Wyniki wyszukiwania - BazTech

1

Experimental and theoretical evaluation of side tamping method for ballasted railway track maintenance

Przybylowicz Michal, Sysyn Mykola, Kovalchuk Vitalii, Nabochenko Olga, Parneta Bogdan

Transport Problems

|

2020

|

T. 15, z. 3

93--106

EN

Ballast layer is the most weak element of railway track that causes track geometry deterioration. At the same time, it is subjected to intensive particle breakage during the corrective tamping. This causes high maintenance costs of ballasted track. The present paper is devoted to the study of tamping methods. The present machine tamping methods are considered and compared. The possible influence of the tamping technology on the ballast-related maintenance costs is analyzed. The side tamping technology is studied in detail with theoretical and experimental methods. The process of material transport during the side tamping is studied using a scale model of ballast layer and photogrammetric measurements. A theoretical finite element model (FEM) is validated to the experimental results. The study shows that the side tamping is a promising method for the development of a universal, superstructure independent tamping technology.

2

Study of the temperature field and the thermo-elastic state of the multilayer soil-steel structure

Kovalchuk Vitalii, Hnativ Yuriy, Luchko Joseph, Sysyn Mykola

Roads and Bridges - Drogi i Mosty

|

2020

|

Vol. 19, no. 1

65--78

EN

The technology of renewal of metal corrugated structures allows efficient and economical reconstruction of existing reinforced concrete structures by the method of encapsulation. However, such structures can be exposed to adverse temperature effects that in combination with traffic loadings could influence the operational reliability of the structures. This article deals with the method of evaluation of the stress-strain state of a three-layer cylindrical structure. The technique is based on the thermo-elasticity theory. The study is performed in two steps: determining the temperature field of a structure, and then calculating the temperature stresses and deformations. As a result of calculations, it was established that the level of temperature field and stresses in a three-layer structure caused by the maximum and minimum ambient temperatures can reach a significant level.

PL

Technologia wzmacniania istniejących żelbetowych obiektów inżynierskich elementami z blachy falistej umożliwia ich sprawną i ekonomiczną naprawę. Niemniej jednak, takie konstrukcje mogą być narażone na niekorzystne oddziaływanie temperatury, co w połączeniu z obciążeniem ruchem może wpływać na ich niezawodność. W artykule przedstawiono metodę wyznaczenia stanu naprężeń i odkształceń w trzywarstwowej konstrukcji o przekroju kołowym. Przedstawiona metodologia jest oparta na teorii termosprężystości. Praca została podzielona na dwa etapy: określenie pola temperatury w obrębie konstrukcji, a następnie obliczenie naprężeń termicznych i odkształceń. W wyniku obliczeń ustalono, że wartości pola temperatury oraz naprężeń wywołane w konstrukcji przez wpływ maksymalnych i minimialnych temperatur otoczenia mogą okazać się istotne.

3

Stiffness and strength of structural layers from cohesionless material

Gerber Ulf, Sysyn Mykola, Zarour Jandab, Nabochenko Olga

Archives of Transport

|

2019

|

Vol. 49, iss. 1

59--68

EN

The deformation modulus and permissible stress are two independent parameters that depict the carrying capacity of foundations, including earthworks and ballast layer. Nevertheless, while designing the track superstructure or controlling its state, they are considered separate to each other, even though they are terms of the same measure. The scientific problem is due to the practical necessity of unified building rules and standards. The carrying capacity of earthworks and foundations is regulated with standards based both on deformation and on stress criteria, which are not related to each other. This plays particularly important role for railway ballast layer, as an intermediate between the solids and soil. The objective of the present research is to estimate the relationship between deformation modulus and the strength of ballast layer. An overview of modern approaches according to the relation between the stiffness, deformation modulus, elasticity and strength of soils and crushed stone is done. The strength of ballast layer is considered depending on the experimental test: the direct shear test, compressive strength in the uniaxial or biaxial stress state. Load transfer model in crushed stone is proposed. The load transfer angle and cone of loading distribution are determined based on the load transfer and compressive strength models. The relation between deformation modulus and strength is derived from two simple laboratory experiments with cohesionless ballast material. The experiment tests have shown that the ballast stiffness as well as its strength are influenced with the support stress. The measurement of elastic and residual settlements for the different support stress values enables to determine the relation. It can be potentially used for the development of methods for the ballast compaction control, unification of construction norms. The research result should be considered as an approach for unification of two different ways to reflect the carrying capacity of ballast layer.