Кафедра "Мости та тунелі"(з 2016 року об’єднано каф. "Мости" та каф. "Тунелі, основи та фундаменти") <br> (з 2021 року ввійшла до складу кафедри "Транспортна інфраструктура")

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ENG: Department of "Bridges and Tunnels"(since 2016 merged the department "Bridges" and the department "Tunnels, foundations and foundations")
(since 2021 became part of the Department of "Transport Infrastructure")

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Actual Problems of Interaction of Objects of the Infrastructure and Rolling Stock
(Transcomp – XV International Conference, 2011) Kulyabko, Vladimir V.; Raspopov, Oleksandr S.; Artyomov, Vitaliy Y.; Artomov, Vitalii Y.; Artyomow, V. E.
EN: There are a number of actual problems of modern bridge construction in a context of static-dynamic interaction of bridge designs and the railway rolling stock is considered. The integrated classification of settlement models for research of joint dynamics of system "bridge-train" is offered, the basic criteria and the factors influencing result of numerical modeling and dynamic calculation of bridges are allocated.
Analysis of the Differences of the Results of Calculations of the Stability Coefficient of the Landslide Slope
(Дніпровський національний університет залізничного транспорту ім. В. Лазаряна, Дніпро, 2019) Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Ihnatenko, Dmytro Yu.
ENG: Purpose. Improving the accuracy of determining the stability of landslide slopes in some cases requires the use of several methods to find the coefficient of stability. Therefore, it is necessary to analyze the discrepancy between the results of the calculation of the coefficient of stability of landslide slopes. Methodology. The solution to the problem of finite element slope modeling in the LIRA-SAPR 2016 software package is based on the creation of a spatial finite element model. With its help, the nonlinear problem of geomechanics was solved with the introduction of special finite elements, which simulates the work of the soil. As a reference, the coefficient of stability was calculated by the round-cylindrical sliding surface method. Landslide slope in the software package «OTKOS» was creat-ed and calculated. Results. The results of the calculation of the finite element model of the landslide slope in the LIRA-SAPR 2016 software package were obtained. The value of the coefficient of stability of the landslide-hazardous section of the slope in the «OTKOS» was obtained using eight methods. The calculation results in the «OTKOS» are compared with the coefficient of stability determined by the method of a circular-cylindrical sliding surface. Originality. The results of the calculation of the coefficients of stability in the «OTKOS» allowed us to divide the curves of the sliding surface into two groups: that which do not belong to circular-cylindrical, and that which satisfy the results of finite element modeling. Practical value. After a series of calculations and after analyzing the results, it turned out that not all methods equally solve the problem of the stability of landslide slopes. This is due to the different limitations of each of the methods, so as a criterion for the adequacy of the results obtained, it is necessary to analyze the magnitude of the discrepancy between the obtained values of the coefficient of stability.
Analysis of the Problems of Sections With the Transitional Rigidity Indicator in World Bridging
(Дніпровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2019) Marochka, Vitalii V.; Boboshko, Stepan H.
EN: Purpose. To analyze the problem of areas with a transitional stiffness on the approaches to the bridges based on the experience of European and American bridge-building. To find out the root causes and methods for detecting track defects in transitional stiffness zones. To propose a pilot model for the development of transitional stiffness areas based on the experience of developed countries in Europe. Methodology. Collection of data on the causes and nature of the occurrence of bumps on approaches to bridges based on the experience of specialists in the design, construction and operation of railway and highway bridges. Analysis of methods of arrangement of transition areas on approaches to bridges in European countries. Results. An analysis of the literary sources of developed countries of the world on the problem of the origin and methods of detection of bumps in areas with transitional stiffness on the approaches of bridges was performed. The results were collected on ways to identify problems in areas with transient stiffness and how to solve them. A model for mathematical and experimental studies was proposed. Origi-nality. Scientific interest is that, despite the extensive experience of developed countries of the world, the Ukrainian norms still do not have a clear mechanism for identifying and characterizing problems of track geometry in sections with transitional stiffness. Thus, studying the experience of more advanced countries in the field helps to con-sider the problem more clearly and standardize its definition. Practical value. If proposed model of reinforcement of transition stiffness areas will be confirmed it allows to reduce the cost of maintaining of the track and to solve the problems of the transitional areas at the stage of bridge construction, that is, before its immediate occurrence.
Application of Centrifugal Modeling for the Study of Landscape Structure Stability
(Tamilnadu, India, 2019) Ignatenko, D. Yu.; Tiutkin, Oleksii L.; Petrenko, Volodymyr D.; Alkhdour, Ahmad M.
ENG: The calculation of stability by mathematical methods of complex shapes of slopes with a diverse geological structure is reduced to simple formulations and assumptions for finding curves of sliding surfaces and for forecasting possible forms of stability loss. The method of centrifugal modeling allows us to conduct in-depth studies of the experimental, reproduced, reduced scale of the slope and to reliably identify the nature of the existing deformations after rotation on a centrifuge, analyze them and draw conclusions about the stability of the studied slope. The centrifugal simulation can be divided into four stages, each of which is described in detail in this article with reference to photo materials and descriptions. The obtained results of the centrifugal modeling of the shifting slope of the Krasnopovstanska ravine and the analysis of the deformed state of the model before and after placement of soil cement piles in the body of the slope. Centrifugal modeling is not a new method for studying the stability of slopes. This method requires special complex hardware and hardware, therefore, it is used rather infrequently. Conducting this type of research is accompanied by a small amount of informative literature on the methodology of the simulation itself. This article is devoted to the question of conducting and successfully using the method of centrifugal modeling of landslide slopes with the observance of certain features. Application of the technique of centrifugal modeling allows solving problems of calculating the stability of natural slopes with complex geological structure
The Application of Injection - Grouting for Strengthening of the Weak Subgrade Foundations
(PGASA, 2014) Petrenko, Volodymyr D.; Sviatko, Ilona O.; Yampolskyy, D. O.
ENG: This article analyzes the features of the subgrade construction on soft soils, and offers to use injection–grouting technology, which is widely used abroad, but needs official regulations for the application in observed area.
The Application of Injection - Grouting for Strengthening of the Weak Subgrade Foundations (preprint)
(PGASA, 2014) Petrenko, Volodymyr D.; Sviatko, Ilona O.; Yampolskyy, D. O.
ENG: This article analyzes the features of the subgrade construction on soft soils, and offers to use injection–grouting technology, which is widely used abroad, but needs official regulations for the application in observed area.
