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The composition of the organic matter (OM) of coals in the Ulug-Khem Basin has been studied. According to Rock-Eval pyrolysis data, this OM is a type III kerogen, sometimes significantly oxidized. The coal of low-grade metamorphism has a high hydrocarbon potential. Based on the gas-liquid chromatography and chromatography-mass spectrometry data on the distribution of n-alkanes, isoprenoids, polycyclic biomarkers, and aromatic hydrocarbons, we have established the composition of the primary OM of the coals and the grade of OM metamorphism. The primary OM of the coals consists mainly of remains of aquatic vegetation and terrigenous OM. The latter includes conifer remains, which are identified from the presence of 4β(H)-19-norisopimarane in the aliphatic fraction of bitumen and from the domination of retene over cadalene and 6-isopropyl-1-isohexyl-2-methylnaphthalene in the aromatic fraction.

This paper presents an alternative variant of stratigraphic subdivision of the upper Riphean-Vendian deposits (approximately corresponding to the Neoproterozoic Erathem of the International Chronostratigraphic Chart (ICC)) of the Bashkir Mega-Anticlinorium (BMA), based on the modern concepts of changes in the biosphere, atmosphere, and hydrosphere (and, accordingly, in the climate and the course of sedimentary processes) in the period ~1000-540 Ma, with regard to the results of recent studies and the proposals for improving the Russian General Stratigraphic Scale (GSS) of the Precambrian. The strict necessity of subdividing chronostratigraphic and lithostratigraphic units is shown. The presented data give grounds to regard the Zil’merdak Formation as a Group and assign three of its lower formations to the Middle Riphean (Yurmatinian). It is shown that the period of accumulation of the Karatau Group (comprising the Katav, Inzer, Min’yar, and Uk formations) was significantly shorter than the duration of the Late Riphean (Karatavian). Special attention is focused on the age of the Uk Formation (analysis of the existing data made it possible to refine its stratigraphic position): It formed, most likely, in the period 780-740 Ma. A high uncertainty of the stratigraphic position of the overlying geologic bodies is demonstrated. The Bakeevo, Tolparovo, Suirovo, and Kurgashla formations must be regarded as part of the Terminal Riphean (Arshinian). The Arsha Group, comprising the Bainas, Makhmutovo, Igonino, and Shum formations in the Tirlyan trough and represented by the Krivaya Luka Formation in the Krivaya Luka syncline, should not be totally assigned to the Terminal Riphean. It is proposed to exclude the Bakeevo Formation and the Tolparovo-Suirovo sequence from the Asha Group, because these deposits are, most likely, a modification of the Arsha Group located on the western flank of the BMA. The Uryuk Formation is probably of pre-Vendian age. The current contradictory data on the stratigraphy of the supra-Uryuk unit of the Asha Group are interpreted. The ages of the geologic bodies composing the Group and its stratigraphic interval still call for a thorough study.

We studied the middle Cambrian unit of the Kuonamka Formation section on the Kyulenke River (Siberian Platform) and performed its biostratigraphic subdivision based on trilobites. The middle Cambrian section has intervals corresponding to the regional zones of the Amginian Stage. Six levels with mass accumulation of fauna remains have been revealed: Two levels are located within the Ovatoryctocara Zone; the third level is at the boundary between the Ovatoryctocara and Kounamkites zones; the fourth layer is confined to the roof of the Triplagnostus gibbus Zone; and the fifth and sixth levels are located within the Tomagnostus fissus-Paradoxides sacheri Zone. The composition of rocks and bitumens of their organic matter (OM) has been studied, including the geochemical specifics of the mineral components of rocks (iron, sulfur, and СО2) and of saturated hydrocarbons of bitumens as well as noncarbonate carbon isotopes in the OM. It has been established that the OM sedimentation took place under normal aeration of the sea basin waters, without hydrogen sulfide contamination of the bottom waters. The intensity of chemical and biochemical transformations of mineral and organic components during diagenesis was controlled by the contents of organic carbon and sulfate ion, the activity of the anaerobic prokaryote community, and the rate of sediment mineralization. We have also established relationships between the content of organic carbon in potentially oil source rocks and the contents of iron oxide, total sulfur, and sulfide and sulfate sulfur as well as the ratios of saturated hydrocarbons. The alternation of highly carbonaceous black shales and carbonaceous rocks is apparently due to a change in the composition of biologic communities of microorganisms (sources of hydrocarbon biomarkers) and in the intensity of OM transformation during diagenesis. We assume that the OM transformation included sulfate reduction and dealkylation of high-molecular steroids in the unconsolidated OM-enriched marine sediments with the participation of bacteria. The intensity of these processes depended on the mass of the primary OM, the amount of sulfate ion, and, hence, the pH and Eh of the medium.

