scholarly journals STUDY OF THE INFLUENCE OF PARAMETERS TECHNOLOGICAL SCHEMES OF EXCAVATION ON THE SUSTAINABILITY OF MINE ROADWAYS WHEN IMPLEMENTING THE CONCEPT OF «SMALL MINES»

2020 ◽  
pp. 64-73
Author(s):  
Svitlana Sakhno ◽  
◽  
Victoria Borodich ◽  
Yevhen Karlov
Keyword(s):  
Coal Mining ◽  
Strain State ◽  
Point Of View ◽  
Practical Significance ◽  
Stress Strain ◽  
Stress Strain State ◽  
Rock Stability ◽  
Complex Mechanization ◽  
Mine Roadways ◽  
First Time

Purpose. Investigation of the influence of the parameters of technological schemes of coal mining on the stress-strain state of the rocks containing the mine roadways in the implementation of the concept of «small mines». Methods. The study used the finite element method and the analysis method. Modeling was carried out by the method of dangerous sections. According to the first variant of the technological scheme, two dangerous sections were selected, according to the second – four. The solution of the problem was carried out in a volumetric setting with observance of the boundary conditions. Results. The analysis of the stress-strain state of the rocks around mine roadways, according to the compared options, made it possible to determine the expected state of the rocks and establish the parameters of the zones of possible destruction. From the point of view of rock stability at the stage of elastoplastic deformation of rocks, the compared options are almost equivalent. Taking into account the shorter time of maintenance of roadways, it is more expedient to use short longwalls. In this version, trapezoidal support is used as the main fastening in the roadways, and in the “traditional” version – metal arch support. It is shown that with significantly lower costs for maintaining mine roadways, their stability when using short-longwall technological schemes is better. The studies carried out make it possible to assert that for “small mines” with small production, technological schemes with short longwalls are more appropriate than the “traditional” technological schemes developed for complex mechanization. Scientific novelty. The study of the stress-strain state of rocks around mine roadways of various shapes and sizes during the analysis of technological schemes for coal mining with short longwalls made it possible to establish the orientation and parameters of the massif sections that pass into an out-of-bounds state. This was done for the first time for the conditions of the Ukrainian Donbass. Practical significance. The availability of information about the expected stress-strain state of the rock mass allows timely planning of methods of fastening and measures to increase the local stability of rocks. Keywords: stresses, deformations, development, coal mine, technological schemes of excavation.

Modeling of the stress-state longwall face during coal mining with the technology of roof management complete drop and stowing

2020 ◽  
pp. 99-106
Author(s):  
I. E. Mazina ◽  
A. A. Stel’makhov ◽  
L. F. Mullagalieva
Keyword(s):  
Coal Mining ◽  
Strain State ◽  
Underground Mining ◽  
Negative Impact ◽  
Hydrological Regime ◽  
Coal Bed ◽  
Stress Strain ◽  
Environmental Friendliness ◽  
Modeling And Analysis ◽  
Stress Strain State

Underground mining of coal deposits has a negative impact on all components of the environment. When developing a coal deposit, it is coal mining technology that determines the scale and consequences of the negative impact. Changes in the stress-strain state of the geo-environment can lead to a violation of the hydrological regime, increased gas emission from the host rocks, the initiation of gas-dynamic processes. Choice of roofing management technology - as a geotechnological method of natural and technical system management determines the environmental friendliness of coal mining and creates safety conditions. The article deals with the technology of roofing control during coal production. For this purpose mathematical modeling and analysis of stress-strain state of the bottomhole part of the coal bed for the conditions of S.M. Kirov is performed. As a result of modeling, two technologies of roof control were analyzed - complete caving and stowing. For the worked out clearing leaves filled with either caving rocks or stowing material, there are characteristic unloading zones in the massif to be worked and overworked, as well as pressure reference zones, which fall on the parts of the pillars associated with the lava. It was found out that the application of the stowing technology creates conditions for minimization of gravitational stresses in the geoenvironment, as well as significantly reduces the potential energy of form change.

scholarly journals Rheology effect determination of the heterogeneous rock massif on the stress-strain state of the breakage face geomechanical system

2018 ◽  
Vol 60 ◽  
pp. 00015
Author(s):  
Vadym Fomychov ◽  
Viktor Pochepov ◽  
Liudmyla Fomychova ◽  
Viktor Lapko
Keyword(s):  
Strain State ◽  
Complex Structure ◽  
Face Advance ◽  
Computational Domain ◽  
Stress Strain ◽  
Stress Strain State ◽  
Heterogeneous Rock ◽  
Mine Workings ◽  
First Time