Changing the Stress State of the Track Superstructure while Strengthening the Subgrade
(VŠB – Technical University of Ostrava, 2020) Tiutkin, Oleksii L.; Neduzha, Larysa O.; Kalivoda, Jan
ENG: Strengthening the subgrade with the help of various technologies significantly affects the stress state of the track superstructure. The strengthening of the subgrade with piles, leads to an abrupt stiffening of the track superstructure, which is problematic for its normal operation. Two finite element models were created to determine the change in the stress state of the track superstructure when strengthening the subgrade. They fully reflect the geometric, deformation and power characteristics of a real subgrade, which is strengthened by piles. Individual finite elements of the models are provided with the deformation characteristics of the steel rails, reinforced concrete sleepers, soil subgrade, ballast and soil-cement material of piles. The authors carried out the calculation of stress state of the track superstructure for two finite element models. Results are obtained and analyzed to help in choosing the most effective option for strengthening the subgrade.
Comparative Analysis of Calculation Results of Supporting Structure of Soil-Cement Piles
(Kaunas University of Technology, Kaunas, 2019) Pshinko, Oleksandr M.; Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Andrieiev, Volodymyr S.; Hubar, Oleksіy V.; Ihnatenko, Dmytro Yu.; Markul, Ruslan V.
ENG: Abstract. The article presents the results of comparison of the stress-strain state of 4 models of a retaining wall structure of soil-cement piles on a landslide-prone slope. This study compares the changes in the stress distribution and displacements in the model elements of the retaining structure of soil-cement piles depending on the design parameters and the method of piles location in the body of the soil mass. The comparison of models of supporting structures of soil-cement piles on a landslide-prone slope allowed obtaining: –the comparative analysis of the quality work of individual elements of the supporting structure for strength and deformation in a three-dimensional representation; –the comparative assessment of the performance of the supporting structure of soil-cement piles on a landslide-prone slope; – histograms of dependences of changes in the angle of piles inclination to the vertical axis of their holding force, strength and deformation of the slope;
Comparative Analysis of the Parameters of the Strength of the Subgrade at the Transition to the Higher Axial Loading up to 25 t
(IOP Publishing, Kharkiv, 2019) Radkevych, Anatolii V.; Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Andrieiev, Volodymyr S.; Mukhina, Nataliya
ENG: Abstract. A review of the scientific and technical literature on the re-alignment of the route during the transition to high axial load from the accepted today (23.5 t / axis) to the perspective (25 t / axis) shows that in the stage of preliminary researches imitation modeling of the earth web by the finite element method (ITU) as the most convenient, accurate and illustrative of the known numerical methods. In order to provide recommendations on the strength of the subgrade when moving to a higher axial load up to 25 t / axis, an analysis was conducted, the essence of which was to compare the stress-strain state of the subgrade at two loads per axis: 23.5 t / axis (existing ) and 25 (perspective). All the geometric and deformation characteristics of the formation are taken from data on a two-track section with a height of embankment of 3. The deformation characteristics are chosen so that the working material of the formation is in accordance with the average indices of deformation capacity of the railways used. The ITU train load calculus makes it possible to obtain all the factors of VAT in it, which is the main purpose of the study of the strength of the earth cloth, and allows to forecast their development in the future.
Comparative Calculation of the Stability of the Landslide Slope in the Software Complexes «OTKOS» and «LIRA-CAD 2017»
(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2018) Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Ihnatenko, Dmytro Yu.; Kovalchuk, Vitalii V.
ENG: Purpose. The analysis and comparison of the results of calculation by the finite-element model of the slope in the software complex «LIRA-CAD 2017» with the determination of the its stability in the software complex «OTKOS» allows to determine the accuracy the results and the most favorable conditions for the development of the displacement and parameters of the most dangerous surface slip for further calculation of anti-slip retaining structures. Methodology. The geomorphological data were obtained from the results of laboratory studies of soils in the considered slope. Creation of a bulk finite element model of the slope in accordance with the built cuts and depths of soil layers. Calculation of the nonlinear problem of finite-element simulation of the slope in the software complex «LIRA-CAD 2017». Creation and calculation of the stability problem of the landslide slope in the software complex «OTKOS» and comparison of the results of the its stress-strain state. Results. The results of calculating the finite-element model of the landslide slope in the software complex «LIRA-CAD 2017» and its stability in the software complex «OTKOS» were obtained. The analysis of the obtained results of sliding surfaces study is carried out. The calculation of the strengthening of the slope area is carried out with the help of soil cement retaining piles, located at right angles to the vector of the displacement direction. Originality. Despite the presence of a large number of different methods of studying the surfaces of sliding, it is impossible to determine exactly the scenario of the displacement, using only one of the calculation methods. First of all, this is due to the rather high variation of the initial data of the problem, which in turn depends on the environment and assumptions, as well as on external factors that can not be taken into account precisely. The next task is to carry out the calculation of the strengthening of the landslide slope by soil-cement piles. Practical value. It is known that it is advisable to use soil-cement piles as a protective element, which interacts well with the soil environment due to its structure of the source material. A comparative analysis of the calculation results of the slope stability with the help of software systems «LIRA-CAD 2017» and «OTKOS» gives an answer to the question of the its reliability.
Complex Analysis of Subgrade Stress-Strain State with Combined Strengthening
(Полтавський національний технічний університет імені Юрія Кондратюка, Полтава, 2017) Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Sviatko, Ilona O.; Alhdur, A. M. M.
ENG: The paper highlights combined techniques of strengthening that include geotextile laying as well as other related advanced technologies. Subgrade construction analysis and its modification, reinforced with the different types and options of combined strengthening were conducted. To justify strengthening of subgrade a series of numerical calculations were made. Simulation with software package SCAD has confirmed the experimental results. From obtained results one can conclude that minimum horizontal displacements are observed in the version with deepening of geotextile at 1m and vertical ones at 0.4 m. Based on simulation results it is possible to make recommendations concerning modernization of existing subgrade and construction of new one in complex engineering-geological conditions.
Comprehensive Analysis of the Retaining Pile Structure with the Determining the Stability Factor by Numerical Methods
(EDP Sciences, 2019) Dubinchyk, Olha I.; Petrenko, Volodymyr D.; Ihnatenko, Dmytro Yu.; Kildieiev, Vitalii R.
