Water-bearing Rocks Research Articles

Shear mechanical behavior and fracturing path of red sandstone treated by joninted effect of water-fractures

Water content and primary fractures can change the mechanical characteristics of rock, making it easy to induce geological disasters. Therefore, direct shear tests of red sandstone under the action of water-fracture were carried out in this paper. The results show that shear strength of rock samples with fractures is less than that of intact rock samples. With the increase of primary fracture dip angle, shear strength and macroscopic crushing area of the rock sample increases first and then decreases with 20° as the boundary. It shows that the primary fractures weaken the shear mechanical properties and change the macroscopic failure mode. The shear performance of water-bearing rock samples is weaker than that of intact rock samples, and the weakening degree of water-saturated on shear performance of rock samples is lower than that of unsaturated water state. The fracture surfaces of rock samples are divided into 'shortest path single through type', 'longest path single through type' and 'cross path through type'. The failured rock samples are divided into 'single through type' and 'cross through type'. The research results can provide reference for geological disaster management under relevant conditions.

Water Quality of Unconfined Aquifer in Universitas Negeri Malang Following the Drinking Water Quality Standard of Indonesian Ministry of Health

The quality of groundwater is naturally determined by water-bearing rock characteristics. However, the progression of civilian activities also negatively affects the groundwater quality. Therefore, this study aims to assess the physical, chemical, and biological characteristics of groundwater in the Universitas Negeri Malang (UM) campus area in Indonesia and evaluate its compliance with drinking water quality standards, particularly the Class A standard. A comparative descriptive strategy was utilized in the study by involving groundwater in the campus area of UM. The focus of the research is water quality in unconfined aquifer. Through purposive sampling, 12 wells were selected to ensure appropriate spatial dispersion. Water samples were collected in sample bottles and tested for physical, biological, and chemical properties. These water quality tests were carried out in the Perum Jasa Tirta I Malang. Water quality data were analyzed qualitatively, descriptively, and comparatively. This study concludes that (1) the groundwater on the UM campus generally meets the physical criteria for drinking water quality standards; (2) the chemical quality of the groundwater on the UM campus still satisfies the drinking water quality standards; and (3) biologically, the free groundwater on the UM campus fails to meet drinking water quality standards. The novelty of this research is that the biggest threat to the quality of free groundwater in the campus area is bacterial contamination from sanitation activities. Accordingly, it is recommended that groundwater is boiled before being utilized for drinking water purposes to neutralize the E. coli bacteria present in all well water samples.Keywords: Water Quality; Unconfined Aquifer; The Drinking Water; Quality Standard

Engineering geophysical investigations using electrical resistivity tomography for groundwater exploration in the Bodaibo district of the Irkutsk region

Relevance. The need in technical groundwater exploration to construct a groundwater well for water supply of the rotation village of the mining and processing plant "Svetlovsky" in the Bodaibo district of the Irkutsk region. The electrical resistivity tomography is a common method for studying the upper part of a cross section and is widely used in mineral prospecting, geological mapping, engineering surveys, hydrological and environmental studies. The application of electrical resistivity tomography in these conditions will allow substantiating the location of hydrogeological wells and boreholes. Aim. Assessment of the geological and hydrogeological conditions of the area of work for the prospect of extracting groundwater for technical water supply for the needs of the rotational camp. Objects. Bedrocks, which are characterized by high resistance values and are aquicludes; permeable low-resistance zones that are water-bearing rocks. Methods. Ground-based geophysical surveys using electrical resistivity tomography; two-dimensional inversion of ERT data and their interpretation taking into account engineering and geological data of drilling and the GIS complex. As a result of the engineering and hydrogeological surveys performed using ground-based geophysical surveys by electrical resistivity tomography, it was established that the aquifer system of fissured rocks of the Imnyakh suite of the Proterozoic sediment complex (PR2-3im) is represented by fissured limestones of various colours from grey to blueish, with bands of mica schist. Analysis of the study results showed that the thickness of the exposed sediments is up to 50 m, the groundwater level of the operating horizon is opened at depths from 21 to 28 m. They are covered with a complex of low-permeability sediments of thickness from 5 to 11 m that are presented by interbedding of dense grey limestones and black metasandstones.

