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Title: Railway trackbed deterioration
Author: Yu, Ji
ISNI:       0000 0004 5990 9171
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2016
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In this thesis, the main objective is to identify the resilient deformation behaviour of rail trackbed especially in ballast and calculate the stress distribution. A purpose-designed three dimensional Finite Element railway trackbed model is presented in which linear elastic behaviour is assumed in all parts of the model. The study has also evaluated the effects of different variables including moving load magnitude, loading speed and stiffness of materials on stress conditions and deflections based. A comprehensive literature review on a wide background of railway trackbed has been carried out. Railway ballast specifications, deformation mechanisms, resilient and permanent deformation behaviour of granular material, introduction of fouling material and its influence on ballast behaviour are explained to provide the basis for trackbed analysis. Results show that a higher vertical displacement underneath the sleeper may occur when the loading speed is higher than 120km/h. Also, higher speed and Young’s modulus of ballast can result in higher damaging stresses. A stiffer subgrade can result in less rotation of sleeper. A significant effect of subgrade stiffness on stress paths and rotation of sleeper can only be found when Young’s modulus of subgrade is in a low level. Stiffer rail pad can lead ballast element get cracked more easily. Softer pad results in less damaging stresses. In addition, there is no obvious change of either the stress ratio or sleeper rotation as stiffness of the ballast increased.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TF Railroad engineering and operation