In modern pedagogical and engineering education studies, technological competence is viewed as a multidimensional construct essential for preparing future specialists for the digital economy, automated transport systems, and changing industrial standards. It combines technical knowledge and skills with motivational readiness, cognitive depth, and practical action. In this context, specialised auto- game simulators are relevant for ensuring continuity between general secondary education and higher professional training. The aim of the study is to conduct a theoretical and methodological analysis of auto-game simulators as a multifunctional tool for forming technological competence and to determine the role of simulation environments in ensuring educational continuity between the “Automation and Robotics” school module and the professional training of bachelors majoring in “Professional Education (Transport)”. Methods. The article uses theoretical analysis, synthesis, comparison, and generalisation of pedagogical, technical, and psychological studies on gamification, STEM education, and computer modelling. Systematic analysis of regulatory documents and educational standards was applied to clarify the components of competence, while pedagogical modelling enabled the development of educational scenarios and the classification of software products according to their didactic potential in the transport industry. Within theoretical analysis, the simulator is interpreted not as an entertainment tool but as a high- tech virtual laboratory. It is shown that the effectiveness of forming technological competence depends on the integration of simulation environments that ensure the interaction of motivational, cognitive, and active components. The study substantiates that auto-game simulators, such as BeamNG.drive, provide a unique platform for studying soft-body physics and the functional limits of electronic systems under various conditions. Particular attention is paid to the principle of continuity, where the simulator transforms from a visualisation tool in middle and high school into a professional diagnostic instrument at the university level. It has been proven that built-in analytics, telemetry data, and replay mechanisms allow students to move from a driver’s perspective to an engineer’s perspective. The study describes practical cases where modelling critical states and electronic system failures, such as ABS, ESP, and cruise control, promotes critical technical thinking and the ability to predict the consequences of technical decisions. Particular emphasis is placed on the STEM approach as a factor in developing technological adaptability. The research shows that regular work with simulations activates problem-solving mechanisms, promotes functional understanding of complex mechanical-electronic interactions, and increases the accuracy of technical assessment. Bilingualism in technical documentation and software interfaces is also considered as a resource for professional growth. The integration of such high-fidelity environments is viewed as an important cognitive and professional resource for adaptation to the technological context of the transport industry. Conclusions. It is substantiated that the formation of technological competence is an integrative process formed through the interaction of pedagogical strategies, high-tech simulation tools, and continuity of educational stages. Auto-game simulators are key resources for developing effective technical regulation, adaptive professional behaviour, and engineering control in the transition from school to higher education. The obtained generalisations can be used in further empirical research, vocational teacher training, updated “Technology” curricula, and innovative STEM programmes for the transport sector.

Purpose. To determine the effective parameters of a resource-saving technology for supporting and protecting a panel entry during its repeated use based on experimental studies and multifactor computer modeling. Methods. The study employed both experimental and numerical research methods. The experimental part included in-mine observations of rock pressure manifestations in repeatedly used extraction workings of the Western Donbas. The state of the workings was assessed by the displacement of the drift contour and parameters of frame support deformation in key cross-sections. Numerical modelling of the geomechanical state of the rock mass and support systems was performed using the ANSYS software package based on the finite element method (FEM), taking into account the texture of the coal-bearing stratum, physical and mechanical properties of lithotypes, moisture content, fracturing, rheological properties of rocks, and disruption of contacts between adjacent layers. Findings. Based on experimental studies and numerical modelling, the effectiveness of using rope crown runners in combination with a combined roof-bolting system has been proven. It has been established that the proposed support scheme reduces the intensity of rock pressure manifestations and ensures significant savings in material and labour resources during the repeated use of mine workings. The feasibility of its application for supporting prefabricated drifts under complex mining and geological conditions of the Western Donbas has been confirmed. Originality. The features of the formation of the stress-strain state of the rock mass surrounding an extraction working during its repeated use have been established, and the effectiveness of a combined roof-bolting system with rope crown runners for reducing rock pressure manifestations has been substantiated. New data on the redistribution of stresses in the roof and side rocks of the working have been obtained, explaining the mechanism of increasing its stability when using the proposed support system. Practical implications. The results of the study can be used in the design and selection of resource-saving support schemes for repeatedly used drifts under conditions of weak surrounding rocks and increased rock pressure manifestations.