The paper presents new data on the upper Silurian litho- and biostratigraphy of the Gorny Altai area. Sediments within this interval store a succession of taxonomically representative middle-upper Ludfordian, lower Pridoli, and Lower Devonian (Lochkovian-Pragian) conodont assemblages. The new fauna constraints made a basis for updated correlations of the local and regional stratigraphic units at the Silurian/Devonian boundary of Gorny Altai with the stages of the International Stratigraphic Chart. The correlation results reveal a mismatch between the boundaries of the local and regional Silurian units and the respective boundaries of stages in the International Stratigraphic Chart.

In order to determine the seismotectonic activity of faults in the Holocene, we performed trench studies of the ruptures produced by the catastrophic Mogod earthquake (5 January 1967, М = 7.5-7.8, I ₀ = 9-10) in the junction zone of the N-S striking Hulzhin Gol fault and the NW striking Tullet fault. Paleoseismic interpretation of seismic-deformation sections and radiocarbon dating of the samples allowed determining the kinematics and obtaining, for the first time, the absolute ages of paleoevents preceding the Mogod earthquake. Analysis of the tectonic conditions for realization of earthquake sources has shed light on the complex structure of ruptures in the area of the Mogod earthquake epicenter, within which three segments differing in the displacement amplitudes and kinematics have been identified. The research data indicate the repeated activation of the Tulet and Hulzhin Gol faults in the Late Pleistocene-Holocene. The absolute age of the latest activation is 596-994 AD for the Tulet fault and 11,379-6235 BC for the Hulzhin Gol fault. The cumulative deformation from paleoearthquakes in the trench sections in the Tulet fault zone points to at least two displacements of thrust kinematics, with the latest of them having an amplitude of 2.8 m. The paleoearthquake in the Hulzhin Gol fault zone is characterized by the presence of lateral slip. The amplitudes of deformations attest to earlier earthquakes similar in energy to the 1967 Mogod event or even stronger in the fault node. The obtained data on the timing of these earthquakes and the amplitudes of the accompanying displacements made it possible to estimate slip rates along the faults: 0.2-0.3 m/kyr horizontal-slip rates on the Hulzhin Gol fault and 0.5-0.7 m/kyr vertical-slip rates on the Tulet fault.

The Gobi-Altai, Mongolia, includes high mountain ranges that have accommodated the compressional stresses derived from the collision between the Eurasian and Indian Plates. The Gurvan Bogd, which is one of the main mountain ranges in the Gobi-Altai, is a restraining bend along the Bogd sinistral fault. Although surface ruptures did not form near the Artz Bogd during the M_w = 8.1 Gobi-Altai earthquake of 1957, it is still active, as evidenced by a growing topography (i.e., forebergs). Six foreberg ridges have formed in the foreland of the Artz Bogd, which are considered to be the result of surface deformation of alluvial fans due to thrusting. One stream has cut down to expose a foreberg tip, providing the opportunity to explore the slip evolution of the region. Here we map a growing fault structure related to blind thrusting. We identify five faulting events from an analysis of the outcrop and apply optically stimulated luminescence dating to the faulted sedimentary layers, yielding an average slip rate of 0.045 ± 0.007 m/kyr and an earthquake recurrence interval of 5.8 ± 0.5 kyr over the last ~32 kyr. Furthermore, the long-term (~600 kyr) uplift rate of the foreberg is 0.067 ± 0.007 m/kyr, as deduced by dividing the vertical displacement of the alluvial fan surface by the ¹⁰Be surface exposure ages of boulders on the fan. The discrepancy (20-30 %) between these two deformation rates may be due to the different timescales they cover and an along-strike gradient in slip rate.

