Mine Shafts Research Articles

Understanding the influence of stratification for mine water management: a comparative study

Managing mine water in the best possible way is of great importance and depends on various factors like environmental protection, regulatory compliance and human health. To understand the complex chemical and hydrodynamic processes within the mine pool, it is critical to establish effective practices and management strategies. This study focuses on the characterisation of hydrodynamic processes affecting flooded underground mines, emphasising the importance of density stratification. The investigation of 29 ore and coal mine shafts and their corresponding physico-chemical depth profile measurements was aimed to compare the profiles with each other, while also taking into account the shaft geometry and the layout of the mine. Finding cross-links between the profiles, which allow universal statements on stratification in flooded underground mines, was the main objective. Results of this study indicate that stratification occurs in almost all flooded underground mines, and the uppermost stratified water body is usually located in the area of the first or second connected level. Furthermore, stratification is often responsible for considerably better quality of the uppermost water body. Hence, stratification is fundamental to mine water management and has a direct influence on the quality of the discharged water. This knowledge is invaluable in developing strategies to optimise mine closure, mine water management, treatment planning and future mine layouts.

Use of spatial analysis in the mining field in the Udorka Valley. Introduction to geoarchaeological search for flint workshops at site 24 in Poręba Dzierżna (Małopolska Province, southern Poland)

The prehistoric chocolate flint mine in the Udorka Valley (site 24 in Poręba Dzierżna, Lesser Poland Voivodeship, southern Poland) has been under excavation since 2018. It is the first mine of this raw material discovered outside the Świętokrzyskie Mountains. The currently available dating indicates that the mine was used in the Mesolithic and Neolithic periods.Spatial analysis of artifacts from the fill of the mine shaft allowed for the reconstruction of individual phases of its formation. It also questioned the issue of homogeneity of the assemblage of artifacts from this mining facility and from the overlying layers. Although they are of the workshop type, their simultaneity should be doubted. In order to establish the chronological and cultural framework of flint production in the mining field, it seems necessary to determine the original location of the workshop, which was destroyed and washed out as a result of some kind of runoff. This flow created the sediment that now lies above the shafts, and which is extremely rich in flint artifacts.

Experimental Study on the Strength Characteristics of Cast-In-Situ Mortar Specimens in a Slurry Environment

As coal resource development progresses deeper underground, the increasing depth of mine shafts poses significant challenges to the safety and stability of traditional shaft construction methods, further compounding operational difficulties. In this context, cast-in-situ concrete shaft walls in a slurry environment have emerged as an effective solution. The strength of these shaft walls is a crucial parameter for assessing their safety. To explore this, experiments were conducted on slurry preparation and mortar casting (used here as a substitute for concrete) under three different conditions: slurry environment, pure water environment, and dry environment. The cast specimens underwent compressive, tensile, shear, and microscopic observation tests to analyze the strength development patterns of the mortar specimens in these varied casting environments. The study yielded several key findings: As the casting environment becomes more complex, the strength of the mortar specimens gradually decreases. Specifically, specimens cast in a slurry environment exhibit strengths approximately 15% to 20% lower than those cast in a dry environment, although both environments show similar trends in strength development over time. Across all casting environments, the initial strength loss of the specimens is significant, while the rate of strength loss decreases in the later stages; the strength loss is minimal in specimens cast in a pure water environment and reaches its maximum in those cast in a slurry environment. Additionally, in specimens cast in a slurry environment, air void diameter tends to polarize, and the distribution of air void is denser compared to the other two environments. In conclusion, cast-in-situ mortar in a slurry environment exhibits the lowest strength and the greatest strength loss compared to specimens cast in dry and pure water environments. Nonetheless, the strength development trends over time remain similar across all conditions, providing theoretical and technical support for the construction of shaft walls in slurry environments.

