Purpose. To develop a new approach for justifying rational parameters for mechanized thin seam extraction. Methodology. The approach was developed using a method of assessing the energy characteristics of the coal extraction process through mechanized means, specifically using longwall shearers. To determine the rational parameters, the primary energy characteristics were calculated, including: energy consumption for extracting 1 cubic meter of coal; benchmark consumption for extracting 1 cubic meter of coal; and overall extraction efficiency (the ratio of energy consumption to benchmark consumption). Findings. A new approach was proposed for rationalizing the parameters of coal extraction using longwall shearers. This involved applying the methodology for studying the energy characteristics of the extraction process. Based on the comparison of benchmark consumption and the consumption for extracting 1 cubic meter of coal, a rational application area for the most popular longwall shearers was identified. The study of the efficiency of the coal extraction process revealed that it is impractical to use drum shearers (KA80, KA200) in low thickness seams due to high energy consumption and limited adjustability of the executive body’s position in the longwall. It was also found impractical to use shearers designed for medium and high thickness seams (RKU10, RKU13) for low thickness seams due to low energy efficiency. Originality. A methodology was developed for evaluating the energy characteristics of longwall shearers depending on the type of executive body. Practical implications. The rational application area for longwall shearers on gently sloping seams was determined, as well as the overall efficiency of the coal extraction process using screw and drum executive bodies. It was established that modern extraction machines UKD400 and CLS-450 have relatively acceptable energy characteristics (with a generalized desirability criterion of 0.51–0.75, corresponding to satisfactory and good levels), but only within the specified passport characteristics range.

Purpose. To analyze composite materials and prospects of their use for roof support in coal mines. Research methodology. To achieve this purpose, we used analytical data on the market of composite materials, the volume of their production capacity, and cost indicators. Data on the physical and mechanical properties of composite materials and their quantitative indicators were used. Research results. The areas of application of composite materials in industry are analyzed and summarized. The analysis shows that composite materials are used in many areas of industry: medicine, construction, defense, etc. A comparative analysis of the physical and mechanical properties of carbon fiber-reinforced plasticand steel shows that this composite material has identical (and sometimes even better) properties than metal materials. The study concluded that it is better to use carbon fiber as a support material for mine workings in coal mines. The advantages and disadvantages of carbon fiber-reinforced plasticas a roofing material for coal mine workings are evaluated. It is clarified that the current limiting factor is the cost of carbon fiber-reinforced plastic, but over time, their price will decrease and their demand will increase. It is concluded that the use of this composite material in the elements of mine support can increase the pace of their implementation, reduce the labor intensity of the work performed and improve the working conditions of miners while lightening the structure. Scientific novelty. The physical and mechanical properties of composite materials have been analytically determined and it has been substantiated that carbon fiber-reinforced plasticsupports can be used in the support of preparatory workings in coal mines. Practical value. The obtained results prove that the support made of carbon fiber-reinforced plasticwill facilitate the design of the support, which, together with the acceleration of the shift operation, will contribute to the development of underground coal mining.

Мета.Запропонувати новий методичний підхід щодо комплексної оцінки вугледобувних підприємств на основі оцінки технологічних схем з точки зору їх сприйняття до інновацій в умовах диверсифікації

Purpose. To propose a new methodological approach to optimizing the parameters of the functioning of coal mines in the context of diversification. The methods. The production flows of coal mines are considered, as well as production functions. To solve the problem of diversification of production, the relationship between the types of resources expended, as well as the level of production in the form of raw materials, was compared. Based on the production function of Cobb-Douglas, a model of life support for the operation of a coal mine is built, considering the possibility of diversifying the activity. Findings. For the first time, the paper proposes a model for optimizing the parameters of mining in the context of diversification, which demonstrates the ratio of production functions and resources. With the help of the developed model, it is possible to trace in time the efficiency of the use of production resources, to determine the volume of production, to calculate the main parameters of the functioning of coal mines, to study at the expense of which resources the increase in productivity is achieved. The originality. For the first time, the possibility of diversifying mining activities by changing production flows is considered. Methodological recommendations for assessing the production activity of the mining complex are given. In this work, for the first time, to improve the efficiency of coal mines functioning, the internal potential of the technological scheme is considered, and the components that form it are analyzed. This made it possible to form management decisions, which consist in determining the volume of production, as well as the ratio between the attracted resources necessary to ensure the specified volume of production, constant monitoring of the use of resources, by establishing a rational ratio between fixed assets, labor, material resources; as well as establishing the interchangeability of productive flows in the aggregate balance sheet. Practical implementation. For practical application, the paper proposes a method for determining the rational volume of production from the standpoint of optimizing the production activities of an enterprise, as well as the ratio of production resources to achieve a given scale of production. Thus, there is an increase in capital productivity with the same degree of use of fixed assets, labor, materials. For the full and effective use of the technology, a specific example was considered to determine the optimal method of manufacturing products for a coal mining enterprise.