Numerical investigation of the path-dependent frost heave process in frozen rock under different freezing conditions

Frost heave in water-bearing rock masses poses significant threats to geotechnical engineering. This paper developed a novel three-dimensional (3D) frost model, based on the combined finite-discrete element method (FDEM), to investigate the frost heave process in rock masses where thermal transfer, water migration, water-ice phase transition (ice growth) and ice-rock interaction are explicitly simulated. The proposed model is first validated against existing experimental and analytical solutions, and further applied to investigate path-dependent frost heave behavior under various freezing conditions. Results show that freezing direction plays a vital role in the dynamic ice growth and ice-rock interaction, thus affecting the frost heave behavior. In the top-down freezing regime, ice plugs form first at the crack's top surface, sealing the crack and preventing water migration, which can amplify ice pressure. Parametric studies, including rock Young's modulus, ice-rock friction, and rock hydraulic conductivity, further reveal that the temporal aspects of ice development and rock mechanical response strongly affect ice-rock interaction and hence the frost heave mechanism. Furthermore, some typical phenomena (e.g. water/ice extrusion and frost cracking) can also be well captured in this model. This novel numerical framework sheds new light on frost heave behavior and enriches our understanding of frost heave mechanisms and ice-rock interaction processes within cold environment engineering projects.

Step-path failure mechanism and stability analysis of water-bearing rock slopes based on particle flow simulation

Step-path failure is a typical damage mode of rock slope featuring intermittent joints. In order to investigate the effect of water-fracture interaction on the stepped failure, laboratory experiments of rock materials and numerical simulation of slopes with intermittent joints were conducted. At the laboratory scale, the influence of water-fracture interaction on the mechanical characteristics and acoustic emission response of step-path failure in rocks was examined, and the particle flow model parameters were calibrated for uniaxial testing. At the field scale, the step-path failure process of the rock slope near Longmenqiao reservoir was numerically analyzed using the particle flow method to assess the effects of water and joint distribution on failure. Laboratory findings suggest that compared with dry red sandstone, the average uniaxial compressive strength and average elastic modulus of saturated red sandstone decrease by 35.82% and 23.33%, respectively. The increase in fissure angle in sandstone results in enhanced strength and stiffness, alongside a transition from shear to tension failure mode, with a delayed occurrence of large-scale acoustic emission events. In particular, within the 30°–60° range, the uniaxial compressive strength and elastic modulus of saturated sandstone increase by 66.78% and 29.64%, respectively. The analysis of crack propagation and stress field during slope deformation shows that step-path failure is a progressive process from bottom to top, and revealed the control mechanism of joint and bridge angle on slope stability. The research results enhance the understanding of the step-path failure mechanism and provide important theoretical support for the stability evaluation and landslide monitoring of rock slopes with intermittent joints.

ASSESSMENT OF CHEMICAL POLLUTION OF THE SURFACE WATER IN VLADIMIR

The results of studies of river water of the Vladimir city district for the content of heavy metals conducted in August 2022 are presented and the anionic-cationic composition of water is analyzed. It is shown that a number of heavy metals (lead, iron, cadmium, zinc, copper and vanadium) and ions (ammonium, magnesium, sulfates, nitrates, fluorides, phosphates) in water samples of the rivers of the city district exceed hygienic and fishery standards, which is due to both human economic activity and regional specifics of the geochemical composition of water-bearing rocks and features of groundwater functioning and feeding. The potassium concentration in water of the Nerl river, which is a drinking water source for Vladimir, corresponds to the lower threshold of physiological competence, which can affect the health of city residents if they use such water for a long time. It is shown that insufficient extraction of biogenic elements at the treatment facilities of enterprises could lead to their ingress into water bodies in concentrations exceeding hygienic and fishery standards. This in turn could contribute to the accumulation of other elements. Strict requirements for the content of chemical elements in fishery water bodies make it necessary to improve the equipment and technological schemes of purification at treatment facilities. Small rivers of cities are vulnerable and poorly protected; therefore they require special attention of environmental authorities. Being tributaries of larger rivers, small rivers form the quality of their waters. If they are used for the household and drinking purposes, they become a factor determining the health of urban residents.

