Кафедра "Рухомий склад та колії"

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ENG: Department of Rolling Stock and Track

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Determining Patterns in the Stressed-Deformed State of the Railroad Track Subgrade Reinforced with Tubular Drains
(РС ТЕСHNOLOGY СЕNTЕR, Kharkiv, Ukraine, 2020) Luchko, Josyp; Kovalchuk, Vitalii V.; Kravets, Ivan B.; Gajda, Oleksiy; Onyshchenko, Artur
EN: The technical condition of the railroad track subgrade has been analyzed, as well as the issues related to ensuring its strength and stability when exposed to floodwaters and when the track's sections are overmoistened during operation. As a result, it has been established that it is necessary to develop methods aimed at improving the subgrade's carrying capacity. The georadar research has explored the problematic areas of the railroad track subgrade, based on which the distribution of subgrade heterogeneity in the vertical plane, as well as the boundaries of its location, were established. Therefore, georadar research makes it possible to detect hidden defective sites in the subgrade without disrupting its strength characteristics. A technique has been proposed to improve the carrying capacity of the failed subgrade of a railroad track using the combined arrangement of drainage pipes in the vertical and horizontal directions in the railroad embankment. The special feature of this technique is the possibility to drain water at the different levels of surface water, which provides for an increase in the carrying capacity of the failed subgrade. The strained-deformed state of the subgrade reinforced with tubular drainage has been investigated. The result has proven the effectiveness of the use of tubular drainages to improve the carrying capacity of the railroad track overmoistened subgrade exposed to constant and temporary loads. This study findings have established that the deformity of the subgrade increases when using tubular drainage, though this occurs only in the initial period of its arrangement, in further operation, when it removes water from the subgrade body, the carrying capacity of the subgrade, on the contrary, will improve due to the enhanced physical and mechanical properties of soils.
The Study of Strength of Corrugated Metal Structures of Railroad Tracks
(НПП ЧП «Технологический Центр», Харків, 2017) Kovalchuk, Vitalii V.; Marcul, Ruslan V.; Bal, Olena M.; Milyanych, Andriy R.; Pentsak, Andrii Ya.; Parneta, Bohdan Z.; Gajda, Oleksiy
EN: The analysis of the main defects of metal corrugated culverts of the railway, which arise as a result of operation, was conducted, and the problems of providing their durability and strength were highlighted. The problems of adaptation of foreign regulations for designing metal corrugated structures at Ukrainian railways and motor roads were analyzed, the results of experimental and theoretical calculations of bearing capacity of metal corrugated structures were presented. The MCS strength at boundary loading with the railway rolling stock was analyzed by the indicator of influence of corrugation (corrugation dimensions) and the characteristics of soils on their stressed-strained state. Calculation of equivalent forces was performed by the procedure of calculation of railway strength and stability using the finite-element method. The numerical calculation of the stressed-strained state of the MCS was obtained using the licensed software FEMAP with MSC NASTRAN. An analysis of multi-choice calculations of the strength of MCS, made of corrugated structure Multiplate MR150 with thickness of a corrugated sheet of 6 mm, with dimensions of corrugation waves of 150×50 mm, showed that its bearing capacity is provided at degrees of compaction of soil backfill from 0.9 to 1.0. Based on the obtained data, it was found that the direct cause of occurrence of residual deformation of metal corrugated pipe may be an increase in stresses in metal sheets of the pipe up to the values that exceed permissible stresses and as a result of local initiation of a plastic hinge. The condition of initiation of a plastic hinge, which takes place in the MCS arch, holds only if there is adverse simultaneous influence of two factors (causes): letting inequalities develop beyond permissible values without taking measures for its elimination and a decrease in the degree of compaction of backfill soil below 90 % (the second cause). In the absence of one of the causes, a plastic hinge might not emerge. In the joint effect of both causes, the first cause, the impact share of which is 42 %, prevails, whereas the share of the second cause is 22 %. The obtained results of the MCS bearing capacity are needed for optimal MCS designing, establishing causes of defect emergence, timely making relevant engineering decisions in order to increase the MCS bearing capacity and reasonable use of funds for the construction or reconstruction of existing transport facilities with the use of metal corrugated pipes. The results of the study may be used by engineers of Bridge testing stations of Ukrrailway and Ukravtodor and by designing organisations involved in designing metal corrugated structures of large diameters.