Terraces at four hypsometric levels were studied in the Vuoksa River basin (northern part of the Karelian Isthmus, NW Russia). New data on nine sections of late Quaternary-Holocene sediments have been obtained. Their age has been determined (for the first time for surface deposits in the studied region) in the interval from 90 to 2 ka. The terrace sediments are disturbed by deformations (faults, folds, and liquefaction) caused by six strong earthquakes in that period. The relationships among the terrace levels, ages, stratigraphy, and structures of loose sediments point to their formation under the impact of differentiated tectonic motions triggered by the activation of the ancient “Vuoksa” fault zone in the late Neopleistocene and Holocene.

The problem of hydraulic fracture development near a circular cavity is considered in a three-dimensional homogeneous elastic medium. The results of numerical calculations using the extended finite element method (XFEM) implemented in the ABAQUS software package are presented. Different variants of the position of an initial disk fracture relative to the cavity are considered. Some patterns of a 3D hydraulic fracture development near the cavity are found.

According to the borehole logging analysis and near-field transient electromagnetic sounding method, a positive electric resistivity anomaly was detected from top to bottom along the section above the abandoned coal seam. This anomaly indicates a downward movement of groundwater and saturation of rocks with gas.

To study the stress state of “soil body with an inclined earth surface - a system of parallel tunnels” objects, an analytical calculation method is used, which is developed on the basis of obtained new solution to corresponding elasticity theory problem. This method is implemented as a computer program that allows numerical modeling in practical design. Examples of calculation are given.

This article proposes a method based on the disruption theory of an arbitrary discontinuity (the Riemann problem) to determine the shock wave parameters on the wall of an explosion cavity. Two possible variants of detonation wave refraction on the explosion cavity wall are described. The detonative decomposition of emulsion explosives is also considered, and an equation of state for gaseous explosion products is proposed, which enables the estimation of detonation parameters while accounting for the incompressible volume of molecules.

The approaches to the creation of databases that accumulate various information about the deposits of solid minerals are considered. The structure of the database of rocks of the Elginskoe coal deposit and the procedure for filling with information of its constituent sections are proposed. It is shown that the database use provides the highest level of information and analytical support of the geotechnological problems focused on the safe mining and completeness of reserves extraction from the subsoil. A number of coalfield models have been built using specialized software based on the database. The stability analysis of overburden massif of the coalfield has been carried out and geomechanical conditions of open-pit sides have been evaluated.

The problem of constructing a continuous model of hierarchical block geomedium is considered. The basic structural element providing the geomedium structuring is determined, and transition from a hierarchical block to a hierarchical structured medium is discussed. The introduction of four structural levels is sufficient for modeling the geomedium within the Earth’s crust. To describe the fractured structures, a non-Euclidean model of the continuous medium is applied, which considers the violation of deformation compatibility conditions. An algorithm for the transition to a continual description of such structures is presented and nonsingular solutions for a plane-stressed field are constructed. The performed analysis showed that this approach requires hierarchical non-Euclidicity and monolithic block principles.

A method estimating the stress state of anisotropic rock mass around an excavation of an arbitrary cross section is proposed. The technique is based on a new solution of the plane problem of anisotropic elasticity theory obtained using Lekhnitsky complex potentials. For a number of anisotropic rocks, the dependences of maximum compressive and tensile stresses in rock mass around the arched excavation on the inclination angle of an isotropic plane have been found. Comparison of stress distribution around excavations driven in isotropic and anisotropic rock masses is performed.