Geochemical transformations of sulfur and their role in the formation of different types and subtypes of saline lakes in Southeastern Transbaikalia

This study focused on the chemistry and isotopes of sulfur in lakes. The bottom sediments and water columns of lakes were found to contain reduced forms of sulfur, including hydrogen sulfide ions, elemental sulfur, and thiosulfate ions, along with sulfate ions. It was determined that elemental sulfur in lakes is present mainly in the form of suspensions and colloids, and the proportion of elemental sulfur in polysulfides increases with increasing water pH. It was shown that sulfate reduction results in the greatest isotope fractionation, with a light sulfur isotope accumulating in hydrogen sulfide ions and a heavy sulfur isotope accumulating in sulfate ions. It was confirmed that the abiotic reaction of hydrogen sulfide with oxygen yields a mixture of products that are depleted in 34S and enriched in 34S in hydrogen sulfide. In contrast, the microbial oxidation of HS− → S0 yields zerovalent sulfur, which is 2–4‰ heavier than the initial product. It was shown that the loss of sulfate ions due to bacterial reduction is most significant in subtype-I and subtype-III chloride and soda lakes. In contrast, in subtype-II sulfate and soda lakes, an increase in sulfate ions was noted due to the oxidation of hydrogen sulfides in water-bearing rocks and bacterial hydrogen sulfide. This finding indicated that in addition to evaporation, the formation of a particular type and subtype of saline lake involves the processes of aluminosilicate hydrolysis, sulfate reduction and hydrogen sulfide oxidation.

PECULIARITIES OF THE GROUNDWATER CHEMICAL COMPOSITION WITHIN THE SAKSAGANSK-SURSK ORE DISTRICT OF THE DNIPROPETROVSK REGION

The purpose of the research: to study the groundwaters in the Saksagansk-Sursk ore district of the Dnipropetrovsk region, which are used to ensure the economic and drinking needs of the local population. Data and Methods: A wide range of methods of obtaining, processing and interpreting of ecological-hydrogeochemical data, including field, chemical-analytical, comparative and graphical, were used. Mathematical and statistical methods were used in the processing of the obtained data. Visualization of the general chemical composition was performed with the help of specialized software tool GW_Chart. Results. The chemical composition of underground waters was studied, an assessment of their quality and suitability for potable use was made, the range of risks for the health of local residents-consumers of water was outlined, and the rationale for possible reasons for changes in their chemical composition during 42 years of operation (from 1978 to 2020) was provided. During the research, the authors found signs of metamorphosis of the chemical composition of groundwater. On the other hand, in the multi-year section, a general regularity was observed regarding the restoration of the state of the studied waters resources to the natural one, which is probably related to the decrease in the level of man-made load on the water environment over 42 years due to a significant decline in the rate of industrial development of uranium and iron ores within the Dnipropetrovsk region in general and the Saksagansk-Sursk ore district in particular. A preliminary conclusion was obtained that the ecological-hydrogeochemical conditions of the studied groundwater are primarily determined by: insignificant occurrences of water-bearing rocks (up to their emergence to the surface), close hydraulic connection with surface waters and adjacent aquifers, weak protection against surface pollution due to the lack of regionally sustained confining bed in its roof, the chemical composition of water-bearing rocks, as well as the tectonic conditions of the territory. The authors consider it necessary in further research to take into account the structural and geological features of the crystalline foundation of the studied area in connection with the spread of a wide range of metamorphic rocks and their weathering products, as well as the presence of tectonic faults within the first structural floor.