Purpose. The purpose of this research is to group the mining-geological conditions of a stratified mass containing weak rocks in the Western Donbas (Ukraine) and to substantiate recommendations for rational supporting and protecting system parameters for reused mine workings. Methods. The research was conducted by combining analytical methods for studying the processes of rock mass deformation in the zone of stope operations with experimental measurements of rock pressure manifestations. As a connecting link, ideas about the development mechanism of the coal-overlaying formation shear process and its peculiarities for the mining-geological conditions of the Western Donbas were studied. The obtained patterns were taken into account in the calculation model as a component of load formation, as well as in supporting and protecting system for extraction drifts. A methodology for computer modeling was determined based on the condition of the maximum possible representation of the design peculiarities of frame and roof-bolting supports. The developed models were tested, which confirmed their adequacy to real objects. Findings. The complex of conducted studies made it possible to develop an array of calculated texture variants that reflect the probability of dividing lithotypes by their thickness in the rock layers of the immediate and main roof and bottom. Based on the results of a number of computational experiments to study the effectiveness of the recommended options for supporting and protecting systems, the distribution of the stress-strain state in the load-bearing elements of the system has been determined. Principles of grouping of mine working maintenance schemes have been created, which cover most of the mining-geological conditions of mines in Western Donbas. Originality. To achieve the reliability of the results, a complex of peculiarities and mutual influence of the geomechanical system elements has been studied. The patterns obtained as a result of multifactorial modeling have revealed the link between the strengthening of rock layers in the form of their discrete disturbance and the formation of a system of interacting plates, which intensifies the process of pressing-out a partially strengthened border mass. Practical implications. The novelty of the research is in generalized principles of grouping structural-technological schemes for maintaining extraction drifts. As a result, three groups of mining-geological conditions for the operation of extraction drifts planned for reuse have been identified. Three variants of schemes for maintaining extraction drifts for the conditions of mines in the Western Donbas have been proposed and studied.

The multi-parameter nature of the coal mine methane utilization process as a component of the concept of complex mining and processing of mineral raw materials is examined. A geomechanical substantiation and prediction of outgassing volumes in the perspective of complete mining of coal reserves in Western Donbas is proposed. The experience of technological solutions for methane outgassing and utilization both at operating extraction sites and in already mined-out field areas has been summarized. The main generalized options for complete reserve mining are considered in terms of the geomechanics peculiarities of development of the destruction and weakening zones. The schemes of coal-overlaying formation rock shear for the “checkerboard” and simultaneous procedures of complete coal seam reserve mining have been analyzed in detail. Patterns of the most influential geomechanical factors on the distribution of disturbed rock zones have been obtained, which makes it possible to assess the reliability of the ideas using experimental information on change in the load of powered support sections in real time. The resulting solutions make it possible to predict outgassing in each of the existing situations.

Purpose. To substantiate the rational parameters of support made of composite materials for mine workings in coal mines located at depths exceeding 1,000 meters. Methodology. The finite element method in the Ansys Mechanical environment was employed in the study. The comprehensive research approach involved collecting and analyzing input data, preparing and conducting a computational experiment, and subsequently analyzing the obtained results. Findings. For the first time, an algorithm has been developed for determining the rational parameters of the support system, which, through computational experiments, accounts for the support cross-section, rod cross-section, the number of anchors, and their positioning – factors significantly influencing the operational characteristics of the support. The results of stress-strain state (SSS) modeling of the improved support system allowed for the substantiation of rational parameters for composite support. The research led to the development of an algorithm for selecting rational parameters for the composite support system in the conditions of PJSC Mine Administration “Pokrovske”. A methodology for determining rational composite support parameters has been developed, based on applying an algorithm for selecting the optimal support cross-section, which allows choosing a rational support cross-section, yielding rod, and support installation step. Originality. The study identifies trends in the stress level variations within the rock mass and elements of the composite support system. The intensity of stress (σ) in the composite support system increases with a higher H/R ratio, equivalent to an increase in rock mass load. Conversely, the stress intensity (σ) decreases as the composite support cross-section increases, reducing the load on support elements. Practical value. The proposed methodology can be used as an addition to current regulatory documents on mine working support at depths exceeding 1,000 meters.

