Liliia Prokhorets’s scientific contributions

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.

The purpose of this work is to establish the disadvantages and advantages of existing foreign and domestic technological developments for the maintenance of workings in iron ore and uranium mines and to determine the most promising ways to increase their reliability.The analysis of the existing technological developments for the maintenance of uranium and iron ore deposits workings made it possible to establish a variety of options for increasing the operational reliability of potentially dangerous areas. Taking into account these results and the peculiarities of the mining and geological conditions of deposits of iron and uranium ores in Ukraine, studies of the stability of mining workings with the application of various technological solutions have been carried out. As a result of the conducted research, it was proposed: - the use of a rod support based on slag-silicate fast-hardening cartridge mixtures, consisting of a metal rod, a rubber sealing plug and cartridges with fast-hardening mixtures. - the use of contour (smooth-wall) blasting technology during tunneling, which reduces the dynamic impact of blasting on the rock massif and the formation of additional fracture in its near-contour zone. It has been established that in difficult mining and geological conditions, protection of workings should be carried out by combined methods. At the same time, both supports affecting the massif in the near-contour zone of the workings and special supports for specific conditions are used. The general scheme of implementation of such methods is given. Thus, the experience of maintaining workings in difficult mining and geological conditions during underground mining of ore deposits showed the need to continue researching the patterns of deformation and destruction of unstable rocks and creating new technological solutions and supports to solve the problem of maintaining workings and increasing the duration and safety of their operation. The choice of supports for maintenance of workings in specific mining and geological conditions is determined, first of all, by the reliability factor. At the same time, using the existing developments, successfully tested in the underground mining of iron ore, as well as coal and non-mineral raw materials, which allow to increase the reliability and safety of the works, it is necessary to find out the possibility of their application also in the working of uranium mines. Keywords: uranium and iron ore deposits, stability of workings, technological solutions, fastening of workings, support.

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 goal of the paper is to justify ways to achieve maximum radius of extent of grouting mortar in a rock massif and to maximize filling of cavities and cracks with minimal openings. Filling of cavities and cracks directly influences a “massif – roadway – safety structure” system. Some scientific and technical aspects of grouting and injecting inorganic binders into marginal rocks are considered. Advantages of usage of triple plunger pumps in injecting units are determined. The influence of pulsation on a condition and process of grouting mortar extension is justified. It is established that under equal operating conditions, pulsations created by a triple plunger pump reduce mortar viscosity by 15 %, and a radius of extent of mortar based on grouting cements is increased by an average of 12 %, and with usage of very finely dispersed substances – up to 20 %. Suggested recommendations significantly improve the technology of grouting of marginal rocks and concrete structures.

This article shows the possibility of using the shock impulse method widely used in the building industry for the control of above-ground concrete structures in relation to elements of underground geocomposite protective constructions. As a result of experimental studies performed in the laboratory on various mortar mixtures that harden, it was established that there is a close correlation relationship between two data arrays: the values of the shock pulse duration and the uniaxial compression strength. The reliability of the obtained regression equations is in the range of 0.82 - 0.9. This shows the possibility of using the shock pulse method in the new version, with the previously unused informative parameter - the shock pulse duration for assessing the strength of mortar mixes that harden, which are widely used to create geocomposite constructions.

This article summarizes the results of numerous experimental studies of the physicomechanical properties of rocks from deposits of Zakhidnyi Donbas. The analysis of the obtained data allowed us to reveal the zonal nature of their change. Regularity has been established for increasing the strength parameters of rocks in the direction from west to east, the mechanism of which is explained, among other things, by the influence of Coriolis forces arising from the daily rotation of the Earth. It has been established that for more durable rocks, such as sandstone, the change in strength characteristics in the roof and floor is insignificant, whereas for weaker mudstones and siltstones, there is a significant difference in the above strength parameters. A generalization of the test results of Zakhidnyi Donbas rocks showed a large variation in their properties under the conditions of the achieved depth of the reservoir under development, which is due to the variability of the composition, structure, texture of the rocks and the degree of epigenetic transformations.