The factors of the low iodine concentration in soil cover and drinking waters of the second ridge of the Mountain Crimea

Low iodine content in the environment can be one of the main factors of iodine deficiency diseases in humans and farm animals, including hypothyroidism, nodular thyroid tumors, irreversible brain damage in the fetus and newborn. Endemic goiter, caused primarily by iodine deficiency, is an urgent problem for most regions of modern Russia, including the Republic of Crimea. For the Republic of Crimea, along with other regions of the Crimean-Caucasian mountain zone, there is a deficiency of iodine in the lower links of the trophic chain, which provokes iodine deficiency diseases. The aim of the work was to reveal the contrast of iodine distribution in the lower links of the trophic chain: different types of soils for agricultural use and natural waters for drinking purposes from various sources in the Crimean Mountains. The article presents data of the iodine content in the soil cover and drinking water in the Crimean Mountains, on the example of the Bakhchisarai area (in Bodrak river valley). The dependence of the iodine content in the upper horizons of different types of soils, on the content of humus, pH-water soils and cation exchange has been established. It has been confirmed that the content of iodine in natural waters (springs, rivers, lakes) is determined primarily by the composition of water-bearing rocks.

Estimating Thermal Impact on Groundwater Systems from Heat Pump Technologies: A Simplified Method for High Flow Rates

This research delves into the potential thermal effects on underground water systems caused by the use of thermal technologies involving extraction and injection wells. We developed a unique approach that combines straightforward calculations with computer-based modeling to evaluate thermal impacts when water flow rates exceed 2 L/s. Our model, based on a system with two wells and a steady water flow, was used to pinpoint the area around the thermal technology where the temperature varied by more than 1 °C. Our findings suggest that the data-based relationships we derived from our model calculations provide a cautious estimate of the size of the affected area, or ‘thermal cloud’. However, it is important to note that our model’s assumptions might not fully account for the complex variables present in real-world underground water systems. This highlights a need for more research and testing. A key contribution of our study is the development of a new method to assess the thermal impact of operations involving heat pumps. In conclusion, while our proposed method needs more fine-tuning, it shows promise in estimating temperature changes within water-bearing rock layers, or aquifers. This is crucial in the effective use of thermal technologies while also ensuring the protection and sustainable management of our underground water resources.

PREDICTIVE NUMERICAL GEOFILTRATION MODEL OF GROUNDWATER INFLOW INTO THE GOREVSKY GOK QUARRY

Gorevskoe zinc-lead ore deposit is located within a unique terrain: it follows the left bank of the Angara River and lies underneath its current river bed, starting 38 km far from the Angara River mouth. This plays a significant role in the ore field hydrogeology and has a great impact on its further development. The complexity of ore field hydrogeology is defined by a number of natural factors, i.e., the occurrence of both aquifers as well as low-permeable and water-proof layers; tectonic failures (if any) and their functioning in terms of hydrogeology dynamics; variability in terms of water-bearing rocks hydraulic properties; water bodies on the surface and their connection with groundwater flows. All the above mentioned features allow us to classify Gorevskoe deposit hydrogeology as rather complex and complicated. The main task of the work performed was to evaluate and forecast the water inflow to Gorevskii open-pit mine and to determine the groundwater level at the end of mining operations. Because of the deposit rather complex hydrogeology, it was decided to perform the task on the basis of numerical geohydraulic modelling using finite difference method (FDM) in the environment of Visual MODFLOW software tools. The paper describes the following steps of works performed within the project: input data acquisition, processing and analysis; creation of concept-based hydrogeology model; development of hindcasting numerical model; model calibration in the context of environmental conditions and actual mining operations hosted within the open-pit; sensitivity analysis and advanced simulation to develop the forecasting numerical model. When performed, the forecast value in terms of groundwater inflow to the pit has been calculated. Thus, pit groundwater level at the end of mining operations has been developed. Following a number of scenarios applied, model sensitivity analysis has been made and this provided the basis to identify the factors that have the most essential impact on water inflow to the pit.