Abstract The paper examines a promising component for the energy sector – development of gas reserves and gas production, taking into account the peculiarities of mining-geological and mining-technical conditions of the Western Donbas deposits (Ukraine). Two components of the solution to this issue are analyzed: the texture and physical-mechanical properties of weakly metamorphosed rocks and the use of high-performance complexes, reuse of extraction drifts with resource-saving technologies for their maintenance. Based on multivariate computational experiments, schemes have been developed to determine parameters for the location of outgassing wells. Three basic methodological provisions based on the conducted analytical research performed by the finite element method have been substantiated. Calculations, which are the basis for the methodology of selecting outgassing well location parameters, have been conducted. Experimental measurements conducted at six extraction sites of two mines confirm that the outgassing coefficient according to the recommended parameters exceeds that corresponding to the existing outgassing well location schemes in mines (the range of relative increase in the outgassing coefficient is from 19 % to 123 %). In addition, a significant influence (up to 35 – 60 %) has been revealed of the coal-overlaying formation texture, the well gradient angle (20 – 30 %), and the drilling step of outgassing wells (30 – 40 %). It has been found that an increase in the longwall face advance velocity improves the gas trapping efficiency by 25 – 40 %, leading to a decrease in the methane flow into adjacent mine workings and substantiates an opportunity to accelerate the longwall face advance.

Purpose.The research aims to substantiate the general provisions on coordination of the experimental-analytical research results of the influence of pre-drilled wells on the intensity of gas-dynamic phenomena manifestations (using the example of the mining-geological conditions of the phenomena at the PJSC Mine Administration Pokrovske, Ukraine). Methods. The research uses an integrated methodology consisting of indirect experimental methods for studying the adjacent rock mass state and tendencies. Findings. It has been proven that indirect experimental indicators of the rock mass state around the tunneling face are related to the peculiarities of the distribution of its stress-strain state components. Based on this research, the well lengths of up to 10-15 m has been determined to effectively and safely de-stress the rock mass. The experimental research validity is confirmed by conducted computational experiments, in the course of which the dependence of the propagation parameters of the stress-strain state component concentrations on the degree of hardness of the lithotypes is revealed, and a geomechanical substantiation to the tendencies of propagation of rock pressure anomalies near stoping and tunneling faces is given. The new knowledge obtained is the basis for creating a method for calculating rational parameters for the location of de-stressing pre-drilled wells. Originality. An objective assessment of the degree of adequacy and reliability of the computational experiment results has been made under the condition of using a new geomechanical model with mine studies of seismic-acoustic signal parameters and the initial gas release velocity. The main tendencies of vertical σу, horizontal σх and σz, as well as stress intensity propagation have been identified. The obtained results of exploring the bottom-hole mass are aimed at substantiating the parameters of anti-outburst measures for all preparatory mine workings. Practical implications. The conducted research is implemented in creation of a calculation method and recommendations for the selection of rational parameters for the location of de-stressing pre-drilled wells for the purpose of weakening the rock mass, surrounding the tunneling face, and reducing the probability of gas-dynamic phenomena occurrence due to the controlled weakening of adjacent rocks.

The paper deals with the issues of substantiating the parameters of location outgassing wells, determining their expedient routes in the mining-geological and mining-technical Western Donbas conditions. Based on the conducted multifactorial computer experiment, the patterns have been obtained of influence of the coal-overlaying formation texture on the parameters of its shear into the mined- out area. When determining the patterns of influence of mechanical properties of the coal-overlaying formation lithotypes, they are divided into three generalized groups: low, averaged, high. At the same time, the influence of the height and distan.e parameters the strongest and hardest lithotype occurrence, such as sandstone, has been studied. It is noted that with low mechanical characteristics, the gradient angle of the line of changing curvature sign of the rock layers bending in the direction of the coal seam dip is steadily decreasing. Conditions have been identified and criteria have been developed for the most effective routes for the location of site outgassing wells. The developed criteria, in combination with the dependences of the coal seam shear parameters, make it possible to create a methodology for determining the expedient coordinates for drilling outgassing wells based on the results of modeling by the finite element method.

