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Загальна кількість знайдених документів : 5 Представлено документи з 1 до 5 |
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| 1. | 
Prykhodchenko V. F. Effect of time-transgressive faults upon methane distribution within coal seams [Електронний ресурс] / V. F. Prykhodchenko, О. О. Sdvyzhkova, N. V. Khomenko, V. V. Tykhonenko // Науковий вісник Національного гірничого університету. - 2016. - № 1. - С. 31-35. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2016_1_6 Problem solution of efficient methane extraction in coal deposits depends on analysis of their distribution conditions within coal-bearing thickness. Tectonic structure is the most important factor of methane redistribution and retaining within coal-bearing thickness in terms of Western Donbas. Purpose. To determine the effect of tectonic faults of various types and occurrence period upon methane redistribution for the purpose of its efficient extraction. Methodology. Collection, analysis, and generalization of the measuring results of coal seam gas bearing capacity in geological prospecting wells using KA-61core extractor as well as mapping of gas bearing capacity and its derivatives using approximation polynom of three initial stages within the walls of tectonic faults of various types with their following analysis were the methodological basis for the study. Findings. Methane-bearing characteristics of coal seams within the walls of high-amplitude, consedimental, medium-amplitude postsedimental and low-amplitude fault have been analyzed. Maps of local gas-bearing capacity deviations have been developed to demonstrate the effect of these tectonic faults upon localization of methane accumulations. Originality. Effect of various faults as well as methane redistribution within coal seams of Western Donbas has been analyzed for the first time. Practical value. The data of core extractor measuring can be used to analyze the effect of tectonic fault upon coal seam methane-bearing characteristics. The analysis of the developed maps in terms of undetermined fault type allows assuming the time of fault formation as well as the character of its effect upon methane redistribution. | ||
| 2. |
Sdvyzhkova О. О. Determination of the displacement of rock mass nearby the dismantling chamber under effect of plow longwall [Електронний ресурс] / О. О. Sdvyzhkova, D. V. Babets, K. V. Kravchenko, A. V. Smirnov // Науковий вісник Національного гірничого університету. - 2016. - № 2. - С. 34–41. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2016_2_8 Purpose. Determining the increase of rock displacements nearby a pre-constructed dismantling chamber while a plow longwall approaching. Additional goal is to develop a technique for estimating the pressure created by failed rocks at different stages of mining. Methodology. Displacements around a pre-constructed dismantling chamber were studied in situ using tell-tale stations. Numerical simulation was carried out to determine the rock stress-strain state applying a plastic deformation model. The numerical procedure of strain accumulation was implemented at the sequential change of mined-out space while modeling. Areas of broken rocks (failure zones)were determined according to Hoek - Brown strength criterion. Numerical simulation was carried out concerning different geological conditions and excavation dimensions. The non-linear estimation method combining with multiple regression and variance analysis were used to build general regularities. Findings. The multi-variant calculations of stress-strain state change were carried out for different values of rock strength, coal seam thickness, mining depth and dismantling chamber size as well. The results were generalized for different geological conditions. The failure zone height and excavation contour displacements are represented as a function of factors mentioned above. Originality. New regularities were obtained relatively the increase of rock displacements nearby a dismantling chamber. A failure zone spreading was shown depending on rock properties. Convenient techniques were developed to calculate constitutive geomechanical characteristics and provide an adequate support design for dismantling chamber under various mining and geological conditions. Practical value. The set of formulas derived with regression method allows determining the main geomechanical characteristics and gives a simple technique to design the support of dismantling chamber. This is a background for developing the general standards related to dismantling chamber designing under Western Donbass geological conditions. | ||
| 3. |