EN: Abstract. The paper highlights the results of the complex analysis of the retaining pile structure with determining the stability coefficient by numerical methods. To achieve this purpose, after designing a structure with jet grouting piles, the research of the stability coefficients of the landslide hazard slopes in the software complex "OTKOS" and its stress state in the software complex LIRA-CAD system was conducted. The relevance of the completed research is to develop rational parameters of the pile structure. A comparison of determining the stability coefficient of a slope by different methods for the existing landslide stretch for the public roadways of local significance С141017 (Lviv-Shehyni) – Sudova Vyshnia was carried out. Originality of the paper lies in the fact that to determine the stability coefficient in the model, the layeredness of the slope under study is taken into account, and the nonlinear volumetric problem is solved in the course of the numerical analysis of the stress state. The rational distance between piles in the gap and the length of the pile under a certain percentage of cement and ground was justified.
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.
Determination of the Size of Theseal Zone and the Soil Pressure on Underground Communications in the Process of Soil Deformation by the Wedge-Shaped Tip
(НВП ПП «Технологічний Центр», Полтавська державна аграрна академія, 2018) Posmituha, Alexander; Kravets, Svyatoslav; Suponyev, Vladimir; Kulazhenko, Yevhenii Yu.
EN: The object of the study is a working element with a wedge tip for static perforation of the soil with the laying of several cases for underground utilities. One of the problems that require research is the laying, location and proximity of various types of underground utilities, laid trenchless way. The study of the zone of influence of working bodies on the ground and communication will give us the opportunity to more efficiently design the use of underground space, to reduce the risks of damage to or destruction of communications and reduce the cost of the work. Studies are based on the law of conservation of mass before and after compaction of the soil with a wedge tip and on the basic theories of soil mechanics. This allows you to determine the pressure of the soil on the working element and on the communication, located nearby. The result obtained in the work shows that the pressure value is not the same in different directions of the wedge working element. It is also proved that the number of cases, which are simultaneously laid, have little effect on the zone of elastic-plastic deformation of the soil. These effects make this form of hole indispensable when you need to simultaneously lay several, more than 3, cases, compared to the traditional conical-cylindrical tip. To determine the soil pressure on underground utilities were used only the size of the working elements, and data that are easy to determine – the type and density of soil, humidity, porosity and other standardized characteristics. The use of this method has a significant advantage over other methods, which are based on empirical relationships that are either difficult to determine or their reliability is questionable. Due to the reduction of the cross-sectional area of the deformable soil, the wedge working body is indispensable for stretching the group of cases.
Determining the Influence of Physical Nonlinearity of Soil Strength Properties on the Estimated Base Resistance
(Private company "Technology center", 2019) Shashenko, Oleksandr; Shapoval, Volodymyr; Kovrov, Oleksandr; Skobenko, Alexandr; Tiutkin, Oleksii L.; Babii, Kateryna; Samorodov, Oleksandr; Slobodyanyuk, Sergey
ENG: The paper has examined the potential of using nonlinear models of strength in determining the initial critical load on soil, as well as the standardized and estimated base resistance, which makes it possible to reduce labor intensity in the process of determining the strength properties of soils.Based on the analysis and generalization of results from theoretical studies into geomechanical processes using analytical mathematical methods, the formula modifications have been derived that are intended for determining the initial critical load on soil, as well as the standardized and estimated base resistances.We have established interrelation between strength, in particular specific cohesion, and the angle of internal friction, which are included in the strength conditions by Mohr-Coulomb and A. Shashenko, thereby making it possible to improve the procedure for calculating external loads on soil.The dependences of critical loads on base on the mean pressure under the sole of the foundation haven been analyzed in the range of pressure Р = 100...500 kPa using the strength conditions by Mohr-Coulomb and A. Shashenko.It has been established that when using generally accepted estimation formulae to determine the critical loads on base, it is required that the pressure range should be taken into consideration at which the properties of soil strength were determined. In this case, using the Shashenko failure criterion to determine critical loads on base makes it possible to properly consider the impact exerted by the mean pressure on them under the sole of the foundation.In contrast to dependences used currently in the Ukrainian, Belarusian, Russian regulatory documents, as well as in other countries’ standards, the resulting formulae make it possible to take into consideration the dependences of soil strength properties on the mean pressure on soil under the sole of the foundation. The results obtained make it possible to improve the reliability of determining the initial critical load on soil, as well as the standardized and estimated base resistances. This is achieved by taking into consideration the nonlinearity of the Mohr limiting circles’ envelope using the strength condition by A. Shashenko.
Development of Technology of Arranging Areas with Transitional Stiffness Index on Approaches to Railway Bridges
(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2018) Marochka, Vitalii V.; Boboshko, Stepan H.
EN: Purpose. To investigate the issue of transitional rigidity on the railways of Ukraine, to form a complex of existing measures to strengthen the transitional sections, to develop and justify the solution to the problem of transitional stiffness on approaches to railway bridges. Methodology. Theoretical research methods analysis and synthesis has been used. For mathematical modeling of the structure, a finite element method has been used - a three-dimensional mathematical model was created with stiffnesses corresponding to real ones, and loaded by static load of the rolling stock. Findings. The analysis of the literature and the experience of developed countries on the issue of arranging areas with transitional stiffness index on approaches to railway bridges, proposed and developed a solution for amplifying sections with transitional stiffness, a theoretical calculation of the mathematical model of the corresponding areas was developed the working draft for arranging areas with transitional stiffness index on approaches to railway bridges has been designed. Originality. The technology of amplification of areas with transitional stiffness has been proposed, a model of a section with a transitional stiffness index has been developed and constructed in the first approximation. Practical value. Developed construction of soil-cement piles allows to enhance areas with transitional stiffness index on approaches to railway bridges. The obtained data open up new possibilities in the experimental study of areas with a transitional stiffness index.
Devising a Procedure for Assessing the Subgrade Compaction Degree Based on the Propagation Rate of Elastic Waves
(РС Тесhnology Сеntеr, Kharkiv, Ukraine, 2021) Kovalchuk, Vitalii V.; Kravets, Ivan B.; Nabochenko, Olga S.; Onyshchenko, Artur; Fedorenko, Olexander; Pentsak, Andriy; Petrenko, Oleksiy V.; Hembara, Nataliya
EN: This paper reports the analysis of the methods for estimating the technical condition of the subgrade underneath a constructed railroad track or road during its operation. The study results have proven that the issue related to monitoring and controlling high-quality compac-tion of a heterogeneous subgrade remains relevant and requires the construction of reliable experi-mental methods for assessing the subgrade degree of compaction.A procedure for determining the compaction of subgrade in the laboratory has been devised, based on inertial microcomputer technologies, which makes it pos-sible to assess the degree of com-paction of subgrade soils depend-ing on the propagation rate of an impact's elastic waves.An experimental study has been performed into the propaga-tion rate of elastic waves across a homogeneous subgrade made of coarse-grained sand and a hetero-geneous subgrade made of coarse sand with a layer of clay in the middle of the prism. The study results established that the propa-gation rate of an elastic wave in a heterogeneous subgrade accepts a lower value than the rate of wave propagation in a homogeneous subgrade.Through the dynamic inter-pretation, by using a discriminant statistical analysis, the character-istic features have been defined in the distribution of accelerations in the body of the homogeneous and heterogeneous subgrade, depend-ing on the degree of compaction, which would make it possible to monitor the state of the subgrade during operation. As the degree of the subgrade soil compaction affects the technical condition of roads.