The authors discuss the structure and formation character of technogenically changed subsoil. A quantitative assessment of the stability of technogenically changed rock mass is proposed, obtained as the sum of the indicators determined using various geophysical and geomechanical methods and characterizing the array of indicators converted into dimensionless quantities by the ratio of their values changed during mining operations to the initial values.

Comparison of Brazilian tensile strength with uniaxial tensile strength is presented. It is noted that on the basis of only statistical processing, it is possible to obtain only rough estimates of direct tensile strength from the measured Brazilian strength. To agree on these values, models that take into account the structure of the material should be used. Taking into account the biaxiality of the stress field, which leads to a decrease in Brazilian strength compared to direct tensile stretch, and considering the nonuniformity of tensile stresses causing the opposite effect, it is possible to correlate the values of tensile strength measured by different methods.

The necessity of expanding the possibilities for controlling the explosive action to obtain a uniform rational fragmentation of the run-of-mine with a minimum yield of oversized and fine low-grade fractions is substantiated. The methodological problems of applying the smoothed particle method for 3D modeling and studying the patterns of dynamic loading of a rock mass, the uniformity and intensity of crushing in different explosive zones, as well as problems of two- and three-dimensional model calibration are considered. The method is calibrated by simulating the fragmentation process by an explosion in comparison with experimental results on blasting rock samples during the explosion of an elongated borehole charge. Work was carried out to study the influence of drilling and blasting parameters and kinetics of energy release on the intensity and uniformity of fragmentation. The regularities of the effect produced by specific consumption of industrial explosives, the rate of energy release; the distance between boreholes, the diameter of borehole charges, as well as air gap values on the intensity and uniformity of crushing in different explosive zones are determined.

The results of numerical modeling of rheological processes both in the potash rock mass in the vicinity of an underground loading complex and in the lining of an underground structure are presented. An algorithm is proposed for solving the problems of calculating the durability of large-scale underground structures with an insufficient amount of initial data on the rheological properties of lining materials for underground structures and the enclosing rock mass. It is shown that even in such conditions, it is possible to qualitatively assess their geomechanical state in the long term. Comparison of various approaches to modeling rheological processes is made.

The problem on elastoplastic deformation and failure of rocks around cylindrical and spherical cavities under the action of internal and external pressure is considered. The pressure during hydraulic fracturing is customary determined by the theory of maximum normal stress. However, the known laboratory experimental studies are not confirmed by this theory. For this reason, it is proposed to determine the limiting pressure using different experimentally justified failure criteria.

The results of calculating the stability of a slope on which the dump is planned to be placed are presented. Safe direction of dumping on the slope is determined, which ensures the slope stability during mining mountaintop deposits of Kyrgyzstan.

The influence of block structure of the rock mass on the stability of sides of mountaintop quarries is estimated. The results of laboratory studies of deformation and destruction along the contacts of blocks, depending on the composition of filler between the blocks, are presented. It is found that shear resistance along the contacts of blocks depends on the composition and internal friction angle of the filler.

The formulation of the problem and results of studying the stress state of the support and rock mass around the excavation in rocks with low values of the fracture strength are presented. The features of performing geomechanical calculations in inhomogeneous continuous medium with significantly different mechanical properties and geometric dimensions are discussed. The nature of support deformation when filling the voids formed during the rock destruction in the roof and sides of the excavation with foaming phenolic resins is determined .

Based on the results of long-term researches in construction and subsequent operation of a railway tunnel using the automated monitoring system, the formation pattern of the stress-strain state of permanent lining made from cast reinforced concrete was obtained. It is found that vibrodynamic loads from transport to the tunnel foundation affect the exclusion of temporary unclosed support from the work with surrounding rock mass .

Studying of rock mass deformation with weak zones is based on the principal property of applied nature that limits incorrectness: the influence of an underground excavation on the stresses and displacements in rock mass attenuates to zero as the distance increases - this is a postulate. The author suggests reducing the problem to solving an additional problem on tensile stresses at the underground excavation boundary to ensure uniqueness and correctness of the elastic solution.