The purpose of this study is to determine the nature of influence of the rheological properties of the rocks on the results of computational experiments simulating the mine workings contour condition during the breakage face advance. To determine the deformations along the mine workings contour, the calculations have been made of the junction area between the preparatory and stope face mine workings by the finite element method for various parameters of the material models. These data provided the basis for analysis of the patterns development of the rheology modelling influence on the stress-strain state of the geomechanical system. The obtained patterns are described by a function of many variables, and this function determines the limit and degree of rheology effect on the results of calculations. For the first time this pattern takes into account the heterogeneity of the rheological characteristics of rocks and the specifics of the computational domain geometry. The use of the obtained patterns makes it possible to simplify significantly the process of modelling in time and space of the geomechanical systems, which have a complex structure describing the interaction of several objects.

scholarly journals Effect of increasing mining rate on longwall coal mining – Western donbass case study

2016 ◽  
Vol 38 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Olena Sdvyzhkova ◽  
Renata Patyńska
Keyword(s):  
Coal Mining ◽  
Strain State ◽  
Rapid Change ◽  
Rock Stress ◽  
Strength Theory ◽  
Mining Operations ◽  
Stress Strain ◽  
Statistical Strength ◽  
Roof Collapse ◽  
Stress Strain State

Abstract This paper presents the problems associated with the rapid change of the rock stress-strain state in terms of increasing the rate of coal mining. Parameters of the roof collapse are determined depending on the rate of a longwall advancing under conditions of poor rocks. Statistical data are processed to obtain a general trend concerning the mining rate impact on the roof collapse. The statistical strength theory is applied to explain the increase in mined-out space and the size of hanging roof behind a coal face. Numerical simulation is carried out to determine a critical size of mined-out space that provokes a roof collapse. The area of yielded rocks is outlined using the criterion developed taking into account the rate of longwall advancing. A general regularity is obtained to determine the roof collapse parameters. The developed technics gives a possibility to predict the moment of general roof collapse at the initial stage of longwalling to prevent the negative effect of the rapid stress redistribution provoking joints propagation and intensive gas release. The estimation of the rock stress-strain state considering the rate of mining operations can be useful for tasks related to a new technology implementation. The statistical strength theory and failure criterion applied together provides adequate planning of mining activities and the assessment of natural hazards.

scholarly journals Influence of breakages of cable groups on strength ofrubber-cable tractive-transporting element

2021 ◽  
Vol 64 ◽  
pp. 166-174
Author(s):  
I Belmas ◽  
D Kolosov ◽  
O Dolgov ◽  
H Tantsura ◽  
S Onyshchenko
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Strain State ◽  
Elastic Shell ◽  
Practical Significance ◽  
Analytical Determination ◽  
Shear Stresses ◽  
Stress Strain ◽  
Stress Strain State

Purpose. Development and justification of a method of analytical determination of a stress-strain state of a flat rubber-cable tractive-transporting element with breakages of continuity of cable groups in different cross-sections. Methodology of research is in development of a mathematical model of interaction of tractive-transporting element parts considering breakages of groups of random cables, construction of analytical solutions for determining dependencies of force distribution between cables and shear stresses in an elastic shell of a tractive-transporting element with random locations of breakages of cable groups in different cross-sections. Findings. A model of a flat rubber-cable tractive-transporting element with random locations of breakages of cable groups in different cross-sections is developed. Expressions that allow determining a stress-strain state of a flat rubber-cable tractive-transporting element of a hoisting and transporting machine with random locations of breakages of cable groups in different cross-sections are obtained analytically in a closed form. Strength conditions are formulated. Scientific novelty is in establishment of dependencies of interaction of disturbance fields of a stress-strain state of a rubber-cable tractive-transporting element with breakages of continuity of random cable groups in different cross-sections. It is established that disturbance fields caused by breakages of adjacent cables overlap when the breakages are located in one cross-section and there are less than three whole cables located between the broken cables. Disturbance fields also overlap when the same cable or the adjacent cable is broken in both cross-sections and the distance between cross-sections of breakage does not exceed the value, which depends on the design of a flat rubber-cable tractive-transporting element and mechanical properties of its components. Practical significance. The obtained algorithms and strength conditions allow determining a stress-strain state and preventing the breakage of the entire flat rubber-cable tractive-transporting element with breakages of cable groups in different cross-sections. These cross-sections can be: cross-section of the edge of a butt joint, where cables have breakages of continuity; cross-section, which includes the edge of an area of partial restoration of a tractive ability of the element, lost due to breakage of a cable; cross-section of cable or cable group breakage during operation. A possibility of establishing a stress-strain state and the strength conditions of a tractive-transporting element under such conditions allows reasonable determination of a possibility of its further operation in a hoisting and transporting machine.

