properties of protective structures, it was found that after their deformation by 10–20 %, an increase in the convergence of side rocks in the haulage drifts begins, a distortion of the shape and loss of the bearing capacity of coal pillars. The distortion of the shape of the security structures contributes to the intensification of the displacements of the roof on the contour and is accompanied by a deterioration in the durability of the haulage drifts in the excavation areas of the coal mine. It has been proved that on a steep drop, with the method of protecting the haulage drifts with coal pillars, the change in the cross-sectional area of the excavation occurs along a linear relationship with an increase in the length of the excavation section due to the distortion of the shape and loss of the bearing capacity of the security structures. To improve the safety of miners in the excavation areas of coal mines developed steeply falling coal seams, it is recommended to abandon the method of protecting the haulage drifts with coal pillars. To avoid emergencies associated with the collapse of the roof, it seems advisable to use purposeless methods of protection – flexible structures or backfilling of the goaf.

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