A method for optimizing the protecting pillars parameters during the study of soft enclosing rocks (in Ukraine mines) is represented. The necessity of a differentiated approach has been substantiated when choosing the protecting pillar parameters based on the geomechanical factors analysis influencing the state of massif. Mining and geological situation was analysed. It has been studied a stress-strain state (SSS) along the protecting pillar width with account of the mined-out space on the basis of a computational experiment and is presented in the form of curves of vertical and horizontal stresses distribution, as well as stresses intensity distribution. The recommended engineering decisions have been substantiated and the SSS of fastening and security structures has been analysed. A certain reserve of the fastening structure loadbearing capacity as part of the frame support and the combined roof-bolting system has been revealed. An evidence base has been created for the measures development on conducting and maintaining mine workings in the zone of the stope works influence. The recommendations have been developed on the protecting pillar formation with a width of at least 40 – 45 m to exclude the stope works influence.

Запропоновано новий підхід щодо механізму оцінки доцільності підтримки виробничих потужностей збиткових шахт Донецької та Дніпропетровської областей.Для вирішення поставленої проблеми застосовано комплексний підхід, який включає оцінку інвестиційної привабливості підприємства, визначення виробничого потенціалу, визначення можливості переходу на беззбитковий режим

The purpose of this study is to determine the nature of influence of the rheological properties of the rocks on the results of computational experiments simulating the mine workings contour condition during the breakage face advance. To determine the deformations along the mine workings contour, the calculations have been made of the junction area between the preparatory and stope face mine workings by the finite element method for various parameters of the material models. These data provided the basis for analysis of the patterns development of the rheology modelling influence on the stress-strain state of the geomechanical system. The obtained patterns are described by a function of many variables, and this function determines the limit and degree of rheology effect on the results of calculations. For the first time this pattern takes into account the heterogeneity of the rheological characteristics of rocks and the specifics of the computational domain geometry. The use of the obtained patterns makes it possible to simplify significantly the process of modelling in time and space of the geomechanical systems, which have a complex structure describing the interaction of several objects.

Objective is to propose a new approach to investment allocation in the group of coal-mining enterprises.Methods.To solve the specified objective, a complex approach has been applied including assessment of enterprise investment attractiveness, determination of production potential, and definition of the possibility to switch to a break-even mode.The process of planning the ways to save industrial potential of coal-mining regions may be considered as the representation of multidimensional space (initial and design values) in terms of the one-dimensional (amount of investment money) one.Findings.It has been established that the stage dealing with the development of a model for managing processes for mine unprofitability reduction should involve consideration of 8-10 factorial features, which may determine the formation of economic potential, taking into account peculiarities of the remaining deposits and their quality, as the integral assessment of mine potential in terms of both state and non-state investments.The formulated objective means selection of the minimum number of factors, which would reflect in the most adequate way the internal potential of a mine expressed by economic added valueas a consequence of interaction of factors of coal mine economic activities in specific mining, geological, and technological conditions.Originality of the research is in the fact that it is expedient to use an indicator of economic reliability, which synthesizes the capacity of links, economic level of technical and economic indicators, and the amount of remaining deposits, as a complex component of the level of an unprofitable mine.The mentioned indicators determine the residual life of the mine.Their physical content is not identical; and it is the fact that helps (in terms of their joint use) obtain more complete estimate than when using any single indicator.Practical implications.Practical significance includes actual assessment of the state of Donbas coal enterprises and determination of marginal break-even indicators, which has made it possible to elaborate recommendations for attracting financial resources.

Purpose.To create a model allowing integration of the diverse features identified for the rock massif behavior by differentiation of various theories and real phenomena into a single information-analytical flow.Methods.System analysis of computational experiments' results was based on the use of recursive calculation methodology for assessing accuracy of the obtained results with different methods of geometric and physical description applied to individual elements of simulation in the computational domain.Findings.Sample tables were obtained containing the acceptable values of weight characteristics for the various simulated elements in the generalized computational domain.A recursive algorithm for the analysis of the studied objects description' efficiency in the solution of geomechanics problems by grid numerical methods was formulated and implemented as a computational module.The authors created a system for the assessment of the results obtained via computational experiment at the time of full-scale investigation, which provides a comprehensive analysis of changes in the rock massif state during the operation of the selected support system.The conditions of combining the design characteristics of the simulated support elements functioning in a single load-carrying system under dynamic redistribution of forces were obtained.Originality.The resulting generalized model of mine working and elements affecting its condition allows to determine most accurately the nature of changes in the stress-strain state of geotechnological system regardless of the originally a priori specified limitations.Practical implications.The unified approach can be used in the search for the optimal parameters of implementing combined working supports in the area of mining operations and beyond.