The mechanism of blasting destruction of coal is considered using a combined model of gas-saturated coal, which describes the relationship between explosive damage of a coal seam and subsequent gas release. On the basis of this model, the numerical method of smoothed particles is used to study the development of destruction zones and stress-strain state of a coal seam in the vicinity of a borehole charge after blasting. The obtained patterns help to predict the reaction of coal to explosive dynamic impact. This may be of considerable interest for the development of technology for preliminary degassing of coal seams, as well as for theoretical description of the processes occurring during coal and gas emissions. In this regard, the preparation mechanism of gas-dynamic fracture of a stack of outburst-hazardous (broken) coal under explosive action on a coal seam is considered. The research includes studying the conditions for crack formation in the zone farthest from the blast hole, modeling the filling of induced cracks with methane, which is initially in the coal in a dissolved state, and estimating the onset time of induced crack propagation due to free methane pressure in the crack. It was found that, depending on the mechanical and diffusion parameters of coal, the crack initiation time can vary from tens of seconds to many hours. The research results can be useful in the development of a theory of explosive action on a coal seam, which is used in a set of measures to reduce the hazard of sudden coal and gas emissions.

The physical and mechanical properties of soil from the place of landsliding are studied in laboratory conditions. The problem is solved under the assumption that the landslide mass before and after landsliding remains unchanged. The value of the landslide mass is determined. By constructing various possible sliding surfaces and determining stability factor for each of them, the most dangerous sliding surface was found. To ensure the safety of residential settlements and other objects located at the base of landslide slopes, it is necessary to know the distance that the landslide will travel when fully unloaded. The distance of displacement of landslide masses in the horizontal section is determined.

The density ratio is normalized with respect to the theoretical maximum density ratio of a sphere packing, which is 0.7405. The experimental data show that the density ratio of a packing of sized glass balls changes during cyclical shearing .

An analytical method is presented for determining the stress state of a rock mass in the vicinity of a circular opening, taking into account the influence of contact anchors with high rigidity. The method is based on the solution of a plane problem from the elasticity theory about the equilibrium of a weighty isotropic medium with a circular hole, around which there is a certain region reinforced with an arbitrary number of radially installed rods with high rigidity. The calculation examples illustrating the possibilities of the method are presented. For the purpose of comparison, the corresponding results of computer modeling using the finite element method are considered.

The problems of calculating the stress-strain state of an ore body, enclosing and backfilling masses during the development of mining operations at deep horizons are considered. The previously developed algorithm for taking into account the sequence of stoping and backfilling operations to redistribute the stress fields in rocks for modeling the nonlinear properties of backfilling material has been modernized. The calculation is carried out by the method of conic elements using the stiffness matrix formed for an intact rock mass. The nonlinear behavior of backfilling material is taken into account using the initial stress procedure that is also used to model the sequence of sinking and backfilling of stopes.

The results of mathematical modeling of permafrost rock mass deformation around a mine working with circular cross-section are presented and the influence of thawing on stress state of the rock mass and mine working stability in conditions of a hydrostatic stress field is studied. It is shown that there is a critical size of the thawing halo, upon exceeding which the working starts loosing stability .

The issues concerning the influence of temperature factor on safety and efficiency during the underground mining of mineral deposits in the areas with permafrost rocks are set forth. The features of mining operations and the formation of a thermal regime in alluvial mines of the permafrost zone have been determined. It is shown that the main requirement for regulating the thermal regime of a mine is to prevent thawing of dispersed rocks surrounding mine workings. The results of predictive calculations (by the method of mathematical modeling) of the temperature regime in air supply workings, as well as in enclosing rock mass of a designed alluvial mine, are presented. The results of mathematical modeling of the temperature regime of soils in the area of pile foundation of a tower-type drop hammer and the mouth of a vertical shaft are considered. Based on the results of numerical modeling, recommendations are given to organize automated control of soil temperature (horizontal wells) of the wellhead.