Numerical Realization of the Method of Subsequent Parameters Perturbation for Calculating a Stress-Strain State of the Shell

2015 ◽  
Vol 799-800 ◽  
pp. 656-659
Author(s):  
Leonid V. Bessonov
Keyword(s):  
Strain State ◽  
Linear Equations ◽  
Numerical Realization ◽  
Point Of View ◽  
Stress Strain ◽  
Stress Strain State ◽  
Arbitrary Configuration ◽  
Systems Of Linear Equations ◽  
Basis System ◽  
Parameters Perturbation

During the application of approximated methods of estimations for calculating a stress-strain state of the shell an explicit question of accuracy and resource-intensiveness of the method is raised. From that point of view, the method of subsequent parameters perturbation (MSPP), developed by Vladlen V. Petrov in 1975, can be called the most effective one. The result of the application of this method is that the solution of a nonlinear model can be reduced to the sequence of solutions of systems of linear equations. The application of the method of Bubnov-Galerkin for solving linear equations is conjugated with the necessity of building the basis system of functions for every concerned problem. The method of building the basis system of functions for the shell with the boundaries of arbitrary configuration is offered in this paper..

ANALYSIS OF THE RESULTS OF NON-DESTRUCTIVE TESTING OF THE STRESS-STRAIN STATE OF THE GLASS SURFACE IN THE GLUING, USING CURRENT-CONDUCTING COATING

2019 ◽  
pp. 20-25
Author(s):  
D. S. Dorofeev
Keyword(s):  
Surface Tension ◽  
Strain State ◽  
Point Of View ◽  
Glass Film ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Stress Strain ◽  
Stress Strain State ◽  
Conducting Coating ◽  
Non Destructive

The article discusses the possibility of monitoring with using SCALP type devices (non-destructive method – NDT) the stress-strain state of external glass from the bonding side when in contact with a conductive coating in products of structural optics (IR). Using the example of two medium-sized IR products, measurements of the surface tension of the glass are given when the antiicing system is inoperative and during operation of this system. The results obtained are considered from the point of view of the accumulation of thermal energy in a closed system (glass-film-glass). Additionally, the obtained results on the possibility of determining the composition of the IR to a depth of 20 mm.

scholarly journals MATHEMATICAL MODELS SIMULATING THE FORMATION OF THE STRESS-STRAIN STATE OF EPIPLATFORM OROGENS

2019 ◽  
Vol 10 (1) ◽  
pp. 21-41
Author(s):  
D. S. Myagkov ◽  
Yu. L. Rebetsky
Keyword(s):  
Mathematical Models ◽  
Strain State ◽  
Point Of View ◽  
Indian Plate ◽  
Small Scale ◽  
Eurasian Plate ◽  
Stress Strain ◽  
Stress Strain State ◽  
Seismological Data ◽  
Geodynamic Processes

The sources of the natural stress-strain state (SSS) of epiplatform orogens are investigated by tectonophysical methods based on seismological data. According to the available data, the horizontal axes of the main deviatoric extension are dominant in depressions, while in the ridges of the orogens, the axes of the main deviatorial compression are dominant.Our comparative analysis is focused on SSS of the orogenic crust. It is generally accepted that the sources of such SSS are geodynamic processes, including the pressure on the Eurasian Plate from the Indian Plate, and the small-scale thermogravitational asthenospheric convection. In the mathematical (analytical) simulation technique used in our study, the main criterion for the correctness of models in terms of tectonophysics is the correspondence between the orientation pattern of the principal stress tensor axes in the crust model to the natural data. According to Model I, the lithospheric SSS under lateral compression is less consistent with the sought-for SSS. Model II also gives the results that do not fully correspond to the stress data from tectonophysical reconstructions. However, additional analysis suggests that asthenospheric convection is a more promising (from the point of view of tectonophysics) geodynamic process for explaining epiplatform orogenesis. In our opinion, more complex and probably non-analytical mathematical models should consider this source of loading of the lithosphere as one of the most significant factors in the formation of the orogenic crust SSS in Central Asia.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

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