Dynamic Behavior of Two-Span Continuous Concrete Bridges under Moving of High-Speed Trains
(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Marinichenko, Oleksii H.
EN: Purpose. The scientific work provides a comparison of the results of the movement of a high-speed passenger train across the bridge, obtained as a result of finite element modeling in the SAP2000 software package, and real tests of a double-span concrete railway bridge. Analysis of the rigid characteristics of flying structures. Methodology.The numerical method presented in this study shows valid results concerning the dynamic analysis of the behavior of bridges in conditions of high-speed train traffic. The factors influencing the dynamic behavior of bridges under moving loads, the influence of design parameters and rolling stock, as well as the interaction of the train and spans are determined. The system was used in the form of moving concentrated forces simulating the axes of the train. Findings. Maximum movements and accelerations were obtained as a result of the dynamic calculation for different speeds of the train and compared with practical tests. The correctness of the model of a span structure with regard to continuous ferroconcrete spans was verified. Originality. Within the framework of the work, the latest test results were used, including those with speeds calculated on the prospect of rail passenger traffic. For these tests, a model of a span structure was developed. Practical value. The results of the research can be used to plan the introduction of high-speed train traffic on existing and planned flying structures of reinforced concrete bridges. An approach to the design of span structures that will be effective when passing high-speed passenger trains is implemented.
Dynamics of Reinforced-Concrete Spans with Railway Track Eccentricity (preprini)
(Rigas Tehniskas Universitates Dzelzcela Transporta Instituts, 2011) Raspopov, Alexander S.; Rusu, Sergey P.; Artyomov, Vitaly Ye.
EN: Significance effects of railway track eccentricity on railway span vibration character by locomotive moving with various speeds are investigated. The mathematical model of the eccentricity of a railway track on the span of railway bridges is proposed. The dynamic analysis of three-dimensional girder systems based of the Newton-Euler differential nonlinear equations modeling aspects are represented.
Estimation of Subgrade Strengthening Influence Using Soilcement Elements
(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2016) Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Sviatko, Ilona O.
ENG: Purpose. The aim of this work is to identify dependencies and options to strengthen the roadbed and a weak base by grouting piles. Analysis of software package SCAD to assess the effect of the selected option of strengthening the construction of spatial subgrade models. Methodology. In this paper the method of calculation of the soil mass in the software package SCAD is considered, which is a universal accounting system of finite-element analysis of structures and is focused on solving problems of designing buildings and structures rather complex structure. The finite element method is among the most modern and effective methods for the calculation of structures for various purposes. In the simulation, we get a complete picture of the stress-strain state of the study area, as well as the value of the limit load, rainfall, and so on. The spatial model based on the finite element volume, to better address the real characteristics of the soil mass, meets all the geometric characteristics of size and natural subgrade and the top structure the path that has been adopted in Ukraine. Findings. It was found that the most effective option to strengthen the roadbed, when applying grouting piles at the base of the subgrade and body, is to strengthen the five piles. At the same time there is even strengthen the soil mass at the level of 25 … 30% of the entire depth. However, even with the strengthening of the only two piles at the base of the effect of the strengthening of 14.1%. Established equation is linear and describes the decrease in strain. Taking into account the results of the research can be concluded that the consolidation is proportional to the depth with any number of piles. The dependence of the strain on the number of piles adheres to a polynomial function. Strengthening the bases of the subgrade and body depth also occurs in proportion with any number of piles. Originality. Design scheme generation algorithm for the calculation of the subgrade on a weak basis by finite element method was determined. The selection of strength characteristics of soils and the design parameters for use during the numerical simulation was completed. Load process simulation of the system by rolling stock was grounded. Practical value. Analysis of stress-strain state of «weak base-subgrade» allows you to see the basic laws work the soil and take the necessary measures to enhance the cross-section profile of jet-grouting elements.
Features of Drilling-and-Blasting at Construction of Beskidskiy Tunnel
(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2016) Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Proskurnia, S. T.
ENG: Purpose. In this article it is necessary to analyze the possibility of developing technology and increasing its efficiency during the Beskidskiy tunnel construction in difficult engineering and geological conditions. Methodology. The authors have performed analysis of the technological level of mining and construction works, new technique, equipment and production. One of the important issues of blasting operation is to ensure the seismic safety, acting at a distance of 30 m in the axes of single-track tunnel, as the distance to it will be 20 m from the nearest charge in the laying tunnel. This problem was solved by applying the combined blasting of blast-hole charges with delay-action and long-delay ways. Herewith the total mass of charges in the stope was divided into three groups, in which the first group is exploded by short-delay firing with, and the second one is exploded by shortdelay firing too with intervals of 200…400 ms, the third is exploded by long-delay blasting at intervals of 500…10000 ms. The combined blasting of short-delay charges and delay action ones let significantly reduce seismic action at a mass explosion of charges when driving of double-track railway tunnel of a large cross-section. Findings. The paper presents the developed technology model, describing dependence of the machines from engineering and geological conditions. The methodology of drilling and blasting works at the construction of the tunnel callote and stross as well as a technique of arrangement determination and intervals of shot-delay and delay blasting of blasthole explosive charges was developed. Maximum permissible concentration of gases and vapours at blasting was presented. The calculations showed that the maximum level of gas contamination of the working area in Beskidskiy tunnel is achieved at blast operations. In accordance with this ventilation of the tunnel when driving is carried out by independent systems with mechanical ventilation by blowing using mine fans of special mining enterprises. Originality. The developed seismically safety charge masses are based on the well-known state about antiseismic blasting regulations. Practical value. The authors proposed and grounded the efficient technology for reduction to practice of drilling and blasting works (with dividing of the tunnel cross-section into the calotte and stross during of the Beskydy high-mountain tunnel construction. The results of technological experiment are presented.
Geotechnical Analysis of Optimal Parameters for Foundations Interacting with Loess Area
(EDP Sciences, 2020) Dubinchyk, Olha I.; Bannikov, Dmytro O.; Kildieiev, Vitalii R.; Kharchenko, V.
