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Date submitted2023-02-27
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Date accepted2023-10-25
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Date published2024-04-25
Microstructural features of chromitites and ultramafic rocks of the Almaz-Zhemchuzhina deposit (Kempirsai massif, Kazakhstan) according to electron backscatter diffraction (EBSD) studies
Microstructural features of the main rock-forming minerals of host ultramafic rocks (olivine, orthopyroxene) and chrome spinel from ores of the Almaz-Zhemchuzhina deposit were studied using the electron backscatter diffraction method. For ultramafic rocks, statistical diagrams of the crystallographic orientation of olivine and orthopyroxene were obtained, indicating the formation of a mineral association in conditions of high-temperature subsolidus plastic flow in the upper mantle. The main mechanisms were translation gliding and syntectonic recrystallization. Olivine deformation occurred predominantly along the (010)[100] and (001)[100] systems. The textural and structural features of chromitites reflect plastic flow processes, most pronounced in lenticular-banded ores. Microstructure maps in inverse pole figure encoding show differences in the grain size composition of the ores: areas consisting of disseminated chromitites are characterized by a finer-grained structure compared to lens-shaped segregations of a massive structure. Analysis of microstructure maps shows that during the transition from disseminated to massive ores, there is a widespread development of recrystallization, adaptation of neighbouring grains to each other, resulting in homogenization of crystallographic orientation in aggregates. The data obtained develop ideas about the rheomorphic nature of chromitite segregations in ophiolite dunites. It is assumed that the coarsening of the structure of massive chromitites is critically associated with an increase in the concentration of ore grains during solid-phase segregation within a plastic flow, when individual chrome spinel grains, initially separated by silicate material, begin to come into direct contact with each other.
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Date submitted2022-10-26
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Date accepted2023-02-13
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Date published2023-07-19
Determination of the grid impedance in power consumption modes with harmonics
The paper investigates the harmonic impedance determination of the power supply system of a mining enterprise. This parameter is important when calculating modes with voltage distortions, since the determined parameters of harmonic currents and voltages significantly depend on its value, which allow the most accurate modeling of processes in the presence of distortions in voltage and current. The power supply system of subsurface mining is considered, which is characterized by a significant branching of the electrical network and the presence of powerful nonlinear loads leading to a decrease in the power quality at a production site. The modernization of the mining process, the integration of automated electrical drive systems, renewable energy sources, energy-saving technologies lead to an increase in the energy efficiency of production, but also to a decrease in the power quality, in particular, to an increase in the level of voltage harmonics. The problem of determining the grid harmonic impedance is solved in order to improve the quality of design and operation of power supply systems for mining enterprises, taking into account the peculiarities of their workload in the extraction of solid minerals by underground method. The paper considers the possibility of determining the grid impedance based on the measurement of non-characteristic harmonics generated by a special nonlinear load. A thyristor power controller based on phase regulation of the output voltage is considered as such a load. Simulation computer modeling and experimental studies on a laboratory test bench are used to confirm the proposed method. The recommendations for selecting load parameters and measuring device connection nodes have been developed.
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Date submitted2021-09-29
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Date accepted2022-05-11
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Date published2022-07-13
Tensor compaction of porous rocks: theory and experimental verification
Compaction in sedimentary basins has been traditionally regarded as a one-dimensional process that ignores inelastic deformation in directions orthogonal to the active load. This study presents new experiments with sandstone demonstrating the role of three-dimensional inelastic compaction in cyclic true triaxial compression. The experiments were carried out on the basis of a triaxial independent loading test system in the Laboratory of Geomechanics of the Ishlinsky Institute for Problems in Mechanics of the Russian Academy of Science. The elastic moduli of the material were estimated from the stress-strain curves and the elastic deformations of the sample in each of the three directions were determined. Subtracting the elastic component from the total deformation allowed to show that inelastic compaction of the sandstone is observed in the direction of active loading, whereas in the orthogonal directions there is a expansion of the material. To describe the three-dimensional nature of the compaction, a generalization of Athy law to the tensor case is proposed, taking into account the role of the stress deviator. The compaction tensor and the kinetic equation to describe the evolution of inelastic deformation, starting from the moment of the load application are introduced. On the basis of experiments on cyclic multiaxial compression of sandstone, the identification and verification of the constructed model of tensor compaction were carried out. The possibility of not only qualitative, but also quantitative description of changes in inelastic deformation under complex cyclic triaxial compression is shown.