Purpose. Substantiating the method for forecasting rock pressure manifestation in the system "layered massif working support" on the basis of displacement patterns detection at any arbitrary point of the preparatory working circuit during the computational experiments.Methods. Computational experiments were carried out on the basis of the finite element method using the solid computational domain, provided superlimiting non-linear behavior of the simulated materials. The use of numerical grid methods allows creating geometrically and physically complex simulation models and manipulate their state within a wide range.Findings. The calculations defined that with weak links between adjacent strata, acting shear stresses destroy them in the vicinity of working, and the contiguous rock strata deform with mutual sliding. Analysis of reduced stress area allows to substantiate with accuracy sufficient for mining computations a unified average structure of the computational domain that most comprehensively reflects all the main features of a real mining massif which are likely to influence computational error. This choice ensures the introduced error value within 10% in the entire range of mechanical parameters change of the rock massif strata.Originality. Stress-strain state of frame support and patterns of its change with increasing mining depth are non-linear, especially with nearby rock strata entering the superlimiting state; formation of the plastic hinges system along the frame support circuit, which causes the development of such replacements that exclude the possibility of further working exploitation.Practical implications. The proposed method allows to determine the optimal indicators of maintaining a working driven in the finely-layered rock massif, which makes it possible to significantly reduce operation costs.

Purpose. To develop a new approach to feasibility assessment mechanism of supporting production facilities of loss-making mines in Donetsk and Dnipropetrovsk regions. Methods. To solve the objective set, a complex approach was used including assessment of enterprise investment attractiveness, determination of production potential, definition of the ability to switch to a break-even mode. The process for planning ways to save the industrial potential of coal-mining regions may be considered as the reflection of multidimensional space (initial and design values) into the one-dimensional (amount of investment money). Findings. It has been established that on the stage of building a model for managing mine unprofitability decrease processes, it is necessary to overview 8-10 factorial features, which may determine the formation of economic potential, taking into consideration peculiarities of remaining deposit bedding and their quality, as integral assessment of mine potential in terms of (state and non-state) investment perception. The objective set comes down to selection of the minimum number of factors, which would the most adequately reflect the mine internal potential expressed by economic value added – as a consequence of interaction of factors of coal mine economic activities in specific mining, geological and technological conditions. Originality. The academic novelty is that as a complex component of the state of the loss-making mine, it is reasonable to use an indicator of economic reliability, which synthesizes the capacity of links, economic level of technical and economic indicators and the amount of remaining deposits. The latter determine the residual life of the mine, physical content of the proposed indicators is not identical, and it Физико-технические проблемы горного производства 2020, вып. 22 153 is this fact, which allows for their joint use to obtain a more complete estimate than when using any single indicator. Practical implications. Practical significance includes actual assessment of the state of Donbass coal enterprises and determination of marginal break-even indicators, which allowed for the formation of recommendations for attracting financial resources.

At the article considered natural and industrial factors that allowing to establish the boundaries of rational recovery ratio which the interaction is predetermined by the level of economic results of mines work. Thus, the preconditions were created for the ranking of the mines on the basis of reserves complex assessment.

The problem of traction coefficient variation of mining sectional locomotive while motion on the curvilinear rail track is observed. The relation of force of hydrodynamic wheel unloading taking into account the intermediate layer existence is defined. Quasistatic model of mining locomotive negotiation in turnings is developed. Verification of the developed model is provided by the system of non-linear differential equations. Empirical friction coefficient relations subject to the rail track radius for velocities 3 and 5 m/s are defined.

A solution of topical scientific problem of coal shearer output increase providing minimum specific power supply for coal cutting, transportation, and loading in terms of thin seams has been proposed. The solution is based on the use of earlier proposed criterion of screw gumming for optimum cutting velocity-coal shearer feed rate ratio in the context of increased screw rotation owing to phase voltage frequency increase. Simulation results of automated control system for coal shearer operations with frequency-controlled cutting drive within thin seams have confirmed the efficiency of the system using proposed algorithm of smart analysis of coal shearer power signal.