Мости та тунелі: теорія, дослідження, практика

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ENG: Bridges and tunnels: theory, research, practice

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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.
Analytical Regularities of Force Factors in the Lining of a Three-Vaulted Metro Station with Variation of the Elastic Resistance Coefficient of the Rock
(Український державний університет науки і технологій, Дніпро, 2025) Jiang, Congying; Tiutkin, Oleksii L.; Chen, Zehui; Chen, Zhixiang
ENG: Purpose. The purpose of the scientific article is to conduct a numerical analysis of pylon station models and obtain force factors for its lining. Based on the obtained factors (bending moments and normal forces), it is planned to obtain their analytical regularities for the varying elastic resistance coefficient of the rock. Methodology. The calculation scheme of the station structure should be chosen so that it corresponds to the real operating conditions of the lining to the greatest extent, reflecting the design features, lining material, geological conditions, and the construction method. The SCAD calculation software was used to calculate the pylon-type station. Findings. The foundations of mathematical modeling of a pylon station by the finite element method in a spatial setting were developed using the modified Metrodiprotrans method (based on FEM), models calculations for pylon deep metro stations were carried out by determining the parameters of equivalent bars in a spatial setting. Using the results of the regularities between the strength coefficient and the deformation characteristics of the soil (deformation modulus and Poisson's ratio), analytical regularities of force factors were determined for varying properties of the surrounding massif (elastic resistance), which for moments are power nonlinear regularities, and for normal forces are linear functions, furthermore the change in the elastic resistance coefficient with respect to the strength coefficient is a nonlinear polynomial. Originality. The originality of the conducted research lies in obtaining analytical regularities of force factors for varying properties of the surrounding massif based on the results of numerical analysis conducted on the basis of the finite element method using the modified Metrodiprotrans method. These regularities allow predicting the change in bending moments and normal forces depending on the change in geological conditions at the design stage. Practical value. The practical value of the research lies in developing the basics of the methodology for taking into account the spatial factor in the calculations of three-vaulted metro stations. This allows for more complete consideration of the complex irregular structure of pylon-type stations and obtaining force parameters in its lining that are more adequate to the real situation.
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.
Numerical and Modal Analysis of the Railway Bridge Pier
(Український державний університет науки і технологій, Дніпро, 2025) Tiutkin, Oleksii L.; Dubinchyk, Olha I.; Zhang, Quan; Du, Kaiqian
ENG: Purpose. The purpose of the scientific research is to conduct numerical and modal analyses of the railway bridge pier with a variation of load combinations and to determine the strength parameters and dynamic characteristics (shape and frequency of natural vibrations). Methodology. Pile foundations are the most economical and effective for bridge construction. In this case, the pile foundation of the overpass pier is constructed on bored piles. To reproduce the features of the pier’s pile foundation, a spatial FE-model was used, which most accurately reflects its interaction with the surrounding massif. Findings. An analysis of the results of the stress-strain state of the overpass pier foundation was performed, taking into account the train load, which made it possible to obtain a conclusion about the high bearing capacity of all parts of the “pile – pile cap” system for all considered types of combinations with a safety margin of 8 and 7 times, respectively, which indicates normal operation in the future provided an unchanged state of engineering and geological conditions and loads. The connection point of the piles and the pile cap, made of concrete class C25/30, fully withstands all types of loads presented in the combinations. A modal analysis of the foundations of the overpass pier models was performed and the frequencies and shapes of the foundation were obtained, which are equal to 4.2 Hz (main tone) … 17.4 Hz, and from comparing these frequencies with the liquefaction frequencies of wet sands (30 … 50 Hz) it is clear that the support's own vibrations cannot cause vibration liquefaction. Originality. The originality of the study lies in obtaining the values of the stresses of the overpass pier in the static formulation, as well as the dynamic characteristics (shape and frequency of natural vibrations) in the dynamic formulation. Practical value. The practical value lies in the substantiated assessment of the values of the pier’s vibration frequencies, which is based on the results of modal analysis and indicates the absence of sand liquefaction.
Solution of Task of the Mobile Loading in the Dynamic Statement
(Дніпропетровський національний універсиет залізничного транспорту імені академіка В. Лазаряна, Дніпропетровськ, 2013) Petrenko, Volodymyr I.; Petrenko, Volodymyr D.; Tiutkin, Oleksii L.
ENG: Purpose. That is the feature of static work of tunnel constructions, that their stress-strain state is formed in interaction with a surrounding rock mass. But the dynamic component of stress-strain state of such constructions is also large, as tunnel constructions are perceived, except for permanent action of surrounding rock mass, spectrum of the dynamic loadings. Analyzing every type of dynamic action, it follows also to give him appraisement from position of reflection in normative documents, as the account of most dynamic actions is only declared in them without development of some methods. Methodology. For research of influencing of the mobile loading in the dynamic statement model it is some changed in order to correctly attach loading between columns as an impulse. As well as at the conducted research of the mobile loading in the static statement, in which it was found out, that his influence on the station construction depended on the depth of contour interval, at the solution of the same task in the dynamic statement explored two models – with the depth of contour interval 5 m and 10 m. Findings. It is possible to testify from the conducted analysis, that the complex analysis of the station construction with conducting of static and dynamic calculations allows to obtain more complete information about stress-strain state, which allows to estimate the state of elements in different situations, some of which more reliable result in emergency situations and must be forecast. Originality. Influencing of the mobile loading in the static and dynamic statements has been analyzed. Practical value. The calculations of the underground stations of shallow contour interval are complemented by an important calculation in the dynamic raising, and the results of such complex analysis can be considered more complete.