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Date submitted2021-03-18
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Date accepted2021-11-30
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Date published2021-12-27
Deformations assessment during subway escalator tunnels construction by the method of artificial freezing of soil for the stage of ice wall formation
- Authors:
- Evgenii M. Volokhov
- Diana Z. Mukminova
The work is devoted to the study of the processes of displacement and deformation of the surface during the escalator tunnels construction of the subway by the method of artificial freezing of soils. The features of the construction and freezing technology, the rocks characteristics in which the escalator tunnels made are considered. The data of specially organized, full-scale surveying observations of deformations on the earth surface are presented. The main factors influencing deformation processes in the frozen strata of a layered inhomogeneous rock mass with inclined tunneling are determined, the complexity of the predictive task and the need to simplify the design scheme are shown. The work is focused on the assessment of the least studied geomechanical processes of soil heaving-uplifts and deformations during the periods of active and passive freezing stages. When studying the displacements processes of the earth surface and rock mass, the finite element method and analysis of the obtained data using field observations of displacements were used. A simplified calculation scheme is proposed for modeling, which allows taking into account the uneven influence of frozen rocks of an inhomogeneous layered rock mass with a large inclined tunneling. The satisfactory convergence of the data of field surveying observations on the earth surface and the results of modeling geomechanical processes for the period of active and passive freezing stages is shown. The proposed calculation scheme is recommended for the prediction of deformation at the stages of underground construction, characterized by the development of the most dangerous tensile deformations of buildings and structures on the surface.
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Date submitted2020-07-30
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Date accepted2021-03-02
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Date published2021-04-26
Experimental study of thermomechanical effects in water-saturated limestones during their deformation
Stability control of elements of stone constructions of various structures is a prerequisite for their safe operation. The use of modern methods of non-destructive diagnostics of the stress-strain state of such constructions is an effective, and in many cases the only way to control it. Studies of thermal radiation accompanying the processes of solid bodies deformation allowed to justify and develop a method that allows to obtain non-contact information about changes in the stress-strain state in various types of geomaterials, including limestones. However, studies of the water saturation influence of rocks on the thermal radiation parameters recorded in this way are currently superficial. Taking into account the water saturation degree of rocks is necessary when monitoring the mechanical condition of stone structures that are in direct contact with water. The main purpose of this work is to study the dependences of changes in the intensity of thermal radiation from the surface of limestone samples with different humidity under conditions of uniaxial compression. The obtained results showed the expected significant decrease in the mechanical properties (uniaxial compressive strength and elastic modulus) of water-saturated samples in comparison with dry ones. At the same time, a significant increase in the intensity of thermal radiation of limestone samples subjected to compression with an increase in their water saturation was recorded, which makes it necessary to take into account the revealed regularity when identifying changes in the stress state of stone structures established according to non-contact IR diagnostics in real conditions.
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Date submitted2021-01-20
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Date accepted2021-03-15
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Date published2021-04-26
Improving the quality of electricity in the power supply systems of the mineral resource complex with hybrid filter-compensating devices
- Authors:
- Yurii A. Sychev
- Roman Yu. Zimin
The urgency and necessity of choosing and justifying the structures of hybrid filter-compensating devices based on series and parallel active filters to improve the quality of electricity in the power supply systems of enterprises of the mineral resource complex is shown. Mathematical models of hybrid filter compensating devices based on parallel and series active filters have been developed. Based on these mathematical models, computer simulation models of the indicated hybrid structures have been developed. The results of simulation showed the effectiveness of the correction of power quality indicators in terms of reducing the level of higher harmonics of current and voltage, as well as voltage deviations. The degree of influence of filter-compensating devices on the power quality indicators, which determine the continuity and stability of the technological process at the enterprises of the mineral resource complex, have been revealed. It has been established that a hybrid filter-compensating device based on a parallel active filter can reduce the level of higher harmonics of current and voltage by more than 90 and 70 %, respectively, and based on a series active filter, it can reduce the level of higher harmonics of voltage by more than 80 %. Based on the simulation results, the possibility of compensating for the reactive power of a hybrid structure based on parallel active and passive filters has been revealed. The possibility of integrating hybrid filter-compensating devices into more complex multifunctional electrical systems for the automated improvement of the quality of electricity is substantiated, as well as the expediency and prospects of their use in combined power supply systems based on the parallel operation of centralized and autonomous sources of distributed generation.
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Date submitted2019-07-17
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Date accepted2019-10-09
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Date published2020-04-24
Assessment of internal pressure effect, causing additional bending of the pipeline
Article justifies accounting for internal pressure effect in the pipeline, causing additional bending of the pipeline. According to some scientists, there is an erroneously used concept of the equivalent longitudinal axial force (ELAF) S x , which depends on working pressure, temperature stresses, and joint deformations of pipelines with various types of soils. However, authors of the article use ELAF S x concept at construction of mathematical model of stress-strain state (SSS) for complex section of the trunk pipeline, and also reveal it when analyzing the results of calculating the durability and stability of the pipeline. Analysis of SSS for calculated section of the pipeline was carried out for two statements of the problem for different values of operation parameters. In the first statement, effect of internal pressure causing bending of the pipeline is taken into account, and in the second it is neglected. It is shown that due to effect of ELAF S x at p 0 = 9.0 MPa, Dt = 29 °C extreme value of bend increases by 54 %, extreme values of bending stresses from span bending moment increase by 74 %, and extreme value of bending stresses from support bending moment double with regard to corresponding SSS characteristics of the pipeline. In case of neglecting the internal pressure effect causing additional bending of the pipeline (second statement of the problem), error in calculating the extreme value of bend is 35 %, extreme value of bending stresses from span bending moments is 44 %, and extreme value of bending stresses from support bending moments is 95 %.