EN: The article highlights results of the geotechnical analysis of the stress and strain state for the base of a subsoil massif under its interaction with the strip foundations. The massif is represented by loess soils which while soaking give overtime subsidences that complicate the operation of a building or a structure. Through geotechnical iterative research, optimization of the parameters for strip foundations on four axes at a four-storeyed residential building is carried out. Checks are performed on two groups of limiting states for scenarios of soil occurrence in natural, moistened and compacted states. The optimum dimensions in the width of strip foundations are selected, they give approximately the same strain values of the base after the creation of the soil bedding with its layer-by-layer compaction. The relevance of this research is to develop optimal parameters in the design of strip foundations for shallow depth on subsidental loess soils.
Improving the Safety of Railway Subgrade When it is Strengthened Using Soil-Cement Elements
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Krysan, Vitalii; Krysan, Volodymyr; Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Andrieiev, Volodymyr S.
ENG: Abstract. The article identifies the main parameters of the drilling-mixing technology, which is the most effective in fixing weak soil bases during the construction and restoration of transport, industrial and civil structures. The difference of the technology developed by the authors is that the strengthening process is carried out at low pressure (0.15 ... 0.25 MPa). The relevance of the research is that the proposed technology requires less cost with high rates of restoring the strength of soil foundations. To prove the high quality of the technology, laboratory studies were carried out to determine the optimal characteristics of the soil-cement element, as well as the proportions and composition of the fixing solution. The dependences of the strength of soil-cement elements in the air-dry condition with cement content from 7% to 23% with water-cement ratio in solution 1 / 0.3 and with cement content from 13% to 37.5% with water-cement ratio in solution 1/0,6. During the experimental-industrial studies of the author's technology, the embankment was constructed with the soil-cement-reinforced elements for the access road approaches at one of the facilities in Kirovograd region, which ensured safety in the operation of a complex transport structure.
Interaction of Soil-Cement Pile Supporting Structures with the Body of a Landslide
(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Ihnatenko, Dmytro Yu.; Petrenko, Volodymyr D.; Tiutkin, Oleksii L.
ENG: Purpose. Analysis and comparison of the landslide slope finite element model calculation results of the appliance of soil-cement piles, depending on the variation of the retaining structure rigidity, makes it possible to evaluate the effectiveness of their application and the cooperative work of piles with the displacement body. It also makes it possible to make a conclusion about the advantages of using this anti-landslide protection method of the slope. Methodology.Analysis of geomorphological data obtained from the results of laboratory studies of soils on the slope section is considered. Creation of a three-dimensional finite-element slope model according to the constructed sections and depths of the soil layers. Calculation of the nonlinear problem of finite element modeling of the slope with applying of soil-cement piles of various rigidity. Findings. The obtained results of calculating the finite element model of the landslide slope, and the analysis of the stress-strain state of the construction with soil-cement piles has been carried out.Originality. Despite the widespread of using soil-cement piles as enclosing structures for the construction of foundation pits and reinforcement of foundations of emergency structures, special attention should be paid to the study of the expediency of using soil-cement retaining pile structures on landslide areas. Practical value. It is known that soil-cement retaining piles are expediently in use as a protective element, which interacts quite well with the ground environment due to its structure of the initial material. Using of modern computer programs of finite element modeling makes it possible to calculate the efficiency of the use of soil-cement piles and to determine the parameters of the necessary retaining structure according to the given geological structure of the slope, and also, depending on its shape and the physical characteristics of the soils, to compare the performance of different protective landslide structures types.
Investigation of the Operation of the Railway Track with Reinforced Concrete Sleepers in Curved Sections with Radius R ≤ 350 m
(Printing House “Technologija”, Kaunas, Lithuania, 2020) Markul, Ruslan V.; Hubar, Oleksіy V.; Arbuzov, Maxim; Andrieiev, Volodymyr S.; Tiutkin, Oleksii L.; Savyts’kyy, V.; Ganich, Ruslan Ph.
ENG: The article presents the results of the research on polygon extension for laying reinforced concrete sleepers under difficult conditions (R≤350 m, mountainous terrain) with ensuring safety traffic and reliable operation of the railway track. Changes in the geometry of the track in the plane with wooden sleepers and Д0 fastener as well as reinforced concrete sleepers with СКД65-Б fastener in the curve with the radius of 350 m were investigated. The results of the research allowed to obtain: - method and algorithm for determining the tapping section of the track gauge extension on reinforced concrete sleepers in curves with radius R ≤ 350 m; - comparative assessment of the track gauge change with the use of Д0 fastener (wooden sleepers) and СКД65-Б fastener (reinforced concrete sleepers) in curves with a radius R ≤ 350 m; - factors impact on the track gauge extension under difficult operating conditions; - empirical dependence of the process of the track gauge width change and the frequency of its adjustment in the cases of СКД65-Б fastener (reinforced concrete sleepers) and Д0 fastener (wooden sleepers) use in curves with radius R ≤ 350 m; - conclusions on the probability and feasibility of concrete sleepers use under mountainous terrain conditions, including difficult operating conditions (R ≤ 350 m).
The New Approach in Evaluating the Mechanism of the Blast Effect and Organizing the Blasting Operations While Tunneling
(EDP Sciences, 2020) Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Heletiuk, Ihor; Tkach, Taisiia
ENG: It is relevant for the organization of blasting operations with consideration to the mechanism of blast effect to justify new provisions due to the emergence of new explosives, means of initiating charges and instrumental measurement of parameters. In view of this, a new approach is needed for evaluating the mechanism of blast effect in the combined application of short-delay and delay-action blastings with a high level of organization and safety. Analyzing the results in the justification of the short-delayed blasting, obtained by many researchers in recent decades, its main advantages and some limitations in its evaluation have been identified. A clear justification for the combined application under seismic safety is provided. New results to explain the mechanism of the blast effect in the combined application of short-delay and delay-action blastings at tunneling facilities have been obtained. They help in the seismic action reduction under the conditions of close city development. Methodological approaches to organize blasting operations at complex facilities in Ukraine implemented during tunneling have been developed.