Prospects of concrete lining in mine shafts in salt rocks

Prospects of concrete lining in mine shafts in salt rocks

Study on the flow field of multi-phase coupling slag discharge and the influencing factors of slag discharge effect in gas lift reverse circulation of drilling shaft sinking

Combined with the advanced drilling of the central return air shaft in Kekegai Coal Mine, the distribution law of slag discharge flow field by drilling method and the influencing factors of slag discharge effect are studied. Firstly, the numerical model of gas–liquid–solid coupling slag discharge is established by CFD-DEM (computational fluid dynamics coupled discrete element method). Then, the flow field distribution law of the site slag outlet layout model and the optimization model is compared and analyzed. Finally, the influence of drilling parameters on slag discharge effect is studied. The results show that the best arrangement of slag suction ports is: the number is two, the length-diameter ratio is 0.4, the area ratio is 1, and the total area ratio is 1.94%. The fluid movement at the bottom of the well is mainly tangential flow, while the fluid in the slag discharge pipe is mainly axial flow. The construction parameters of efficient slag discharge are put forward: bit rotation speed is 8.7 r/min, gas injection rate is 4200 m3/h, air duct sinking ratio is 0.84, and mud viscosity is 165 MPa·s. The research results can provide useful theoretical reference for large-scale sinking construction in deep wells.

Land Use Legacy Landforms at the UNESCO Heritage Site Tarnowskie Góry, Upper Silesia, Poland—Stratigraphy, Soils and Age

ABSTRACTMetallurgy in Upper Silesia (Poland) has a long tradition of international significance, which was emphasized in 2017 when the historic silver mine in Tarnowskie Góry was inscribed as a UNESCO World Heritage site. The area consists of various anthropogenic landforms, the stratigraphy of which has hardly been studied so far. In this study, we describe five main morphological units: Unit I (RCH) and Unit II (RCH pit), resulting from charcoal production; Unit III (shaft) and Unit IV (shaft heap), resulting from mining; and Unit V (reference forest soil). The first four units are a variation of a Technosol with inherently different properties from the reference forest soil. Unit I exhibits typical properties of a relict charcoal hearth (RCH), whereas Unit II resembles a pit. Unit III consists of a mostly infilled mining shaft remain (MSR), characterized by relocated subsoil. Unit IV consists of material from the adjacent Unit III that has been dumped directly aside. The studied RCH was used no earlier than during the second half of the 17th century, probably between 1725 and 1813. The studied MSR was used most likely between the 3rd and 5th centuries, which is much older than described so far. Together, the units reflect the characteristic heterogeneity of soils in shaft mining and RCH areas.

A New Self-Sensing Fiber Optic Anchor to Monitor Bolt Axial Force and Identify Loose Zones in the Surrounding Rock of Open TBM Tunnels.

TBM has been widely used in underground engineering and construction, but there is no precedent for the application of open TBM in the inclined shafts of coal mines, which brings new challenges to the support system. The distribution of the axial forces on anchors and the range of loosening of the surrounding rock are crucial considerations in tunnel support design. Existing methods for measuring the axial forces in anchors and determining the extent of loosening in the surrounding rock typically remain at the inspection level, lacking long-term and real-time monitoring capabilities. This paper presents a new self-sensing anchor with embedded optical fibers (made using an improved stirrer) and proposes an intelligent tunnel rock monitoring system. The paper also outlines a method for identifying loosening zones in surrounding rock based on monitoring data and theoretical analysis. Installing self-sensing anchors in the deep sections of the rock surrounding a tunnel provides three-dimensional, round-the-clock real-time monitoring of the axial forces acting on the anchors, using new technology and methods to recognize the deformation characteristics of loosening zones within the surrounding rock. This new self-sensing fiber optic anchor was first applied to an open TBM tunneling project in an inclined shaft in the Kekegai coal mine, and monitoring data indicate that self-sensing optical fiber anchors can accurately reflect stress patterns in real time. The axial force curve can be divided into four segments: the borehole area, the loosening zone, the stable zone, and the anchoring zone. Consequently, it accurately identifies the thickness of loosening zones at different positions within the tunnel's surrounding rock. This information is compared and verified against results obtained from bolt dynamometers and borehole inspection. On this basis, an intelligent monitoring system was established to provide a basis for making engineering construction decisions, which makes tunnel construction smarter and helps technicians timely adjust TBM driving and support parameters.