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Date submitted2019-03-13
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Date accepted2019-09-19
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Date published2020-02-25
Specifying the technical state limit value of the pump pulp without disassembling
The northern part of the territory of the Republic of Sakha (Yakutia) is rich in vast deposits of diamonds. These deposits are developed by the mining company “Almazy Anabara”, which is engaged in the extraction of diamonds at seasonal processing plants using various technological equipment. One of the key types of equipment is the pulp pump of a foreign company “KETO”. The work of pulp pumps of this company in the enrichment of diamond-containing raw materials is accompanied by intensive hydroabrasive wear of their impellers, the service life of which usually does not exceed three months. In practice, untimely replacement of a worn impeller can lead to emergency breakdowns of sealing elements and bearings, which is explained by super-permissible deflections of the shaft of pumping equipment arising from a significant unbalance of the rotor. The main cause of breakdown of slurry pumps at “Almazy Anabara” seasonal processing plants is the inability to quickly identify their ultimate technical condition, the key sign of which is the maximum wear of the impeller. The seasonal beneficiation plants of “Almazy Anabara” currently need a simple and at the same time reliable diagnostic sign of pulp pumps reaching their ultimate technical state, the identification of which can be quickly performed without disassembling and using complex equipment, which is very important when operating pumping equipment in short wash season on the Far North.
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Date submitted2016-09-06
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Date accepted2016-11-15
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Date published2017-02-22
Modelling of fiberglass pipe destruction process
The article deals with important current issue of oil and gas industry of using tubes made of high-strength composite corrosion resistant materials. In order to improve operational safety of industrial pipes it is feasible to use composite fiberglass tubes. More than half of the accidents at oil and gas sites happen at oil gathering systems due to high corrosiveness of pumped fluid. To reduce number of accidents and improve environmental protection we need to solve the issue of industrial pipes durability. This problem could be solved by using composite materials from fiberglass, which have required physical and mechanical properties for oil pipes. The durability and strength can be monitored by a fiberglass winding method, number of layers in composite material and high corrosion-resistance properties of fiberglass. Usage of high-strength composite materials in oil production is economically feasible; fiberglass pipes production is cheaper than steel pipes. Fiberglass has small volume weight, which simplifies pipe transportation and installation. In order to identify the efficiency of using high-strength composite materials at oil production sites we conducted a research of their physical-mechanical properties and modelled fiber pipe destruction process.
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Date submitted2015-12-27
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Date accepted2016-02-26
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Date published2016-12-23
Simulation of rock deformation behavior
- Authors:
- Ya. I. Rudaev
- D. A. Kitaeva
- M. A. Mamadalieva
A task of simulating the deformation behavior of geomaterials under compression with account of over-extreme branch has been addressed. The physical nature of rock properties variability as initially inhomogeneous material is explained by superposition of deformation and structural transformations of evolutionary type within open nonequilibrium systems. Due to this the description of deformation and failure of rock is related to hierarchy of instabilities within the system being far from thermodynamic equilibrium. It is generally recognized, that the energy function of the current stress-strain state is a superposition of potential component and disturbance, which includes the imperfection parameter accounting for defects not only existing in the initial state, but also appearing under load. The equation of state has been obtained by minimizing the energy function by the order parameter. The imperfection parameter is expressed through the strength deterioration, which is viewed as the internal parameter of state. The evolution of strength deterioration has been studied with the help of Fokker – Planck equation, which steady form corresponds to rock statical stressing. Here the diffusion coefficient is assumed to be constant, while the function reflecting internal sliding and loosening of the geomaterials is assumed as an antigradient of elementary integration catastrophe. Thus the equation of state is supplemented with a correlation establishing relationship between parameters of imperfection and strength deterioration. While deformation process is identified with the change of dissipative media, coupled with irreversible structural fluctuations. Theoretical studies are proven with experimental data obtained by subjecting certain rock specimens to compression.
