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.

Purpose: To determine the parameters of detached rock packs with compensating voids. Methodology: Analysis of technologies for the protection of development workings, based on the management of the stress-strain state of rocks around the workings, physical modeling using equivalent materials, numerical modeling by the finite element method, and methods of structural mechanics. Results: In the conditions of soft soil rocks the expediency of application of protection means based on management of a stress-strain condition in a surrounding massif and redirection of extrusion forces from a working has been substantiated. On the basis of analysis of the existing protection measures of the workings behind faces the prospects of use of protection technologies by means of construction of detached rock packs with limiting surfaces between which there are compensatory voids left, have been proved. To determine the parameters of such packs and voids between them in the conditions of soft soil rocks, a set of laboratory and numerical studies has been performed. According to their results, it has been established that to ensure the redirection of extrusion forces from the working it is necessary to build rock packs with limiting surfaces in the form of rectangular parallelepipeds with orientation of their greater side perpendicular to the longitudinal axis of production and trapezoidal prisms with their narrower orientation towards the working. Recommendations on the parameters of these structures and compensatory voids between them in the conditions of soft soil rocks have been formulated. Scientific novelty: On the basis of numerical modeling the regularities of stress distribution in rocks under detached rock packs of different shapes have been investigated, which allowed substantiating the parameters of the last and compensatory voids between them to ensure the stability of workings in the soft soil rocks. Practical significance: The expediency of application of technologies of protection of preparatory workings behind faces in the conditions of soft soil rocks by means of rock packs with limiting surfaces between which there are compensatory voids has been proved, and their parameters have been defined.

No abstract

Objective: Based on the review of the array of publications to analyze the methods and models of general risk assessment, the nature of industrial risks and management processes on the examples of labor of coal miners. Propose a classification of mathematical models of industrial risk and identify the most appropriate model for the work of miners in the stochastic system “man-machine-environment”. Methodology: Applied to the use of situational analysis, qualimetry, probability theory and risk theory, methods of classification of occupational risks. Results: Based on a systematic analysis of multifactorial risks of emergency situations, the essence of industrial risks and management processes on the examples of coal miners, the dominant causes of industrial risk in the ergatic system (“man – machine – environment”), models and methods of risk research. Scientific novelty: For the first time on the basis of the analysis of the reasons, dynamics and consequences of industrial risks the classification of mathematical models of risks which are adapted to ergatic systems of mine production is offered. Practical value: The need for adequate practical application of risk methods and models for the assessment and measurement of industrial hazards has been proven.