The paper deals with multi-component complex mining of mineral raw materials in the context of sustainable development and its important component – coal mine methane utilization and its conversion into thermal and electrical energy. The conducted analysis of scientific and practical experience has shown the multi-parameter nature of this process and the influence of a large number of factors. The mining-geological conditions of the Western Donbas (Ukraine) are substantiated as the research object, which makes it possible to limit the variation of geomechanical factors, as well as to develop basic provisions and general principles for reasoning predictive assessments of outgassing during complete mining of coal reserves. The dependence of gas volume on specific gas content of lithotypes and the volume of their destruction related to the coal-bearing stratum shear mechanisms at different options of complete mining of the Western Donbas coal reserves, is presented. The patterns of influence of the main geomechanical factors on the propagation of disturbed rock zones are substantiated.

Purpose. Rationale for the integrated use of the resource potential of coal-mining enterprises, which is aimed at obtaining technical and drinking water for their own production needs, local population and obtaining valuable substances from desalination waste. Methodology. Analysis of world experience, information about aquifer complexes in the Western Donbas mines, conducting chemical analyses of mine waters and salt mixtures obtained after using reverse osmosis products. Results. Based on the accumulated world experience in desalination of highly mineralized waters, it can be concluded that it is possible to effectively implement this experience at mining enterprises. Description of aquifer complexes has been given in detail using the example of the Zakhidno-Donbaska Mine of PJSC “DTEK Pavlohradvuhillia”, chemical analyses of water before and after discharge into settling ponds. A rational technological scheme for desalination, volumes of purified water obtained for drinking and technical water supply, as well as the quantitative and qualitative composition of the dry residue components of mine water desalination waste, and recommendations on possible use of products on the market have been determined. Scientific novelty. Analytical and laboratory studies have been conducted to determine the component composition of mine water desalination waste from Western Donbas coal-mining enterprises. It has been determined that the resulting salt product is a mixture of pure salts and valuable microcomponents, and the resulting distillate is fuel for the operation of hydrogen electrolyzers, which creates prerequisites for modern “green” hydrogen energy infrastructure. Practical significance. The qualitative and quantitative mine water parameters on complex use as an alternative source of water supply and obtaining related reverse osmosis products have been analyzed. The road services propose the consumption of the resulting salt products by municipal enterprises, and the dry distillation residue – to prevent dust. This approach allows solving not only the problem of desalination waste utilization, but also applying the separated valuable substances in the industrial market of food, medical, cosmetic, paint and varnish, chemical, as well as building materials, plastics and polymers production industries. Keywords: mine water, waste recycling, mineral resource, coal-mining enterprises.

Purpose. The research purpose is to study the mechanism of the influence of geomechanical-technological factors on the location parameters of the gas-drainage wells behind the longwall face in the area of stope operations under the conditions of weakly metamorphosed rocks. Research methodology. An integrated approach is used, including an analysis of existing research on the gas release patterns in the mine workings of extraction sites and local gas-drainage parameters, analysis of geomechanical processes, development of schemes for modeling by the finite element method, substantiation of methodological approaches for conducting experimental research into the rock pressure manifestations in extraction working, taking into account existing tendencies of the influence of stoping face advance velocity. Research results. The views on the mechanism of the stratified mass texture transformations of weak rocks have been developed during the study of the optimal extraction site gas-drainage parameters. The deformation development schemes have been constructed for any layer of the main roof behind the area of longwall face conjugation with the extraction working, displacement of coal-overlaying formation rocks along and across the extraction site with the location of gas-drainage wells. Based on the conducted research, recommendations on the rational location of gas-drainage wells have been obtained. Scientific novelty. The main characteristics of the weakly metamorphosed rock displacement process in the area of stope operations are studied in a spatial formulation, and the mechanism of the influence of geomechanical-technological factors on the expedient location parameters of gas-drainage wells behind the longwall face is represented on the relevant schemes. Practical value. The reliability of the proposed location parameters for gas-drainage wells behind the longwall face in the conditions of weakly metamorphosed rocks of the Western Donbas has been analyzed, taking into account the stoping face advance increased velocities.The conclusions drawn on the basis of rock displacement tendencies in the coal-overlaying formation are summarized in the schemes for identifying the mechanism of rock mass deformation near the area of stope operations.