ANALYSIS OF THE MATHEMATICAL MODEL OF "CHARGING"
 OXYGEN OF WATER-BEARING ROCKS IN THE PROCESS
 OF IN-SITU TREATMENT OF GROUNDWATER

The article describes the method of in-situ groundwater treatment technology, the conditions for modeling the process
 of water injection into the water-bearing rock, the analysis of the obtained mathematical equations.

Hydrogeochemical features of groundwaters of the Ukrainian shield fractured crystalline rocks on the example of Zhytomyr and Vinnytsia regions


 
 
 The chemical composition of groundwaters of fractured Precambrian crystalline rocks corresponding to the Ukrainian Shield aquifer system was investigated. Using the ex- ample of surveyed aquifers of the Vinnytsia and Zhytomyr regions, the similarity of the quantitative and qualitative composition of groundwater confined to the same hydrogeological structure is proven, which is due to similar natural conditions of resource formation (geological structure, the chemical composition of water-bearing rocks, rates of water exchange, amount of atmospheric precipitation, etc.). The dominant role of sulfates in the anionic composition of water samples from the aquifer in the fractured zone of crystalline rocks and their weathering crust (Vysokyi Kamin village, Zhytomyr region) was established. For the Zhytomyr region groundwaters, the dynamics of changes over time in such indica- tors of the general chemical composition as total mineralization, Ca, Mg, SO4, and Cl ions were analyzed for 2017-2019. A significant correlation was found between the concentrations of Mg, SO4, and Cl and their normalized indicators by the amount of water intake, which indicates that the content of mineral substances increases in the studied aquifer with an increase in water withdrawal. This is the evidence of the essential role of the anthropogenic factor in the formation of the general chemical composition of these waters. Using the method of mass spectrometry with inductively coupled plasma (ICP-MS), the features of the trace element composition of groundwaters of the Ukrainian Shield fractured crystalline rocks were established. The obtained concentrations of elements were com- pared with normative values of the World Health Organization and biologically significant concentrations. The lack of several essential elements was revealed. The key potential risks for the health of the population, which constantly uses the investigated groundwaters for economic and potable needs, was outlined. Moreover, the high probability of occurrence of microelementoses with regular use of the investigated groundwaters is emphasized, which are associated with a significant deficiency of such vital elements as Cr (in the Vinnytsia region), Mn, Cu, and, especially, Zn, the content of which is critically low. Subsequently, the findings of this study can serve as a basis for carrying out biogeochemical zoning with the selection of relevant taxa (provinces).
 
 

Experimental study on the failure process of water-bearing rock under uniaxial tension based on dominant frequency analysis of acoustic emission

Experimental study on the failure process of water-bearing rock under uniaxial tension based on dominant frequency analysis of acoustic emission

Studies on the Deformation and Macro-Micro-Damage Characteristics of Water-Bearing Sandstone under Cyclic Loading and Unloading Tests.

The study of the deformation characteristics and damage evolution law of the underground water-bearing rock mass under reciprocating loads such as mine earthquake and mechanical vibration is a very crucial aspect of underground engineering. In this pursuit, the present study was envisaged to assess the deformation characteristics and damage evolution law of sandstone with different water contents under various cycles. Specifically, the uniaxial and cyclic loading and unloading tests, X-ray diffraction (XRD), and scanning electron microscope (SEM) tests of the sandstone under dry, unsaturated, and saturated conditions were carried out under laboratory conditions. Subsequently, the change laws of elastic modulus, cyclic Poisson's ratio, and irreversible strain in the loading section of sandstone under different water content conditions were analyzed. Based on the two-parameter Weibull distribution, the coupled damage evolution equations of sandstone under water content and load were established. The results showed that with an increase in the water content in the sandstone, the loading elastic modulus of the corresponding cycles exhibited a gradual decrease. Microscopic analysis revealed that kaolinite was present in the water-bearing sandstone in a lamellar structure, with flat edges and many superimposed layers, and the proportion of kaolinite gradually increased with an increase in the water content. The poor hydrophilicity and strong expansibility of kaolinite are the key factors in reducing the elastic modulus of sandstone. With the increase of the number of cycles, the cyclic Poisson's ratio of sandstone experienced three stages: an initial decrease, followed by a slow increase, and finally a rapid increase. The decrease was mainly observed in the compaction stage; the slow increase existed in the elastic deformation stage; and the rapid increase was seen in the plastic deformation stage. Furthermore, with the increase of water content, there was a gradual increase in the cyclic Poisson's ratio. The concentration degree of the distribution of the rock microelement strength (the parameter m) under the corresponding cycle of sandstone with different water content states exhibited an initial increase followed by a subsequent decrease. With the increase in the water content, the parameter m under the same cycle gradually increased, and the change rule of parameter m corresponded to the development of internal fractures in the sample. With an increase in the number of cycles, the internal damage of the rock sample gradually accumulated, and the total damage increases gradually but the growth rate decreases gradually.