Babets D. V. Estimation of rock mass stability based on probability approach and rating systems [Електронний ресурс] / D. V. Babets, О. О. Sdvyzhkova, M. H. Larionov, R. M. Tereshchuk // Науковий вісник Національного гірничого університету. - 2017. - № 2. - С. 58-64. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2017_2_10 Methodology. Different types of rock mass classifications are analyzed and discussed. Advantages and disadvantages of rating systems are clarified to improve the system based on the structural factor. Statistical strength theory is used to determine the structural factor considering rock mass heterogeneity. A correspondence is set up between the structural factor and the factors reducing computed strength of rock mass obtained using Hoek-Brown's and Palstrom's approaches. Findings. Quantitative comparison of the structural factors which approximate laboratory strength evaluation to real rock mass strength and are based on different approaches is carried out. This allowed comparing the different classifications of rocks and conducting geomechanical calculations using alternative methods. The correspondence between structural factor and geological strength index is specified. This provides a possibility of designing mining excavations using a good proven generalized Hoek - Brown strength criterion considering natural and technogenic disturbance of rocks. Originality. For the first time the structural factor is represented as a piecewise monotonic function. The relationship between structural factor and Geological Strength Index and Rock Mass Index classifications for geomechanical calculations is established. The significant influence of discontinuities and the type of filler between joints on mechanical properties of a rock mass is shown. The need of considering the discontinuity surface conditions while structural factor defining is clarified. Practical value. The relation between structural factor and Geological Strength Index allows creating the technique for application of GSI rating system and Hoek - Brown failure criterion in excavation design in terms of Ukrainian mines. | ||
| 4. |
Sdvyzhkova О. Effect of harmonic oscillations on a crack initiation in the rock mass [Електронний ресурс] / О. Sdvyzhkova, Yu. Golovko, D. Klymenko // Науковий вісник Національного гірничого університету. - 2017. - № 4. - С. 13-18. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2017_4_4 Purpose. The purpose is to improve, develop and generalize the criterion of a crack initiation taking into account the simultaneous effect of the rock stress state and oscillatory processes. The influence of the oscillation amplitude-frequency characteristics on the critical crack length has to be studied as well. Methodology. The methodological basis of the problem solution is a comprehensive approach that includes the mathematical analysis, numerical methods for solving transcendental equations, analysis of the results in the mathematical package Mathcad. Findings. A crack initiation criterion has been developed considering both static stresses (tensile and compressive) and dynamic stress in an elastic wave spreading in the rock mass. The critical length of the initiated crack is determined depending on oscillation amplitude and frequency, static stress and rock crack resistance. The abrupt change in the critical crack length is defined as an indication of the dynamic rock failure. The values of oscillation frequency provoking a decrease in the critical crack length and dynamic rock failure are determined for different rocks. Originality. New approach is used to describe the rock destruction considering the elastic oscillations in the rock mass. The criterion of a crack initiation has been generalized to consider the action of both tensile and compressive stress near by the crack and harmonic stress in an elastic wave. So, based on a common time-space failure criterion, we take into account the stress which is a sum of quasi-stationary and harmonic components. In this paper we focused on the critical crack length that provokes the crack initiation. The influence of oscillation amplitude and frequency on critical length altering has been estimated for different values of the crack resistance. Practical value. The results obtained in the study of criterion crack initiation, can be used to improve the acoustic forecast of gas-dynamic phenomena by the amplitude-frequency characteristics of oscillations. For this purpose, we defined ranges of harmonic oscillation frequencies in some rocks (fine-grained sandstone, limestone, siltstone, coal) in which the initiating of "short" cracks occurs. And we got the real conditions (for coal), in which a slight change in the oscillation amplitude in the array of rocks leads to a jump in the length of the cracks. | ||
| 5. | 
Sdvyzhkova О. Studying a crack initiation in terms of elastic oscillations in stress strain rock mass [Електронний ресурс] / О. Sdvyzhkova, Yu. Golovko, M. Dubytska, D. Klimenko // Mining of mineral deposits. - 2016. - Vol. 10, Iss. 2. - С. 72-77. - Режим доступу: http://nbuv.gov.ua/UJRN/rr_2016_10_2_12 | ||
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