Serhii Skipochka’s research while affiliated with National Academy of Sciences of Ukraine and other places

Traditional visual examination technique has many disadvantages when applied to deep open-pit mines with the in-pit crushing and conveying mining technology. In this research, the shortcomings of visual examination are eliminated by supplemental instrumental control and technical diagnostics. To assess the technical state of all types of support, corrosion of equipment and interaction of support with rock massif, vibroacoustic and ultrasonic non-destructive testing methods were adapted. For their implementation in underground structures modern equipment was developed. Testing and implementation was carried out at the ArcelorMittal Kriviy Rih. When examining transport mine workings, a large number of defects were discovered that were not identified by traditional inspection. Such dangerous defects include hidden zones of layers separation, areas of loss of strength of concrete, shotcrete and rock bolts, areas of deep corrosion of metal elements. Based on the results of the examination, the categories of state of mine workings were adjusted, recommendations on methods and timing of repair and restoration measures were developed. This made it possible to significantly improve the safety of miners and prevent the occurrence of emergency situations. The development is recommended for implementation at all deep open-pit mines with the in-pit crushing and conveying technology system.

A comprehensive methodology is proposed and the results of the technical examination of hydraulic tunnels are given. The technique takes into account the influence of water flow, the formation of cavities behind the shell, fixes defects, and reveals the prerequisites for their formation. It consists of visual inspection and non-destructive testing (ultrasonic, electromagnetic, vibro-acoustic). A unified presentation of the examination results is proposed. The optimal basis and operating frequency of the ultrasonic method are substantiated. The gradations of the processes of the formation of cracks in concrete are determined by the frequency of electromagnetic radiation. Examples of tunnel examination are given. Characteristic areas of the objects are identified. For main canals, this is a shell near the entrance and exit portals. Cavities behind the shell can be traced along the entire length of the tunnels. The main defect of the shells of pressure tunnels of power plants is cracks in the reinforced concrete lining. For structures of seasonal drainage, filtration in the bottom is characteristic. The examination results are used to develop projects for repair works. Some methodical regulations can be used for inspecting any underground structures.

The purpose of the work is to perform an analysis of the world experience of multi-purpose use of underground structures and to provide recommendations on monitoring the technical condition and technology of repair and restoration works of underground and buried dual-use objects for their operation in the conditions of Ukrainian realities. The main areas of use of underground structures for additional purposes are considered. In particular, for the equipment of warehouses, isothermal factories, specialized research laboratories, medical institutions with special conditions, tourist facilities. Under martial law, underground facilities are also used to shelter civilians, organize the production of defense products, hold mass cultural events, and create first aid stations for victims. There are two main categories of dual-use underground structures. The first one includes mining workings in the abandoned areas of mines. The main requirements for the workings are a large cross-section, satisfactory natural stability, the absence of harmful gases in the mine atmosphere, and the absence of the threat of flooding. It is desirable to be able to drive vehicles from the earth's surface directly to the required object. These requirements are implemented mainly in mines for the extraction of non-metallic building materials. The second category includes underground hydraulic structures, transport tunnels, basements of industrial enterprises and residential buildings. The main requirements for the performance of additional functions are the provision of full operation of the building for its primary purpose and the creation of safe conditions for people without special knowledge and skills. To assess the possibility of expanding the operational capabilities of underground structures, a methodology for their survey has been developed. The methodology involves a visual assessment of the state of rock exposures and fasteners, determination of the strength of rocks and concrete mainly using non-destructive control methods, detection of cavities behind the shell of an underground structure using the vibroacoustic method. In some cases, control drilling is performed. The presence of people without personal protective equipment in the dual-use underground structure places higher requirements on the stability of structures. To increase the stability of the mine workings, additional fixing of the roof of the workings with anchors, application of shotcrete on rock outcrops and the surface of the destroyed support, creation of canopies in areas where people are concentrated are provided. Increasing the stability of underground structures, which are not related to the extraction of minerals, is achieved by strengthening and installing additional load-bearing structures. To improve the waterproofing of the underground structure, it is recommended to fill the cavities behind the shell, eliminate filtering fractures, repair the seams between the sections of support, and apply a penetrating coating.