This paper studies the ways of solving the resource-saving direction of the strategy for the mining industry development in Ukraine. The existing ideas about the patterns of changing stress-strain state (SSS) in the mass during the stope mining of minerals are analyzed. The problem of the host rock SSS formation and development is studied. The main directions of studying the relationship between the parameters of mass SSS anomalies in the area of stope operations and their technological parameters has been substantiated with the selection of a methodology for conducting multivariate computational experiments. A macromodel has been constructed to calculate the change in the distribution fields of the rock mass SSS components with subsequent substantiation of its idealizations. The principles of matching the macromodel and the subordinate models have been studied. A new methodical approach is proposed for taking into account the time technological parameters (average daily face advance velocity and the duration of its stoppage) through their relationship with the mechanical characteristics of the rocks. A test assessment of the adequacy of the performed calculations based on the spatial model SSS analysis for all stress components has been conducted. The degree of influence of the stope face advance velocity and the mass texture on the parameters of rock pressure anomalies has been studied, as well as the linking patterns in the area of conducting stope operations have been obtained: frontal and lateral bearing pressure zones and a zone of destressing behind the stope face. A base has been created for studying and predicting the rock pressure manifestations in critical areas in order to develop recommendations for choosing rational technological and design parameters for high-rate mining of coal seams.

The paper provides a detailed analysis of innovative technologies for maintaining mine workings at great depths. The possibility of using composite materials (in particular, carbonfiber-reinforced plastic) as fastening elements is of special attention. It has been conducted a comparative analysis of the physical-mechanical properties of carbon fiber-reinforced plastic and low-alloy steel, traditionally used for the manufacture of frame support. To conduct a comparative analysis of the stress-strain state, a series of models has been developed and computer modelling has been performed by the finite element method using the Ansys Mechanical software product. In mining-geological conditions Pokrovske Mine Administration, three types of supports, namely, basic, composite with variable section and composite with constant section, have been studied. The initial and boundary conditions, as well as the assumptions and idealization of the model, have been substantiated. A comparative analysis of the stress intensity confirms the advantage of the proposed frame supports made of composite materials in terms of limiting the zones with maximum values. Laboratory research, conducted on a 3D-printer, testifies to the adequacy of conducted modelling. The reliability of the obtained values makes it possible to recommend an innovative support using carbon fiber-reinforced plastic for conducting a mine experiment.

The paper studies new approaches to substantiating the geomechanical model of a mining object, taking into account the Chaos Theory, where the slightest change in the initial conditions radically changes the behavior of the system as a whole. An algorithm for performing a multifactorial computational experiment with a change in the initial conditions has been formulated and implemented. It is proposed to solve applied problems by synthesizing geomechanical innovations, taking into account the mutually influencing elastic, plastic and rheological rock mass properties for the development of innovative technologies for mining minerals in a stochastic medium. The optimal fastening structure based on the study of the geomechanical system state is proposed. Thus, in the process of mining, a rock mass has been surveyed, which is characterized by a variety of manifestations and variability of each element in the studied object. This approach makes it possible to implement the principles of efficient use of resources in mining and, taking into account the Chaos Theory, to ensure systematic planning of research using mathematical modeling.