Going Underground: The Author’s Body and the Mining Workplace in the Writing about Miners in Modern China

Abstract This article highlights the author’s body and its physical experience in labor history, by a focus on their historical implication for the emergence of writings about miners in late-nineteenth- and early-twentieth century China. Miners and their workplace entered Chinese textual and pictorial representations at the turn of the twentieth century, as a result of the growing importance of the mining industry, the dissemination of new mining knowledge, and the formation of new social groups. Later in the 1920s, literary movements tied up with the revolutionary agenda under the influence of Marxism brought new conceptualizations of miners’ position in society and their relationship with intellectuals. When authors turned to write about miners in the late 1920s and early 1930s, they chose to legitimize their writing by descending into mine shafts to acquire the experience in the underground mining workplace and to incorporate the bodily experience into their writings. The mining lamp in texts and images from this period provides a prime example to illustrate how the author’s experience in the underground mine was embodied in the author’s and the miner’s corporeal visions and contributed a new way of seeing and representing miners. Drawing upon materials about miners of various genres, this article reveals the formulation of Chinese visual modernity within Chinese social interactions and brings the author’s body into labor history by calling attention to both its material presence in the workplace and its agentic power to inscribe workers.

Sporothrix and Sporotrichosis: A South African Perspective on a Growing Global Health Threat.

Sporotrichosis is a disease that arises from a fungal infection caused by members of the Ascomycete genus Sporothrix. The disease has a unique history in South Africa, due to an association with gold mines, where large numbers of mine workers were infected in the 1930s and 1940s. This was likely driven by hot humid conditions and timber supports used in these mine shafts. Furthermore, the disease is the most common subcutaneous fungal infection amongst the general population in South Africa, and the large number of immunocompromised individuals increases the public health risk in the country. Sporothrix is a genus in the Ophiostomatales, a fungal order primarily associated with environmental habitats. Unsurprisingly, sporotrichosis therefore has a documented history of sapronotic transmission from contaminated plant material. This review provides insights into the understanding of sporotrichosis and Sporothrix species, with a particular emphasis on the South African situation. We highlight knowledge gaps, particularly regarding the ecological factors influencing the occurrence and distribution of these species, which in turn affect the patterns of sporotrichosis. We also emphasise a need for ongoing proactive research and surveillance to prevent future outbreaks of sporotrichosis, an emerging disease with growing health implications worldwide.

Chemical elements migration in underground waters of mining territory

Relevance. The need to study the forms of migration of chemical elements in the groundwater of flooded copper pyrite mines in order to correctly understand and predict their transfer and distribution in hydrogeochemical fields. Ground and surface waters are a complex mixture of substances in which, depending on pH, Eh and t °С, phase transitions are formed with subsequent dissolution or precipitation of minerals. To solve these problems, numerical hydrogeomigration modeling is used, including physicochemical, which allows drawing conclusions about the scale of pollution and the localization of such areas for subsequent development of measures to improve the state of the hydrosphere. Aim. To determine the forms of metal migration in groundwater and to calculate water saturation indices in relation to minerals. Objects. Groundwater in the territory of the closed Levikha copper pyrite mine. Methods. Laboratory studies of groundwater were carried out using flame emission spectrometry, flame atomic absorption, photometric method with Nessler's reagent, titrimetric, mercumetric and potentiometric methods; mass spectrometry with ionization in inductively coupled plasma and gravimetric method. Physical and chemical modeling using the software product Visual MINTEQ 3.1. Results. According to the results of processing chemical analyzes and physical and chemical modeling, all tested wells are divided into groups: 1) wells no. 1, 2, 3 and 6, located within the former mining allotment (near the Levikha XIV mine, a man-made reservoir, the Levikha II mine and a neutralization station); 2) represented by water in wells no. 4 near the shaft of the mine Tsentralnaya and no. 5 near the dump Yuzhny; 3) well no. 7, located near the mouth of the Levikha river. Saturation indices and forms of migration of components in the aquatic environment make it possible to identify the scale of pollution and the localization of such areas. Thus, with the current pumping system, there is no large-scale pollution of groundwater at the Levikha mine. It is localized in the area of the Tsentralny mine shaft (well no. 4) and the Yuzhny dump (well no. 5).

Hellfire Exploration: the origins of ground source heat in early mining technology

The ground source heat pump (GSHP) was first used in 1862, for freezing ground in connection with sinking a shaft in Swansea, UK. It was subsequently developed in Germany in 1882-83 into the “Poetsch process” for freezing ground during construction of mine shafts. The Poetsch process was an indirect closed loop GSHP system, circulating a chilled brine from a heat pump around a network of coaxial borehole heat exchangers. These early systems typically employed ammonia as a refrigerant and a calcium or magnesium chloride solution as the brine. Such a system was used in 1904-1906 to sink the shafts of Dawdon Colliery, Co. Durham, UK through water-bearing Permian strata. Also, around 1904, the Newcastle-based turbine pioneer, Charles Parsons, suggested that such a GSHP system could transport heat to the surface during the construction of a 12 mile deep “Hellfire Exploration” shaft, that could potentially access geothermal power.