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 Changing the Force Factors in Temporary Lining at the Tunnel Construction by the NATM
(EDP Sciences, 2019) Kuprii, Volodymyr; Petrenko, Volodymyr D.; Kuprik, Sofiia; Kripak, Yevhenii
ENG: Abstract. The paper presents the results of a numerical analysis of force factors in temporary lining at the tunnel construction by New Austrian Tunneling Method (NATM). The relevance of the performed research is substantiated by the complexity of the temporary lining operation in the form of arches combination, anchors, and shotcrete that arose during construction of the Beskydskyi tunnel in Ukraine. NATM, used in construction, is associated with a change in the sectional area of the working and a staged installation of temporary lining, which leads to a gradual change in the stress-strain state of the "temporary lining – surrounding massif" system. In turn, this leads to a change in the force factors (bending moments and normal forces) in temporary lining. In this study, a series of finite-element models simulating the stages of rock excavation and installation of lining elements have been developed and analyzed. The obtained results allowed to determine the cardinal change of force factors in temporary lining, depending on the stage of construction. Changing the force factors at different stages of the tunnel construction by the NATM makes it possible to perform an optimal selection for temporary lining location.
Numerical Analysis of Reinforcement of Sections With Transitional Rigidity on Approaches to Railway Bridges
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, Dnipro, 2020) Marochka, Vitalii V.; Boboshko, Stepan H.
EN: Purpose. To analyze the mechanism of work of embankments, to model three-dimensional models and to compare methods of their reinforcement on transitional areas on approaches to railway bridges using the Lira software based on finite element method (FEM). To do comprehensive analysis of results and comparison of constructive performance of different reinforcement methods. Methodology. Numerical finite element modeling (FEM) had been performed to study the work of embankments in transition sections on approaches to railway bridges. Four three-dimensional models of the construction of the transitional section, corresponding to the real bridge, had been constructed. These models had been tested for nominal load to evaluate their performance relative to each other. Findings. As a result of the calculations, the deformation characteristics for the basic model and each of the reinforcement types had been obtained, and their comparisons had been made by determining the maximum vertical deformations and vertical deformations at key points. The analyze of feasibility of using the tested reinforcement methods under different real initial conditions had been performed. Originality. The main aspects of the work of the transition sections over long periods of time had been revealed. Comparisons of fundamentally different methods and types of reinforcement of sections with transient stiffness had been made. The expediency of the methods of reinforcement of the embankment construction in the transitional sections that had been proposed in previous works had been tested. Practical value. The proposed reinforcement methods may be used depending on the specific design conditions, the budget, and other factors. Evaluating the work of different types of reinforcement during numerical analysis makes it possible to move away from large-scale field trials and focus on other methods, which significantly reduces time spent on solving current problems.
Overview of Technologies For Constructing the Facilities at the Dnister Pumped Storage Power Station
(Dnipro Polytechnic (National Mining University), Dnipro, 2019) Radkevych, Anatolii V.; Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Horbatiuk, Yurii M.; Parinov, V.
ENG: Purpose. Perform an overview of the construction technologies and substantiate the effectiveness of the Ukrainian experience in building a pumped storage power station (PSPS) on the Dniester River in difficult engineering-geological conditions with the construction of large underground structures, including mine shafts and hydraulic engineering tunnels. Methods. In the work, the main technological methods have been studied and analysed of hydraulic engineering construction of complex large underground structures in the rocks with medium hardness according to M.M. Protodiakonov scale using a special method of a well lowering and a combined method of drilling and blasting operations during mine workings drivage, which is based on the slow and short-delay blasting. The anchors calculation, when driving the water sup-ply conduits, has been made from the condition of suspending the block of disturbed rock, the thickness of which was taken equal to the roof arch height according to M.M. Protodiakonov. The parameters of the sprayed plaster base concrete have also been calculated according to V.M. Mostkov theory. Findings. The analysis of the current state of research, theoretical positions and world practice of construction of PSPS has been made, which testifies the high potential of this type of energy facilities. The efficiency of the underground hydraulic engineering construction of the Dniester Station has been substantiated. The results are presented of a complex application of mining and construction methods, as well as processing equipment for the construction of horizontal and tailrace conduits, drainage adits and vertical mines for hydraulic units in difficult engineering and geological conditions. As a result of performed analytical studies, the combined method of constructing the anchor support of sprayed plaster base concrete, when driving the water supply conduits, which is the most rational for engineering and geological conditions of increased complexity, has been substantiated. Originality. The efficiency of the lowering well method in a thixotropic jacket when constructing in the soft soils has been deter-mined under the conditions of building a PSPS on the Dniester River. The step-by-step combined method of constructing the anchor support of sprayed plaster base concrete, when driving the water supply conduits has been substantiated. Practical implications. The most rational ways of conducting a range of mining-construction works have been substantiated and implemented, allowing to construct a complex pumped storage facility with a capacity of over 2.0 million kilowatts, ensuring a significant increase in the power supply capacity of the West Ukraine region.
Parameters of Typical Continuous Steel Truss Spans under a Yigh-Speed Movement
(Дніпропетровський національний університет залізничного транспорту ім. акад. В. Лазаряна, Дніпро, 2017) Reshetnov, Artem Yu.; Solomka, Valentina I.; Ovchynnykov, Pavlo A.
ENG: Purpose. Determination of the stress-strain state of a typical continuous steel truss span by calculation according to national norms and computer simulation in the conditions of passage of high-speed passenger trains. Methodology. In this work, the stress-strain state of a continuous truss span of the typical project No. 3 501.2-166 for the possibility of its application in areas with perspective high-speed railway traffic was investigated. Calculation of the specified span structure for DBN V.2.3-14-2006 «Constructions of transport. Bridges and pipes. Design rules» for railroad loading С14 was executed. The cross-sections of the elements of a continuous truss span were calculated and the necessary checks performed. For the given span structure in the software complex a model was developed and the stress-strain state at various speeds of railway transport according to European and national norms was investigated. The acceleration and deflection of a continuous steel truss span were determined and their comparison with normative requirements was performed. Findings. As a result of simulation in the software complex for a continuous steel truss span, acceleration and deflection under the action of cargo and passenger load at different speeds of movement were determined. The cross-sections of the elements of a continuous steel truss span were calculated. Originality. The results of the study can be applied in the development of national regulatory documents on high-speed rail transport and in the design of bridge structures with continuous truss spans in areas with high and higher-speed railway traffic. Practical value. The obtained results of the research will allow to effectively use continuous steel truss spans of typical designs in areas with high– and higher-speed railway traffic.