Purpose. The research purpose is to develop a concept for complex mining of mineral resources from coal mines using the example of PJSC DTEK Pavlohradvuhillia mines with a transition to multi-product production of clean drinking water, utilization of methane, secondary coal from rock dumps and sludge reservoirs, low-potential thermal energy of mine groundwaters and associated raw materials from desalination waste. Methods. The research uses an integrated approach, which includes an analysis of existing experience and available complex coal mining technologies, laboratory studies of mine water desalination technology by the reverse osmosis method with thermal distillation of concentrated brine, and chemical analysis using ElvaX laboratory equipment. Findings. This paper presents the research results of a comprehensive analysis of mineral raw material resources related to coal mining. The technically achievable energy potential that can be produced from the secondary coal of rock dumps and sludge reservoirs has been determined, which in total is 183.3 TJ. The annual heat potential of methane gas utilization has been estimated, which in total of PJSC DTEK Pavlohradvuhillia’s mines reaches 7.1 PJ. The possibility of extracting up to 1.12 TJ/year of associated thermal energy from the water-drainage installation of mine complexes has been determined. For the conditions of the Zakhidno-Donbaska mine, the authors of the paper have developed a technological scheme for the water preparation process by the reverse osmosis with the desalination brine treatment by the method of multistage evaporation on adiabatic evaporators. Originality. For the first time, the energy flows related to coal mining technology have been comprehensively analyzed for the possibility of their joint use to cover the needs of the mine complex. The prospects for complex mining of mineral resources have been assessed based on the adaptation of the mine complex production facilities to the multi-product production of clean drinking water, utilization of methane gas, low-potential thermal energy from mine groundwaters and secondary raw materials of desalination waste. Practical implications. The proposed set of technological solutions will ensure the sustainable development and diversification of the production of PJSC DTEK Pavlohradvuhillia coal-mining enterprises, as well as the effective transformation of coal-mining cities during the period of transition from mono-product production to the creation of multi-business production complexes that comply with ESG principles. The creation of multi-product mine complexes capable of producing not only coal, but also heat and associated mineral raw material resources, should become a guarantee of stable social-economic development of coal-mining regions.

Microwave stimulation is a new method for natural gas hydrate exploitation. In this study, methane hydrate was synthesized in quartz sand with a particle size of 106-150 mu m, and the decomposition characteristics were investigated using continuous and intermittent microwave heating. During the initial stage of continuous mi-crowave heating, methane hydrate decomposed immediately due to microwave stimulation. Subsequently, due to a decrease in microwave penetration depth, microwaves did not affect the areas further away from the mi-crowave source and macroscopic heat transfer became the main heat source for hydrate decomposition. The microwave power used during the study ranged from 200 W to 500 W. The results indicated that hydrate decomposition time decreased as power increased, and the average gas production rate increased at the same time. However, the energy efficiency ratio did not vary with the microwave power. The maximum energy ef-ficiency ratio was 1.320 at a microwave power of 400 W under continuous microwave heating. Compared with continuous microwave heating, intermittent microwave heating improved the efficiency ratio by 59.32 %, with a heating cycle involving microwave stimulation for 5 min (Microwave ON time) and no stimulation for 1 min (Microwave OFF period). As microwaves provide heat for hydrate decomposition, a high-speed gas production can be obtained. Heat reservoirs were utilized to maintain hydrate decomposition during the OFF period, which also resulted in energy saving. Although intermittent microwave heating reduced the average gas production rate slightly, it improved the energy efficiency significantly. Therefore, the number of heating cycles and microwave heating periods should be carefully considered to obtain high hydrate exploitation efficiency. Intermittent mi-crowave heating is recommended for hydrate exploitation to improve extraction efficiency and save energy.

W artykule rozważane są zagadnienia opracowania koncepcji mechanizmu wydobywania węgla ze złóż gazowych oraz dwóch składowych zaopatrzenia kraju w nośniki energii: wydobycie węgla i zagospodarowanie metanu z warstwy węglonośnej. Zagadnienia te są nierozerwalnie związane z eksploatacją złóż przodkami ścianowymi o dużych postępach. Badany jest rzeczywisty problem rozwiązania powyższych sprzeczności. Wzory wpływu czynników geomechanicznych na podstawie modelowania metodą elementów skończonych (MES) parametrów ścinania formacji nadkładkowych badane są pod kątem uzasadnienia schematów lokalizacyjnych dla otworów odgazowujących miejsca przy dużych prędkościach postępu przodków w Zachodnim Donbasie. Uzyskane wyniki eksperymentów obliczeniowych są porównywane z badaniami prowadzonymi przez specjalistów. Wnioski dotyczące stopnia oddziaływania czynników geomechanicznych i konieczności ich uwzględnienia są uzasadnione. Opracowano i uzasadniono trzy modele obliczeniowe pod względem kształtu i wielkości strefy obliczeniowej, tekstury górotworu, właściwości mechanicznych jego litotypu, warunków obciążenia na granicach modelu, charakterystyki związku naprężeń i odkształceń w elementy modelu oraz kryteria wyznaczania stanu granicznego. Wykazano istotny wpływ głębokości zalegania przodka oraz tekstury masy na parametry ścinania formacji nadkładu. Na podstawie danych z eksperymentów obliczeniowych otrzymano odpowiednie zależności i równania regresji. Przeprowadzone badania pozwalają na wybór odpowiednich schematów lokalizacji otworów odgazowujących.