Hydrogeochemical Characteristics and Human Health Risk Assessment of Fluoride Enrichment in Water in Faulted Basins of Qinghai-Tibet Plateau—A Case Study of Sanhe Plain in Guide Basin

Fluoride (F) is an essential element of drinking water for human health, especially for bone development and enamel creation. However, if the fluoride content in drinking water is higher than 1.5 mg/L or lower than 0.5 mg/L, it will cause endemic diseases, such as dental fluorosis. There are two main hydrogeological characteristics: the properties of the water-bearing rocks and groundwater conditions controlled the groundwater in guide basin. The geothermal water can be divided into fracture convection and sedimentary basin geothermal water according to its geological environment and heat transfer mode. Inductively coupled plasma spectrometry is a significant tool for groundwater quality analysis. The geochemical factors of fluoride enrichment in confined geothermal water mainly include pH, ion exchange, and mineral saturation. Both groundwater samples are slightly alkaline, while the phreatic water and surface water record pH values of 8.5, 7.78, and 7.8, respectively. The salinity of groundwater water is not high, but for confined geothermal water, phreatic water, and surface water measures 706.0, 430.1 and 285.9 mg/L respectively. The higher the pH of groundwater, the more beneficial it is to the enrichment of fluoride. In contrast, the main cations in phreatic water and surface water are calcium ions and magnesium ions. The anions in groundwater and surface water mainly include SO42− and HCO3−, followed by Cl−, indicating that the groundwater and surface water here is mainly leaching. Fluoride was shown to be positively correlated with sodium and bicarbonate. Moreover, the results indicate that F− enrichment is usually associated with high HCO3− and Na+ concentrations in water, while a high Ca2+ concentration tends to lower the F− concentration in water. This means that the ion exchange between calcium ions and sodium ions may lead to fluoride enrichment in natural water. As mentioned above, high-sodium and low-calcium water are favorable for fluoride enrichment. Moreover, saturation indices of fluorite, gypsum, dolomite, and calcite, as well as the saturation index of fluorite, represent a vital method to understand the fluoride enrichment. According to this study, fluoride as a pollutant poses great risks to human health overall, whether lower than or higher than the drinking water limit. Children face higher health risks than adults caused by confined geothermal water drinking intake. This study suggests that groundwater treatment should be conducted to reduce fluoride concentration in drinking water. It is suggested that when confined geothermal water is used as drinking water, it should be mixed with phreatic water and surface water in a certain proportion to make the fluoride in groundwater reach the range of safe drinking water.

ROTATIONAL DYNAMICS AS A FACTOR OF HYDRODYNAMIC REGIME PONTIAN AQUIFER IN THE ODESSA

Traditionally, structural and geological features water-resistant and water-bearing rocks are the main factors shaping the Pontian aquifer Odessa and its hydrodynamic conditions and the main causes of secular changes in the balance of receipts elements are water intake man-made origin. The apparent role of these factors is not denied. However, the dynamics of the hydrodynamic parameters of the intra-Pontian aquifer caused by how the hydraulically effective interblock zones of high permeability in the geological structure of the water-bearing rocks. And this effectiveness is primarily determined by the gravitational factor, which in this case is mediated by the variations of velocity and acceleration of the axial rotation of the earth - rotational dynamics.