Predicting Changes of the State of a Bridge Reinforced With Concrete Superstructures in View of Operational Changes
(Uniwersytet Zielonogórski, Poland, 2019) Ovchynnykov, Pavlo A.; Dubinchyk, Olha I.; Tiutkin, Oleksii L.; Kildieiev, Vitalii R.; Sedin, Volodymyr; Bikus, Kateryna
ENG: Purpose. Bridges are the most durable and heavy duty transport facilities. Therefore, the solution of scientific and technical problems of superstructure service life predicting in the context of defect and damage accumulation that is, taking into account changes in operating conditions is on the front burner. Methodology. To solve the problem of superstructure service life predicting, the work proposes the bases and methodological developments of creep theory with increasing loads as well as regression analysis of the laboratory experiments results. Findings. The main parameters of reinforcement corrosion growth in the concrete cracks were determined under laboratory experiments. Based on the obtained results the approximate analytical dependences concerning reinforcement corrosion depth change in time at a constant value of crack width were selected. The paper substantiates validity of the analytical dependences as a result of regression analysis; proposes formulas for determining the corrosion rate of rebar in reinforced concrete superstructures. The obtained analytical dependences allowed for development of the process of predicting superstructure state changes in view of operational changes. Originality. For the first time, using laboratory experiments, the development of reinforcement corrosion in concrete cracks was determined together with assessment of time-varying corrosion depth. Practical value. Approximating analytical dependences, with a high level of confidence (95%), allow predicting reasonably the crack width in reinforced concrete superstructure. This is a significant practical value for bridge superstructure service life predicting in the context of defect and damage accumulation that is, taking into account changes in operating conditions. Formulas for determining the corrosion rate in rebar with the ability to predict the active area of corroded reinforcement have also practical value.
Prediction of the Stress-Strain State of Circular Workings in a Layered Massif by Scaling
(EDP Sciences, 2020) Alkhdour, Ahmad M.; Radkevych, Anatolii V.; Tiutkin, Oleksii L.; Bondarenko, Nataliia
ENG: The scientific and technical task for determining the stress-strain state of mine workings is complicated by the presence of a layered massif. This task assumes particular importance in the case of circular tunneling. During its operation, it is important to predict the change of the stress-strain state for the massif or to carry out the prompt determination in the change of stresses and displacements for the unsupported working. The solution of this geomechanical task allows performing geometrical matching of the working, ensuring its strength and stability in the layered massif. A numerical finite element method based on StructureCAD (SCAD) software package was used to solve it. Four geomechanical systems were calculated: "unsupported working – layered massif". Owing to the obtained results, graphs of stresses and displacements were constructed, which allow to determine these parameters for workings with different geometric parameters and χ-parameter characterizing the ratio of the elasticity modulus of the matrix and the layer. Obtained regularities of change of stresses and displacements for the unsupported working when zooming made it possible to introduce scaling-parameters, which are a dimensionless ratio of the radii for a real system and a system with a unit diameter.
Prospective Directions of the Development of Loose Medium Mechanics
(Національна академія наук Укрaїни, Київ, 2020) Bannikov, Dmytro O.; Tiutkin, Oleksii L.
ENG: At present, in the field of loose medium mechanics there is a rather serious key problem, the absence of a universal theoretical concept for considering the behavior of the loose medium under different practical conditions. Such situation significantly impedes the further development of this industry, since theoretical models of bulk material, which now have been counted about 30, practically conflict with each other. Problem Statement. In practice, such problem leads to numerous cases of failures of structures of various types, as a result of errors in determining the loads from the bulk material. Purpose. Identification and formulation of the main directions of the further development of loose medium mechanics as a separate section of soil mechanics in the composition of geotechnical mechanics. The development of these directions is a solution for overcoming the problem of creating a unified theoretical model of loose medium. Materials and Methods. The systematization and the synthesis of the accumulated information on loose medium mechanics and the development of a universal approach to describing its behavior is the main method to achieve the formulated purpose. Results. Researching in three directions is the main prerequisite for the formation of the concept of loose medium. These directions are the determination of the properties of loose materials; the determination of the pressure ratio; and the development of a model for packing grains of loose material. Conclusions. The discrete-continuum approach shall be basic concept for developing the unified theoretical model of loose medium. At the same time, all properties of loose medium are determined on the basis of its discrete nature; the equations of static equilibrium and the dynamic motion of the loose medium are formed considering it as a homogeneous continuum within a certain volume. Also, the static behavior of loose medium shall be analyzed as a partial case of its dynamic behavior rather than as an individual task with its own parameters.
Regularities of Stress State of Unsupported Working Occurring in a Layered Massif
(EDP Sciences, 2019) Tiutkin, Oleksii L.; Petrosian, Nataliia K.; Radkevych, Anatolii V.; Alkhdour, Ahmad M.
ENG: Abstract. The paper defines the regularities of stress state of unsupported working occurring in a layered massif. The relevance of the performed research is substantiated by the importance of determining the stresses of the contour of unsupported working when the elastic modulus of the matrix and the layer is varied. Since the application of analytic methods for this case is complex, we used a numerical finite element method, implemented in the SCAD. We developed a finite-element model of the above working, where the elastic moduli of the matrix and the layer varied greatly, while its position was unchanged (the layer laying in the middle of the working). The results of the numerical analysis allowed us to build the regularities of three stress components. In order to normalize cases of elastic modulus variation, a dimensionless χ-parameter is introduced which characterizes the relation between the elastic modulus of the matrix and the layer. The obtained regularities of the stress state of the χ-parameter have a functional character and allow to determine the stresses on the contour of the unsupported working, depending on the relation between the elastic moduli of the matrix and the layer for all possible spectrum of these parameters.
The Research of the Deflected Mode for the Steel Truss Bridge Span with Upper-Level Traffic by the Computer Modeling Method
(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпропетровськ, 2015) Ovchynnykov, Pavlo A.; Solomka, Valentina; Miroshnik, Vitaliy; Pinchuk, Anna
ENG: Purpose. To confirm the result of bridge span classification by using the computer modelling for truss span with upper-level traffic and polygonal lover belt and to determine minimal sufficient complexity of computational model that provides a possibility of adequate numerical calculation of given structure. Methodology. The result confirmation was executed by the comparison of stresses, that were yielded as a result of truss’ model loading with loads of predetermined class, with allowed stresses that were adopted for the determination of the afore-mentioned loading. The determination of optimal computational model was performed by the comparison of calculation results for models of different complexities. Findings. The results of the span modelling are similar enough to the results of it’s calculation, which confirms the accuracy of both methods and provides obvious idea about work of truss elements and critical places. The comparison of calculation results of different models showed that the using of shaft model with hard junctions and elements’ bending accounting is optimal. Originality. Computer modeling was used to confirm the results of span classification, which was conducted by the standard method. An optimal computational model was determined for trusses that are similar to given. Practical value. Results of analytical calculation were confirmed with demonstration of critical elements and obvious demonstration of results. The optimization of the model allows to lower calculation time and complexity of executing them for similar trusses.