Management of Mining Brownfields for Support of Regional Tourism

Turbulent political and economic changes in 1989 caused the gradual decline of the mining industry in the Slovak Republic. Abandoned territorial localities were created, affected by mining activity, without any use with devastated mining objects, or even a certain form of environmental burden. These territorial locations used for mining in the past, unused currently, in varying degrees of devastation, are referred to as mining brownfields. This issue is topical, as there is constant urbanization of new territories. Mining brownfields often represent a certain form of territorial reserve to support tourism development. The present study deals with identifying the tourist potential of the Fedö shaft mining brownfield in the Červenica—Dubník area (Slovakia), which is included in the list of national cultural monuments. The study points out the need for reclamation from the point of view of supporting the development of a tourist destination based on the accessible mining brownfield—the Jozef tunnel—making it possible to use the interaction links of both mining brownfields in the investigated area of tourism. Based on the results of the conducted SWOT analysis, the study presents the quantification of the tourism development support potential of the analyzed mining brownfield. It also includes selected environmental, social, and economic aspects of the reclamation, and the definition of an effective strategy for usage of the examined mining brownfield as a tool to support tourism development. The article concludes a model of effective management of the use of mining brownfields in the field of tourism in Slovakia, which is constructed as open and modifiable in its interaction with the specification of diverse conditions of tourist destinations with integrated mining brownfields, which include old mine works.

Experimental studies of the generating capabilities of mine hoists in industrial conditions

The article is devoted to a topical subject of distributed generation of electrical energy. The cage and skip mine hoists of the iron ore mining enterprise were considered as generators of electrical energy. The purpose of the study is to compare theoretical and experimental data on electricity generation by mine hoisting units of the Sukha Balka PJSK (Kryvyi Rih, Ukraine). The research methods are theoretical ones – on the transformation of the potential energy of a solid body into electrical energy during its movement through a mine shaft, and experimental ones – involving instrumental measurements of the consumption and generation of electrical energy by cage and skip hoists units during industrial operation. Research schedule: collection and processing of information on the operation of the cage and skip hoists of the mine named after Frunze and similar indicators of the cage and skip hoists units of the Yuvileyna mine for the period from September 1 to December 31, 2021. The novelty of the research lies in the instrumental measurement of the electrical parameters of mine hoists in real Ukrainian operating conditions. The most significant results: it was found that the volumes of electricity generation by mine cage hoists significantly exceed the results of skip hoists. The actual indicators of electricity generation by cage hoists units are much lower than the results of theoretical estimates. There is an imbalance between the generation and consumption of energy resources – 9% for the cage elevation of the mine Frunze; about 2% for the cage hoist of the Yuvileyna mine; less than 1% on skip units. It was found that there is a statistically significant correlative relationship between the generation and consumption of electricity by the cage hoist of the mine named after Frunze and no statistically significant relationship between the generation and consumption of electricity by the cage hoist unit of the Yuvileyna mine. The electricity obtained from the daily operation of two cage and two skip units of the Sukha Balka PJSC (approximately 400 kWh) is enough to power 58 average Ukrainian households.

DRA-UNet for Coal Mining Ground Surface Crack Delineation with UAV High-Resolution Images.

Coal mining in the Loess Plateau can very easily generate ground cracks, and these cracks can immediately result in ventilation trouble under the mine shaft, runoff disturbance, and vegetation destruction. Advanced UAV (Unmanned Aerial Vehicle) high-resolution mapping and DL (Deep Learning) are introduced as the key methods to quickly delineate coal mining ground surface cracks for disaster prevention. Firstly, the dataset named the Ground Cracks of Coal Mining Area Unmanned Aerial Vehicle (GCCMA-UAV) is built, with a ground resolution of 3 cm, which is suitable to make a 1:500 thematic map of the ground crack. This GCCMA-UAV dataset includes 6280 images of ground cracks, and the size of the imagery is 256 × 256 pixels. Secondly, the DRA-UNet model is built effectively for coal mining ground surface crack delineation. This DRA-UNet model is an improved UNet DL model, which mainly includes the DAM (Dual Dttention Dechanism) module, the RN (residual network) module, and the ASPP (Atrous Spatial Pyramid Pooling) module. The DRA-UNet model shows the highest recall rate of 77.29% when the DRA-UNet was compared with other similar DL models, such as DeepLabV3+, SegNet, PSPNet, and so on. DRA-UNet also has other relatively reliable indicators; the precision rate is 84.92% and the F1 score is 78.87%. Finally, DRA-UNet is applied to delineate cracks on a DOM (Digital Orthophoto Map) of 3 km2 in the mining workface area, with a ground resolution of 3 cm. There were 4903 cracks that were delineated from the DOM in the Huojitu Coal Mine Shaft. This DRA-UNet model effectively improves the efficiency of crack delineation.

