Browsing by Author "Miroshnyk, Vitalii"

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Controlling Stress State of a Hoisting Shaft frame in the Context of Specific Freezing Process
(НТУ « Дніпровська політехніка», 2018) Tiutkin, Oleksii L.; Petrenko, Volodymyr D.; Miroshnyk, Vitalii; Petrosian, Nataliia K.; Alkhdour, Ahmad M.
ENG: Purpose is to obtain regularities of a stress state of such multilayer system as neighbourhood rock mass – frozen soil – hoisting shaft frame in the process of numerical analysis to control a frame state with the selection of efficient parameters; thickness depending upon a specific frozen process specifically. Methods. Numerical analysis on the basis of a finite-element method has been implemented relying upon Pro Complex Structure CAD for Windows (SCAD) which made it possible to obtain stress state of a hoisting shaft frame and its interaction with ice-soil blocking as well as with neighbourhood rock mass soil. Findings. Hoisting shaft model has been developed. The model is based upon actual geometry and results of laboratory studies. Three blocking types (i.e. reinforced-concrete blocks, gray cast-iron tubbings, and modified gray castiron tubbings) and two soil types (i.e. sand and clayish soil at +8°С temperature) in terms of different freezing temperatures (i.e. (–2, –6 and –10°С) were analyzed numerically with the use of the SCAD. Results of the research have helped identify dependences concerning formation of a stress state of the multilayer neighbourhood rock mass – frozen soil – hoisting shaft frame system while varying properties of the listed types of a frame, neighbourhood rock mass, and ice-soil blocking. Regularities of the stressed state components deepening upon the frozen soil elasticity modulus, corresponding to its certain temperature, and elasticity modulus of a hoisting shaft frame have been obtained. The regularities connect changes in the stress of a hoisting shaft blocking in the context of specific freezing process. Originality. The obtained dependences of the stressed state of a hoisting shaft frame on the soil elasticity modulus and the material are composite spatial surfaces reflecting representatively the stressed state of such multilayer systems as neighbourhood rock mass – frozen soil – hoisting shaft frame. Practical implications. The regularities of the stressed state, determined for such multilayer systems as neighbourhood rock mass – frozen soil – hoisting shaft frame, make it possible to control stress components selecting rational geometry of a frame and its material or temperature cycle to freeze soils while applying the specific method.
Justification of Capital Repair of a Highway Bridge When Changing the Load
(Український державний університет науки і технологій, Дніпро, 2025) Miroshnyk, Vitalii; Tao, Mingzhu; Du, Xuanchen; Ivanchenko, V. S.
ENG: Purpose. The purpose of the scientific article is to substantiate the implementation of capital repairs of a road bridge that has been significantly damaged as a result of hostilities. The achievement of this goal is based on numerical analysis of the model using the finite element method, taking into account recommendations for reinforcing bridge elements. Methodology. Loads and impacts gathered during numerical analysis ensure the verification of bridge structures and elements for strength, stability, and durability according to the first group of limit states criteria, as well as stiffness and crack resistance according to the second group of limit states criteria. Temporary loads and impacts for structures calculating for all groups of limit states are taken with reliability factors for loads γf and dynamics factors (1+µ). The structure utilizes standard I-section beams for the superstructure with lengths of 22.16 m and 32.96 m, designed according to the working drawings and calculations developed by "International Design Institute" LLC and modeled in the professional structural analysis software Lira-CAD. Findings. The calculation of the beams was performed in two stages, reflecting their work: Stage 1 – Concreting the slab, the slab is not included in the structural analysis; Stage 2 – The slab is included in the span work, concreting of sidewalks without inclusion in the structural analysis, laying of asphalt concrete pavement, barrier railing, guardrails and expansion joints. The structure of the temperature-continuous monolithic slab, calculated using the Lira-CAD structural analysis software, has been reinforced considering the entire range of loads. Originality. The originality of the study lies in the scientific substantiation of carrying out major repairs on the bridge, which provides the possibility of the passage of temporary vertical loads according to H-30 and NK-80 schemes and pedestrian load on the sidewalks. Practical value. The practical value lies in the justification of the works on the restoration of the bridge design characteristics. Moreover, the calculations of the loads and impacts provide verification of the structures and elements of the bridge as well as the sequence of work operations during construction.
Nonuniform Stress State of a Hoisting Shaft Lining as a Result of Disturbance of the Ground Freezing Technology
(EDP Sciences, 2019) Tiutkin, Oleksii L.; Miroshnyk, Vitalii; Radkevych, Anatolii V.; Alkhdour, Ahmad M.