Research of the Strained State in the "Subgrade – Base" System at the Variation of Deformation Parameters
(Kaunas Univ. of Technology, Lithuania, 2020) Tiutkin, Oleksii L.; Keršys, Robertas; Neduzha, Larysa O.
ENG: When building the railway lines, there are several cases of the subgrade construction, which in the future is the cause of poor operation. It lies in the fact that "diseases": defects and deformations emerge in the subgrade and the base on which it is built. These phenomena are due to the fact that, firstly, the quality of the subgrade is not consistent with the normative deformation parameters, and secondly, the soil foundation of the subgrade is weak. The purpose of this research is to obtain the strained state of the "subgrade – base" system at the variation of the deformation parameters of its elements. For this, finite-element models were developed, in which the track superstructure with assembled rails and sleepers, the subgrade and its base were reproduced. Numerical analysis was carried out in the static position on trainloads. The obtained results of the strained state of the models are components of horizontal and vertical displacements. The results of the research show that the impact of the base with lower deformation parameters is greater than in the subgrade with a reduced, unlike regulatory, the elastic modulus.
Roles and functions of asphalt sub-ballast in the modern maintenance of the European railways
(Tongji University and Tongji University Press, 2025) La Placa, A.; Autelitano, F.; Neduzha, Larysa O.; Tiutkin, Oleksii L.; Giuliani, F.
ENG: The railway network is increasingly becoming central to the socio-economic development and the decarbonisation of transport, supporting its growth in compliance with the emission reduction targets set by the 2050 European Green Deal. Thus, several programmes for the major network renewals and the construction of safe, resilient and efficient high-speed lines have been implemented. In this scenario, some construction solutions have been introduced to enhance the durability and functionality of the railway infrastructure, particularly for the ballasted track one. Among these design techniques, the asphalt or bituminous sub-ballast has emerged as a proven technology capable of improving the railway performance and durability. Derived from the road construction approach, asphalt sub-ballast has been used in the European high-speed and high-capacity lines since the 1970s, providing both structural and functional benefits. This article offers a critical review of the current knowledge on the asphalt sub-ballast applications, highlighting its technical characteristics and long-term performances. Functional, structural and economic advantages have been assessed and analysed based on laboratory scale and on-field experiences. Experimental data indeed confirm the effectiveness of asphalt sub-ballast in improving the track stability and load distribution, in providing better water drainage and in reducing fatigue induced phenomena. These enhanced properties lead to lower maintenance costs and operations, particularly those related to ballast tamping, as well as to an extended service life of the whole infrastructure. From the circular economy perspective, the re-use or recycle of wastes and by-products in these mixes amplifies the cost-benefit ratio, also improving their sustainability.
Stress-Strain State of Beam Staged Connection Point of the Railway Bridge Track-Way
(Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan, Dnipro, 2017) Kliuchnyk, Serhii
ENG: Purpose. The staged connections of the beams of railway bridge track-way have the simplest design, but some design flaws result in numerous defects. The purpose of the given work is to research the actual stress-train state of the point of connection of the stringers with the floor beams on condition of their staged interposition. It is also necessary to determine possible effect of coupled work of deck beam grid and booms on their stress-strain state. Methodology. To reach the purpose of the study the testing of the existing bridge was conducted. To measure strains (stresses) in the span elements we used the strain gages glued to flange angles of stringers and floor beams and to fillets of lower flange angles of stringers in the points of their support on floor beams. To measure deflections of the truss, stringers and floor beams from static loads we used Aistov’s and Maksimov’s deflectometers, that were installed on lower boom in the middle of span 0-1, as well as on both stringers and floor beams in the middle of the span. Deflectometers were fastened to the span and, by wire communication, to the ground surface. Findings. Stress-strain state of the point of connection of the stringers with the floor beams on condition of their staged interposition was obtained and analyzed. Analysis indicates that, apart from vertical bending of the stringers and beams, there is a significant effect of horizontal bending of floor beams and their torsion, that occur due to the coupled work of track-way beams and top booms, both for P0 beam and for other beams. Originality. Research of stress-strain state of metal track-way staged beams while considering their coupled work with bearing trusses. Practical value. While testing the span under the train load, there are significant additional stresses from horizontal bending of floor beams and their torsion in the floor beam flanges. The appearance of these stresses is caused by inclusion of stringers into coupled work with top booms. Appearing flaws in stringers are caused by local stress concentration due to design features of staged track way.
Study of the Effect of Soil Cement Elements when Stabilizing Roadbed Model in Laboratory Conditions
(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Petrenko, Volodymyr D.; Tiutkin, Oleksii L.; Sviatko, Ilona O.
ENG: Purpose. Experimental studies allow determining the stress-strain state or bearing capacity of the tested soil body. A preliminary study of the results of model testing and experimental research allows us to find the optimal solutions and to justify the parameters of the chosen technology. The purpose of this work is to determine the effect of soil cement elements when stabilizing the roadbed on a weak subgrade using the soil tests in laboratory conditions. Methodology. During the development of measures for the reconstruction and consolidation of soil bodies, their strength is tested using many methods. In all cases, we take into account the physical and mechanical characteristics of soils obtained as a result of research, as well as the existing regulatory documents. We performed the experimental studies by model testing in laboratory conditions. The model testing was based on the corresponding relationships between geometric sizes, mechanical properties of materials, loads and other factors on which the stress-strain state depends. During testing, the model was loaded gradually. We maintained each load level up to conditional stabilization of the soil deformation. We took the readings from measuring devices at each stage of loading after achievement of stabilization of soil mass deformations. We fixed the readings in the test journal. Findings. During stabilization with soil cement piles there is an improvement in mechanical properties, which leads to a decrease in deformations by 2…3.5 times. Each test is accompanied with graphs of relative deformations-stress dependence, as well as deformation curves and compression curves. According to the results of experimental studies, it can be seen that when testing a model with cement piles, compared with a model without soil cement piles, the relative deformations of the samples taken prior to the experiment and after the experiment almost coincide, indicating a decrease in deformability under load. Originality. We proved that this stabilization type positively affects the stress-strain state of the soil body, by increasing its physical and mechanical characteristics. The obtained results allow for rational design of subgrade stabilization work with the help of modern technologies. Practical value. The in-depth analysis of the results of experimental studies opens up possibilities for theoretical synthesis and development of theoretical foundations, which will allow in the future avoiding, in the similar cases, the experimental verification of the stabilization type given for the relative type of soil. It is confirmed that this method of stabilization used can be applied in real conditions.