The parameters of physical, mechanical, rheological and water properties of clay rock in the Kara-Keche coal quarry are presented. It is found that in relation to water, gray clay is a swelling-proof and impervious rock. Its presence at the boundary of slip line surface contributes to the activation of landslide phenomena in the open-pit sides. It is determined that gray clay has a pronounced rheological ability to develop plastic flow deformations. The dependence of effective viscosity of gray clay on humidity value was revealed. It is shown that theoretical and experimental values of effective viscosity are in good agreement.

The behavior of cohesion coefficients and internal friction angles depending on the linear or nonlinear representation of the Mohr envelope as a functional dependence of the shear stress on the normal stress is studied. The calculations were based on the reference data concerning ultimate compressive and tensile strength of rocks. The linear dependence was constructed as a tangent drawn to two Mohr circles, and nonlinear dependence - as a relationship recommended by the domestic standard.

The problem of penetrating a weighty rock mass with the Coulomb-Mohr plasticity condition with a rigid nondeformable wedge-shaped tool is being solved. In this case, the relations on the characteristics, as a consequence of differential equilibrium equations, are obtained by the terms that identify them with ordinary linear differential equations of the first order. As a result of equation integration, the required values of contact stresses at the “tool-rock” interface are determined. The ultimate load depends both on the angle of tool sharpening and physical/mechanical rock characteristics, and the depth of penetration.

In the axisymmetric case of Leibenson - Ishlinsky formulation, the problem of stability loss in a mine working with initial circular cylindrical shape is solved. It is assumed that at the moment of stability loss bulges are formed, facing the inside of the mined-out space. The rock mass around the mine working is considered in one of three states: elastic, elastoplastic and post-limiting deformation. The critical load depending on the length of working, radius and physical/mechanical rock properties is determined.

It is shown that inhomogeneity of the structure and variability of the rock mass properties has a great influence on the mining efficiency of complex deposits, which include the section Uregolsky of the open pit mine Kiyzassky. Field observations were carried out to assess the state of the rock mass on the overburden benches of the working side of the mine, which showed constant differences in their structure and texture along the mining front. The expected differences and variability of the physical and mechanical properties of rocks were confirmed by the laboratory study of rock samples taken from the open-pit face. It is found that natural geological inhomogeneity of the overburden properties significantly affects the sequence and processes of drilling, blasting, excavation, transportation and dumping operations. Fracturing of the rock mass enhances the influence on these processes, general and local geomechanical stability of mine workings.

The trends of improving the technology of stope mining are determined, taking into account the design parameters of geotechnology and the figure of ore drawing. Efficient options of sublevel caving with rock preparation and rock pillar above the drill haulage horizon, as well as ore pretreatment are considered.

The use of the southern cage shaft of no. 11 mine within the structure of water-drainage system of M. Gorky Mine for water pumping using submersible pumps in order to ensure the safe operation of ground surface objects is substantiated.

The results of studying technogenic seismicity that arose in the area of open pit coal mining in the Novosibirsk region are presented. The mining intensity at the Gorlovskoye coal deposit increased significantly in the last decade and seismic activation of the subsoil of the Gorlovskaya depression is formed in response to the technogenic effect. Earthquakes with a magnitude of 4.5 experienced in Novosibirsk and its suburbs have been recorded in coal deposit area since 2019

A brief assessment of the mining, geological and geomechanical conditions for the development of production horizons of the Central Stocks section of the Kazskoye field is given. The analysis of rock pressure manifestation in a dynamic form is carried out. The stress-strain state of the rock mass has been diagnosed. The measurement results of strain increment level using depth and contour benchmarks are presented and the category of rockburst hazard is determined for different horizons. The stress-strain state of the rock mass was measured with the SB-32M device according to the parameters of acoustic emission. The time criteria for assessing the rockburst hazard were adjusted on the basis of comparing the results of recording the parameters of acoustic emission and the level of stresses obtained from the strain increment results at the stations of deep and contour benchmarks. A project has been developed for the installation of mobile seismic monitoring for recording events in stoping influence zone.