ENG: Abstract. The paper deal with the defining stress state of a hoisting shaft lining, lying in the sandy loam, when performing and disturbing the ground freezing technology. The relevance of the performed research lies in the fact that at nonuniform freezing or defrosting, nonuniform stress state is formed, which causes a significant over-stresses of the lining. To research the nonuniform stress state, a spatial finite element model of a hoisting shaft was developed, in which the case of nonuniform ground freezing was simulated. The calculation by the finite-element technique was carried out on the basis of the computational professional complex Structure CAD for Windows. In the course of the analysis, the values of stress state for linings made of reinforced-concrete blocks, B30 concrete, gray and modified castiron tubbings. A comparison of the components of stress state for sandy loam at a temperature of -2 °C (freezing), nonuniform freezing and at a temperature of + 8 °C (defrosting) was carried out. It was found that for the proposed geotechnical conditions in the form of soft, water-saturated sandy loam, it is recommended to use a lining made of gray and modified castiron tubbings.
Numerical Analysis of Stabilization Schemes for the Deformed State of Railway Embankment, Using Piles
(Óbuda University. Budapest, Hungary, 2025) Tiutkin, Oleksii L.; Kurhan, Mykola; Kurhan, Dmytro; Miroshnyk, Vitalii
ENG: This article presents a numerical analysis of stabilization schemes for the deformed state of a railway embankment using piles. The study involves the analysis of the concept of reinforcing the railway embankment with horizontal and vertical elements, as well as the main stabilization schemes for the deformed state. The objective is to select a stabilization scheme characterized by a minimal number of reinforcing elements that are sufficient to maximally reduce vertical displacements. For the numerical analysis, six finite element models were developed, which helped obtain the deformation results for the unreinforced embankment and five reinforcement options. Following the numerical analysis of the options with vertical and inclined reinforcement elements, the overall deformed state of the finite element model in the vertical plane was obtained. The results of vertical displacements of the reinforced railway embankment demonstrate that the installation of piles, created based on the jet grouting technology, reduces deformations by 1.50 to 1.88 times.
Regularities of the Strain State of the Embankment when Varying the Vertical Element Length of Strengthening
(IOP Publishing, 2024) Alkhdour, Ahmad M.; Tiutkin, Oleksii L.; Dubinchyk, Olha I.; Miroshnyk, Vitalii
ENG: The crisis that arose during the war in the transport system of Ukraine provided an opportunity to review the concept of integrating the Ukrainian railway into the European network. Corresponding changes, which require reconstruction of the railway, including track and embankment, have been analyzed. The railway embankment needs strengthening for its normal operation. The embankment reinforced with vertical elements, namely piles, has been studied. A finite-element model of the embankment, its soil base, and the rail-sleeper grid has been created. This model shows a vertical element of strengthening with lengths of 2.0, 4.0, and 6.0 m. The results of the numerical analysis are obtained, which makes it possible to analyze the values of horizontal and vertical displacements. The values of both components of the strain state are analyzed. The results of the analysis prove that strengthening with such elements has a maximally positive effect on both components of deformation. The regularities of changes in embankment displacements, when varying the vertical element length of strengthening, are linear. They prove that the presence of piles reduces the horizontal component by 1.1 ... 1.32 times, and the vertical one by 1.1 ... 1.24 times.
Substantiating Parameters of Short-Delay Blasting and Seismic Safety while Constructing the Inclined Tunnel
(IOP Publishing Ltd, 2022) Petrenko, Volodymyr D.; Bondarenko, Nataliia; Miroshnyk, Vitalii; Burskyi, Maksym; Konoval, Volodymyr
ENG: Implementation of blasting works in mining engineering and underground construction requires new effective blasting technologies in conducting an explosion. Short-delay blasting is a technology that requires scientific substantiation of its parameters. The application of explosion technology with increased blast intervals between charges is characterized as successful. However, the degree of reduction of seismic action and, accordingly, an increase in seismic safety needs clarification of the parameters of short-delay blasting. The scientific paper analyzes the delay time of the blast of charges and the classification of the degree of damage to buildings and structures. Seismic safety parameters for the inclined tunnel "Skhidnyi" while tunneling at the quarry of the Inhulets Ore Mining and Processing Plant (in the city of Kryvyi Rih) have been substantiated. The functional dependence of the maximum vibration velocity on the seismically safe distance has been obtained, as well as the dependence of the coefficient, the value of which characterizes the mass of the explosive. This allows for a quick evaluation of seismic safety parameters when calculating the parameters of blasting operations in the case of short-delay blasting.