Natural radioactivity of groundwater in Vendian deposits in St. Petersburg Region

The study is focused on the hydrogeological conditions and the chemistry of groundwater of the Vendian aquifer in the western part of the Leningrad oblast (Karelian Isthmus and the area near Sosnovy Bor town) and St. Petersburg City, where groundwater features higher radioactivity, but nevertheless it is used for drinking water supply. Data on the radiological characteristics, which have been determined in the estimation of the quality of groundwater used for drinking are generalized and analyzed. These characteristics include the gross alpha and gross beta activity and the specific activity of natural radionuclides 222Rn, 226Ra, 228Ra, 210Pb, 210Po, 238U, and 234U. The data were subjected to statistical and correlation analysis to determine the hygienic criteria for the use of groundwater of this aquifer for drinking water supply and to study the sources and the processes of formation of the natural radiological background. Groundwater quality standards were shown to be exceeded in the majority of the analyzed wells. The brackish water in the southern, deeper, part of the aquifer system was shown to have higher radioactivity and relatively high concentrations of 226Ra, 228Ra, 210Pb, and 210Po, compared with fresh water in the northern part of the territory, of which higher, though nonuniform, 222Rn activity is typical. Relationships between the radiation characteristics of groundwater are considered along with the causes of formation of groundwater radionuclide composition as a result of the higher radioactivity of the host deposits and the chemistry of groundwater; changes in the radiological and hydrochemical background groundwater characteristics from the north to the south are characterized in accordance with the subsidence of the aquifer system and an increase in the stagnation of the hydrochemical regime. The analysis of the well-known relationship between the concentrations of radium isotopes in groundwater, uranium and thorium isotopes in the host rocks, and groundwater residence time in the aquifer, along with the comparison of the available field data with calculation results, suggested the conclusion that the concentration of uranium in the water-bearing rocks in the major portion of the area under consideration is higher than its regional mean values.

Analysis of the main factors determining the value of the specific flow rate of a water well

Purpose of research – numerical characterization of the main factors affecting the value of the specific flow rate of a water well. The relevance of the study is due to the possibility of using the obtained functional relationships to predict the value of the specific flow rate of a water well. Research methods: interpretation of gamma logging curves of water wells, correlation of its results with the core survey data, interpolation of the obtained values over the section area, processing of hydrodynamic well testing materials, comparison of its results with the data of geophysical research, establishment of statistical relationships between the parameters. The results of the study and their application. It was found that the value of the double difference parameter of natural radioactivity of water-bearing rocks statistically significantly correlated with the value of the clay content of core samples, studied in the laboratory way, as well as with the value of water permeability of rocks determined by hydrodynamic tests wells, which allows using this parameter to characterize the filtration properties of rocks aquifer by the value of their clay content. Significant statistical relationship was obtained between the specific flow rate of the water intake well and water conductivity of water-bearing rocks, the parameter of imperfection of the well by the nature of the formation opening, as well as the parameter, numerically equal to the ratio of the well filter length to the value of the double difference parameter of natural radioactivity of rocks of its installation interval. The presence of statistical uncertainty in the relationships is due to the mutual influence of the parameters. The obtained functional relations can be used in the design of wells. Conclusions. During the study the assumption was confirmed that water intake wells with the longest water intake part, equipped in the least clayey and, accordingly, more water-permeable interval of aquifer have the least value of imperfection by nature of formation opening and are able to provide the highest specific flow rate. Such wells are the most effective in operation.

Insights From a Combined Analysis of Acoustic Emission Signals for Water-Bearing Rocks in Four-Point Bending Tests: Failure Mode Classification and Strength Degradation

Insights From a Combined Analysis of Acoustic Emission Signals for Water-Bearing Rocks in Four-Point Bending Tests: Failure Mode Classification and Strength Degradation