Numerical Modeling the Rock Mass Stress-Strain State Near Vertical Excavations in Combined Mining

In recent years, the development of the mining industry in the Republic of Kazakhstan has been accompanied by the commissioning of new underground levels for many existing mineral deposits, which were initially developed through open-pit mining. As the depth of open-pit mining increases, the volume of overburden rises sharply, making open-pit mining unprofitable due to the significant amount of additional mining work required. For this reason, most open-pit mines in Kazakhstan are transitioning to underground mining, or combined mining. Many researchers have examined the timing of this transition and have worked on optimizing it to determine the best economic efficiency and manage risks. However, there is limited information available on how to determine the optimal location for a vertical mine shaft when transitioning from open-pit to underground mining. The purpose of this study is to identify a safe location for a vertical shaft in combined mining operations. Specifically, the study assesses the impact of the open-pit mine on the selection of the mine shaft’s location, considering the stress-strain state of the rock mass during combined mining methods. To address these objectives, numerical modeling of the stress-strain state around vertical excavations during combined mining was performed. The results provide a solution to the critical issue of determining the location of the mine shaft in combined geotechnology and lay the groundwork for further research on shaft placement in Kazakhstan. The novelty of this study lies in identifying the shaft location by considering the geometric shape of the open-pit mine and the depth of development. Doi: 10.28991/CEJ-2024-010-09-010 Full Text: PDF

Impact of corrosion of cast iron tubing on residual strength of mine shaft lining

Impact of corrosion of cast iron tubing on residual strength of mine shaft lining

The Influence of Grain Size Gradation on Deformation and the Void Structure Evolution Mechanism of Broken Rock Mass in the Goaf

The high porosity and high specific surface area of the broken rock mass in abandoned mine goaf make it an excellent thermal storage space. The void structure is an important factor that affects the permeability characteristics of broken rock mass, which determines the efficiency of extracting geothermal water from abandoned mine shafts. To accurately describe the void structure of broken rock mass, the effect of particle erosion on the fracture of rock blocks is considered in this study, based on which an impact-induced strength corrosion calculation model was proposed. Then, this calculation model was embedded into the three-dimensional numerical simulation of broken rock mass for secondary development. A discrete element numerical calculation model was established for broken rock masses with different size grading distributions under water immersion and lateral compression conditions. On this basis, considering the strength erosion effect of impacts, this study investigated the deformation and fracture characteristics of broken rock masses with different size grading distributions and analyzed the evolution laws of porosity in the broken rock masses. The main findings are as follows: The impact effect has a significant influence on the growth of microcracks and the breakage rate of broken rock mass. When the particle size of the broken rock mass differs significantly (size grading as G3), impact-induced strength erosion exerts the greatest impact on the growth of microcracks and the breakage rate. When the particle size of the broken rock mass is uniform (size grading as G1), impact-induced strength erosion minimally impacts the secondary fracturing of the broken rock mass. When the strain of the broken rock sample is less than 0.175, the distribution of microcracks is scattered; when the strain reaches 0.275, microcrack propagation accelerates and exhibits a clustered distribution; and when the strain reaches 0.375, microcracks exhibit a reticular distribution and their connectivity is enhanced. With the increase in deformation, the broken rock mass porosity decreases, and the porosity curve fluctuates along the z-axis with a decreasing trend and gradually becomes more uniform. This study provides a theoretical foundation for assessing the efficiency of extracting and storing mine water with heat in abandoned mine geothermal mining projects.

