Comportement d’un support d’appareil de voie soumis à l’exposition gel-dégel
Files
Dubucq_54261300_Iserentant_38921300_2018.pdf
Closed access - Adobe PDF
- 20.73 MB
Details
- Supervisors
- Faculty
- Degree label
- Abstract
- Railway sleepers ensure the right position of the railway tracks along the railway switches as well as their stability. Formerly made of wood, they are nowadays replaced by prestressed concrete railway sleepers, more sustainable and especially eco-friendlier. Prior to being used, railway sleepers must pass laboratory tests. The freeze-thaw test, for instance is mandatory to obtain the commissioning accreditation. During this freeze-thaw experiment on the sleepers, a crack may appear in the middle row of prestressed wires, resulting in an invalid test. It is therefore necessary to draw attention to the forces that tend to split the object to avoid this problem in the future as well as to match Infrabel’s expectations. Sleepers may be of different lengths, depending on their position and of the different sections. This paper focuses on three geometries owing to the fact that those sleepers are concerned by the same issue. First, the forces affecting the prestressed beam have been highlighted. There are, on the one hand, the mechanical effects from the prestressing and on the other, the thermal effects due to changes of temperature in addition to the damage caused by frost inside the concrete. During the test, no other solicitation is applied. Second, an experimental study aimed to validate the ABAQUS finite elements models and to find some unknown parameters has been carried out. This paper has analysed each effect individually before studying their shared action. Finally, the contribution of each phenomenon on the crack has been quantified. The study has demonstrated that prestressing involves excessive stress in the element which causes damage to the concrete. The effect of frost aggravates the deterioration and eventually a crack appears. Therefore, it’s necessary to reduce the stress in the wire and also to implement a strategy that would improve the tensile strength of the products. Reassessing the prestressing system may also be an effective solution. Finally, this paper has provided an opportunity to demonstrate the relevance of the freeze-thaw test which goal is to reproduce the most extreme Belgian weather conditions.