Annotation The concept of risk-based technical solutions for the protection of coal mines workings is outlined. The initial data of effective risk management methods are substantiated. A mixed method of risks assessment has been used. The method involves building a matrix of consequences and probabilities by ranking them in the form of tables. The following data have been used as initial data: location, method and parameters of the workings protection, additional measures to manage the state of the rock mass around the workings, cost of certain types of work and material costs, purpose and term operation of the workings. Technical solutions for the protection of underground workings in coal mines to increase labor safety and reduce environmental and financial risks are substantiated. Initial data for effective methods of risks management in the protection of workings in difficult mining and technical conditions have been prepared. It is recommended to use these data as the basis of the new regulatory framework.

The main use of concrete lining is mine and hydraulic engineering construction. The options of its use in underground structures and mining operations have been considered. The advantages of this lining during construction and operation have been reflected. A long service life of underground facilities with concrete lining in Ukraine has been noted. The typical defect types have been identified. The main reasons for defect formation have been reflected. The impact of natural factors on the deterioration of the lining has been researched. The possible consequences of the flaw growth have been reported. Limited opportunities for visual inspection of the concrete surface have been noted. The main areas of non-destructive test of linings have been analyzed. The basic set of methods and control devices have been established. Special features of monitoring with various methods have been indicated. The main requirements for the registration of primary data have been defined. Typical options of office data processing have been outlined. According to the processing results, the category of the technical condition of the lining is determined. Criteria for assessing the technical condition have been presented. Specific examples of complex examination of concrete lining have been provided.

In this work, subject of the research is a method of non-destructive vibroacoustic control of underground structures support. The purpose of the research was to create a methodology and apparatus for vibroacoustic control of the state of the system "support – rock massif" with a wide range of use. The main types of objects where the use of this method is appropriate are determined. Negative influence of external factors on performance characteristics of support is shown. A basic type of support for underground objects is reinforced concrete. It is established that the most characteristic defects are formation of cavities in geological environment behind the support and broken connection of separate segments of the support. The influence of these defects on character of free oscillations of support elements at single shock action was studied theoretically. It is established that the following parameters can be informative for detecting these defects: amplitude characteristic of package of vibration, its duration and spectral composition. Information about the means of vibroacoustic control designed by the Institute with participation of the authors is provided. The methodical features of using vibroacoustic control for assessing technical state of different types of support are considered. The limitations for using the method are explained. Some results of the use of vibroacoustic control of support in underground objects of the various purposes are given.

The subject of the research was physical and mechanical properties of rocks from uranium deposits in Ukraine. The purpose of the work was to study the strength characteristics and features of deformation of rocks of uranium deposits beyond their strength limit to ensure the stability of mine workings at great depths. Research methods were experimental with using stationary laboratory equipment and special recording equipment. The studies were carried out within and beyond the strength limits. The rock specimens were made of material taken from a uranium mine. The complex of the studies included determination of general physical properties of rocks (density, specific gravity, porosity, humidity and adhesion coefficient); basic strength parameters (compressive and tensile resistance depending on humidity and layering, angle of internal friction, elastic modulus, Poisson's ratio, modulus of decrease and residual strength) and deformation characteristics. Calculations of the scale strength factor were made. The results were analyzed. It is shown that the rocks of uranium deposits in Ukraine are considered strong and very strong, according to the Protodyakonov scale. However, structural and textural features lead to the occurrence of a scale effect of strength of rocks. The complex structure of uranium deposits, the steep angle of dip of the rocks, their lamination, as well as the significant size of the mine workings further reduce the strength of the massif. It is also shown that when calculating stability of mine workings and choosing parameters for their support, the strength of rocks in the massif should be reduced by half from the value obtained by standard laboratory tests. The characteristics of rock samples within and beyond their strength limit indicate that they have almost no plastic properties. The ratio of the modulus of decrease to the static elastic modulus for all studied types of rocks of uranium deposits is greater than one. This indicates the tendency of rocks to accumulate potential energy and cause brittle failure of the massif beyond its compressive strength. That is, at great depths, the main problems in mine workings associated with rock deformation processes will manifest themselves in the form of rock bumps, collapses or other dynamic phenomena. This does not exclude the possibility of deformation or destruction of rock support due to static loads. Keywords: uranium deposit, rock, laboratory research, extreme stress, physical properties, strength, elasticity, scale factor.