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Date submitted2014-10-08
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Date accepted2014-12-11
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Date published2015-08-25
Modeling of geomechanical processes in ore mass using physically nonlinear model
- Authors:
- A. G. Protosenya
The aim of the article is to develop a method of forecasting the state of stress of the ore mass around excavations for ores of weak and medium strength. The paper presents experimental studies on the deformation of ore samples of low and medium strength in the forging equipment in conditions of volume stress state. A physically nonlinear model is used to describe the deformation process of ore mass. The study of the stress state of physically nonlinear ore mass around excavations of round and valuated cross-sections is performed. Values of coefficients of tangential stress concentrations on excavation contour are found for different types of ore. Solutions to physically nonlinear problems in preparatory excavations in the development of the Yakovlevskiy deposit of rich iron ore using a slicing method are considered. Methods for forecasting the stress state in rock mass around mine excavations can be used to assess their stability in the mining of ore of low and medium strength at the Yakovlevskiy iron ore deposit and in the rock and soil masses.
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Date submitted2009-09-10
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Date accepted2009-11-18
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Date published2010-06-25
Numerical modelling of shear strain near to the crack
- Authors:
- S. E. Mansurova
The behaviour of a material near to a crack is considered at nonlinear shear strain. The plane problem of the nonlinear theory of elasticity in the variation form is solved. Some variants of boundary conditions are used. The numerical results received by a finite element method are presented.
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Date submitted2009-08-25
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Date accepted2009-10-24
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Date published2010-02-01
Geomechanical substantiation of parameters of the fastening of railway tunnels in the conditions of the North Caucasus
- Authors:
- N. A. Belyakov
The article presents the rationale of temporary supports used in the drilling of new mines, which provides for the construction of model projects of reconstruction of old tunnels. Finite-element method analyzed the changes of stress-strain state containing tunnel complex array during the drilling of new mines. Based on the analysis, a number of findings to explore the possibility of reducing the thickness of the permanent support of new mines in tunnel complex - the new tunnel, and transport and drainage culvert.
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Date submitted2009-08-17
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Date accepted2009-10-18
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Date published2010-02-01
Geotechnical engineering and hydrogeological specifics of estimate high-rise buildings construction and operation conditions (in terms of local zone on the right bank of Neva river)
- Authors:
- A. M. Zhukova
In the paper specificity of geotechnical engineering conditions in the local zone of the right river Neva bank are considered. The influence of underground topographies of Pre-Quaternary soils roof formed by paleovalleys on the specificity of engineering geological profile is analyzed. Influence of tectonic faults on physical and mechanical properties of Upper Kotlin clays (Upper Vendian) which it is planned to use as the basis for high-rise constructions is considered. Negative influence of Low Kotlin (Upper Vendian) pressure water-bearing horizon on clay properties in the construction foundation and structural materials is investigated.
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Date submitted2009-07-09
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Date accepted2009-09-03
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Date published2010-04-22
The stress-strain state of the massive of the loose ores in the Yakovlevsky deposit around the minings which were drilled with the combines or with drilling-blast technology
The article presents the consistent patterns of the changes in stress-strain state of the massive by the minings of the first stage of protective overlapping in the Yakovlevsky deposit. The change of the stress-strain condition of the rock massive, which is weaked by the mining was determined by the method of finite elements. The stresses distribution in the massive, the displacement of the contour of the minings, the size of conditional zones of non-linear deformations has been obtained. For stoping passes at the first stage the cutting with combine and application of fastening with the anchors has been suggested.
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Date submitted2009-07-21
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Date accepted2009-09-28
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Date published2010-04-22
The determination of the volume stress-strain conditions of the rock massive with the circular outline mining ensrined with the anchors
- Authors:
- A. G. Protosenya
- N. A. Belyakov
In the article the analysis of consolidating effect from application of the anchor fastening, which using at driving of transport tunnels in the conditions of North Caucasus is produced. The change of the stress-strain condition of the rock massive, which is weaked by the mining of the circular outline is certain with the finite-elements method. On the basis of the executed design the row of graphic dependences, which describes changing of the sizes of limitary areas depending on strength and deformational properties of the rocks. Due to results of the conducted work the direction of further researches is seted.
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Date submitted2008-10-29
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Date accepted2008-12-11
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Date published2009-12-11
Experience in providing the stability of tunnel face and roof during its drivage in proterozoic clays
- Authors:
- V. A. Maslak
Methodology for assessment of state of advance support of face with fiberglass anchors and the working¢s roof – with tube anchors, is given. The results of in-situ experimental observations for efforts in anchors, displacements of excavation and growth of load on the advance supports in its roof are shown.
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Date submitted2008-10-22
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Date accepted2008-12-15
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Date published2009-12-11
Regularities of changes in strength of rocks under complicated stress state, different levels of humidity and pore pressure
- Authors:
- A. T. Karmansky
The conducted investigations allowed to establish the regularities of changes in mechanical properties of rocks with due account of influence of the stress state type, forms and kinds of moisture in rocks. Condition of the final state may be regarded as the criterion of rock failure depending on the moisture content, value of pore pressure and stress state type under constant velocity of deformation.