Depressurization combined with thermal stimula-tion is a promising method for gas hydrate production. Owing to its advantages of rapid uniform heating, microwave radiation is an efficient source of heat. However, the mechanisms of hydrate decomposition under depressurization combined microwave stimulation are currently unclear. In this study, methane hydrate was synthesized under 6 MPa and 2 degrees C, with hydrate saturation of approximately 42% in natural quartz sand. We then compared hydrate decomposition via rapid depressurization and piecewise depressurization, with or without microwave stimulation at 2.45 GHz and 400 W. When using the depressurization method alone, the hydrate decomposition rate increased with the depressurization amplitude. However, in the last stage of hydrate decomposition, the external flow of gas was hindered by the Jamin effect, especially under larger depressurization amplitudes; therefore, extremely low production pressure is not justified. When combined with microwave stimulation, both depressurization methods resulted in increased reservoir temperature within a few seconds, and microwave heating provided an extra driving force for hydrate decomposition. Furthermore, microwave heating was more effective when larger amounts of undecomposed hydrate remained after depressurization. When depressurization was combined with microwave stimulation, the average gas production rate at 100% gas production was 0.269-0.601 L/min, which was significantly higher than that for depressurization alone. However, the energy efficiency ratio was approximately 1, which has no practical value. Conversely, the average gas production rate at 90% gas production was 0.452-2.945 L/min and the energy efficiency ratio was 2.9-17.6. Under the combined method, gas hydrate decomposition at a production pressure of 1.9 MPa achieved the subtle balance between the average gas generation rate and energy efficiency. Thus, optimizing the gas production pressure and microwave stimulation time can improve the average gas production rate and energy efficiency ratio according to the reservoir hydrate conditions.

Purpose. Geomechanical substantiation of the parameters for conducting stope operations, ensuring the operational state of main workings. Methodology. The research is performed using an algorithm which includes the sequential execution of interrelated stages: analysis of mining-geological and mining-technical conditions for maintaining the network of main workings; mine observations of their state with the identification of specifics of rock pressure manifestations and predicting the probable negative consequences of conducting stope operations in the immediate vicinity; preliminary substantiation of possible technological options for mining the coal seam, taking into account the preservation of operational state of main workings. Scientific calculations for determining the most expedient option are based on the development of geomechanical models of the rock mass behavior around the main workings when mining the adjacent extraction site; analysis of the mass stress-strain state with the prediction of probable rock pressure manifestations; development of recommendations for limiting (or completely eliminating) the negative consequences of conducting stope operations near main workings. The above algorithm of actions uses a combination of experimental mine research methods with technologies for performing computational experiments based on the finite element method. Findings. A systematic analysis of the mining-geological and mining-technical conditions for maintaining the network of main workings has been performed, the results of which are used to substantiate ideas about the mechanism for the occurrence of specifics of rock pressure manifestations, recorded during instrumental observations of their state. Three options have been developed for completing the mining of the extraction site adjacent to the mine horizon main workings. For each of them, a geomechanical model has been constructed for calculating the stress-strain state of the adjacent coal-bearing mass. Its analysis makes it possible to formulate a number of recommendations regarding the rational parameters for conducting stope operations, as well as structural and technological solutions to increase the stability of the main workings and maintain the conditions for their safe operation. Originality. New dependences of influence of the extraction sites on the main working network stability depending on the texture and mechanical properties of lithotypes have been obtained based on the research on the stress-strain state of a weakly metamorphosed mass. For the first time, geomechanical models have been developed of the mutual influence of main workings on the parameters for conducting stope operations. Practical value. The presented recommendations simultaneously reduce the loss of coal reserves and preserve the network of main workings in proper operational state.