Browsing by Author "Miroshnyk, Vitalii"
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Item 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.Item 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.Item 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, VolodymyrENG: 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.