Quality evaluation of surrounding rocks in a mine shaft based on the game gray target model

Accurate evaluation of surrounding rock quality grade can help guarantee the safety of tunnel design and construction; hence, it has great significance in the construction of mine shafts. Accordingly, the uniaxial saturated compressive strength of the rock block Rc, rock quality index RQD, rock softening coefficient kR, integrity coefficient of the rock mass kv, depth H, unit weight of the rock mass γ, coefficient of quantification of the angle between the principal structural plane and shaft axis k2, and weight of the groundwater k1 are first selected as the indexes of assessment to introduce the game gray target model. Then, the gray target model of the surrounding rocks in a mine shaft project is established. The weight coefficient of each index is next calculated using the combination weighting method based on game theory, and the synthetic target center distance of each sample is determined using the gray target model. Finally, the quality level of the asphalt pavement is determined. The suggested model can be used to mine a small data sample to the maximum extent possible, thereby minimizing the information shortage caused by the small sample to a certain extent, to evaluate the final quality grade of the surrounding rocks quantitatively. Thus, the proposed approach provides a new scheme for the future quality assessments of surrounding rocks.

Research of a new multifunctional composition against the corrosion of the internal surface of oil pipelines in the mine shaft

For the first time, a chloroprene reagent (named as Z-1) has been used against corrosion in various aggressive environments under laboratory conditions. The corrosion protection properties of the reagent Z-1 have been studied in formation waters taken from oil wells No. 2646, 33151, 4012, 31193 and 33016 in operation at Balakhani Oil OGED. Samples made of Ct3 and P-105 brand steels with dimensions of 42155 mm have been used during the tests. Experiments have been performed under dynamic conditions at room temperature for six and twenty-four hours, and the corrosion rate has been determined by gravimetric method. During the experiments, concentrations of 10, 15, 20 and 25 mg/l of Z-1 composition were used. The analysis of results from numerous experiments conducted with both types of steel revealed that the optimal concentration of the composition is 25 mg/l. The protection efficiency of the composition Z-1 in the formation waters of the abovementioned oil wells during the six-hour experiment was as follows: for Ct3 samples, it ranged from 75% to 94%, 75% to 97%, 76% to 98%, 72% to 94%, and 68% to 87%, respectively, while for P-105 steel samples, it ranged from 76% to 96%, 72% to 92%, 73% to 85%, 70% to 90%, and 72% to 96%, respectively. During 24-hour corrosion tests, the protection efficiency of the composition Z-1 was 73–92%, 74–96%, 75–97%, 70–92%, and 66–85% for Ct3 steel samples and 75–94%, 70–91%, 72–83%, 68–89%, and 71–95% for P-105 steel samples, respectively.

Analysis of Potential Use of Freezing Boreholes Drilled for an Underground Mine Shaft as Borehole Heat Exchangers for Heat and/or Cooling Applications

Borehole engineering encompasses the part of mining that involves the process of drilling boreholes and their utilization (e.g., for research, exploration, exploitation, and injection purposes). According to legal regulations, mining pits must be closed after their use, and this applies to pits in the form of boreholes as well. The Laboratory of Geoenergetics at AGH University of Krakow is involved in adapting old, exploited and already closed boreholes for energetic purposes. This includes geothermal applications, as well as energy storage in rock formations and boreholes. Geoenergetics is a relatively new concept that combines geothermal energy with energy storage in rock formations (including boreholes). One type of analysed borehole is a freezing borehole. They are used, for example, in drilling mining shafts that are in the vicinity of aquifers and are drilled using the rotary drilling method with a reverse circulation of drilling mud, or in peat bogs. For borehole heat exchangers based on freezing boreholes for long-term mathematical modelling, several heating scenarios were considered with several thermal loads. The maximum average power obtained after one year of usage of four boreholes with variable temperatures was 11 kW. With the usage of 10 boreholes the power reached over 27 kW. The heat-carrying temperature was assumed to be 22 °C during early summer (June and July) and 2 °C during the rest of the year. When considering stable exploitation during a 10-year period with four boreholes with the same temperatures, a heating power of over 12 kW was obtained, as well as a power of over 28 kW when considering using 10 boreholes. The maximum amount of heat obtained during the 10-year period using 10 boreholes was over 8.8 thousand GJ. Once they have fulfilled their function, these boreholes lose their technological significance. In the paper, the concept is outlined, and the results of the analysis are described using the numerical program BoHEx.