The subject of the research presented in the article is the fastening and protection of mine workings for the extraction of ore and non-ore minerals for the construction industry. The purpose of the work is the development of the concept of risk-oriented technical and technological solutions for the protection of underground mine workings to dramatically increase the efficiency and safety of extraction of ore and non-ore minerals at deposits of a complex structure. The work uses the well-known mixed method of risk assessment, which assumes that underground mining production is accompanied by three main interrelated indicators: occupational safety of miners, environmental safety, and financial and economic risks. The method involves building a matrix of consequences and probabilities by ranking them. The technical-technological solutions for fastening and protection of workings of iron ore and uranium mines and underground enterprises for the extraction of non-metallic raw materials are analyzed. Their shortcomings are identified and the associated risks of operation and long-term preservation of underground enterprises are assessed. The concept of technical and technological solutions for improving the safety, environmental and economic performance of mines is proposed, which should be the basis of the new regulatory and technical documentation for the protection of workings. In particular, for ore mines, this concerns the transition to new technologies of anchorage, special conditions for lining junctions, introduction of bookmarks in particularly dangerous areas, control and reduction of water inflows. For mines producing non-metallic raw materials, the effectiveness of a complete transition from drilling and blasting technology to a mining machinermed one has been practically. If there are thick seams, it is recommended to work them out in separate layers, leaving a gap between them. It is advisable to divide the zones of geological disturbances into small areas, which are outlined with barrier pillars. Emphasis is placed on the mandatory implementation of comprehensive monitoring of the condition of the roof of the structures and their lining on the active and decommissioned areas. Depending on the degree of risk of collapse in large-scale mine workings and its impact on ground objects, the feasibility of using stowing is determined. Research results can be used to implement measures to improve miners' labor safety, environmental safety, and economic performance of ore and non-ore mines.

The subject of research presented in the article are processes that take into account the influence of geomechanical factors on the stability of mining workings of uranium mines. The purpose of this work is development of a system for ranking geomechanical factors by the degree of danger based on the analysis of risk factors that affect the stability of uranium mines. The work uses critical analysis and generalization of both own research results and the results of domestic and foreign authors. The geomechanical factors that affect the stability of the mining workings of uranium mines have been determined. It is shown that their influence has both a direct and an indirect effects due to the connection with mining-geological and technological parameters. The stability of the workings is significantly influenced by mining and technical factors (outcropping time, working space length, floor height, compression properties and structure of the backfill mass, chamber width, dynamics of cleaning works progress), mining and geological factors (depth of mining, thickness of the ore body, strength (deformation)) and physical and mechanical properties of the rock mass. In addition, the engineering and technical conditions of mine construction have a significant impact, in particular, the form and size of the workings, their orientation in the massif, the method of carrying out and supporting, the design and technology of fastening, etc. It is practically impossible to simultaneously take into account all factors in an analytical way, so it is necessary to select one or two main factors that are of decisive importance for the description of a specific geomechanical process. The originality of the work is the proposed ranking of geomechanical factors that affect the stability of mining workings of uranium mines. The ranking of geological, physical and mechanical factors on the stability of the chamber system elements at underground mining of uranium ores, according to the degree of attenuation of the influence, is as follows: strength of rocks → structure of the massif → angle of fall of the deposit → water content of the deposit → thickness of a seam. The ranking of the influence of support preparatory and capital workings on their stability, according to the degree of risk decrease, is as follows: no support → grid with anchors → sprayed concrete → wooden support → metal frame support with tightening → metal arches in concrete. Generalized ranking of the influence of the most significant factors on the stability of mining workings: geological, physical and mechanical factors → parameters of the development system → fastening technologies.

The aim of the work is to estimate the quantities of methane contained in a coal seam as a solid coal-methane solution and adsorbed inside cracks and pores. The work uses an analytical research method based on the fundamental laws of gas and thermodynamics, as well as physical chemistry. The binding energy in the calculations is taken as averaged over the polymolecular adsorption layer. The Langmuir model to describe the process is used. It was found that the maximum possible total content of methane main phase components does not exceed 70-80 m ³ /ton of coal. This is significantly less than the volumes of methane that is released in the mine during the gas-dynamic phenomenon. It is concluded that a more accurate idea of the gas-dynamic and other anomalous phenomena that take place in the “coal-methane” system can be obtained only by studying its structure at the atomic-molecular level. It is also necessary to take into account the accompanying physicochemical processes arising at the stage of metamorphism and technogenic interference in the coal seam. The work is aimed at improving the theory of gas-dynamic phenomena for the effective prevention of dynamic manifestations of rock pressure in mine workings.