Settlement control of simulated ballast layer with geogrid reinforcement

Abdul Rahman, Norsharina (2015) Settlement control of simulated ballast layer with geogrid reinforcement. Masters thesis, Universiti Tun Hussein Onn Malaysia.

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Abstract

Railway track is an important part of the transportation infrastructure of a country and playing a significant role in sustaining a healthy economic. It provides a quick and safe public and freight transportation system. Rail track needs to be maintained to make sure it is in a good condition in order to provide an optimum performance. Unfortunately, in railway system most attention has been given to the track superstructure that serves the railway, and less attention has been given to substructure that supports the foundation of the track. The most important requirement in railway system is that, the track geometry must be maintained during operation. Poor track geometry can lead to settlement of the track that caused by the degradation of the ballast i.e. ballast breakage. Many researchers have done investigations to understand how the track structure components work and the inclusion of geogrid in ballast layer to reduce the settlement. The present study recreates the composite foundation in a lab-scale static test with geogrid placed at various heights in the ballast layer. The steel model box measured 180 mm x 180 mm x 180 mm. There was no apparent yielding of the ballast layer, with or without geogrid inclusion, indicative of a strain-hardening behaviour of the material under load. The inclusion of the geogrid in the simulated ballast layer show a significant effect on the resulting reduced settlement. This can be shown for sample Dg = 50 mm that had experience less settlement than the other. A graphical analytical method was next adopted to identify the Ballast Breakage Index (Bg) in relation to the overall settlement reduction. Overall particle breakage was not found to be expediently mitigated by geogrid installation in the ballast layer. The settlement reduction though was very much attributed to lateral spread control by the geogrid reinforcement. The geogrid deformation shows a significant with the stress that been applied to the sample. Surface tear is the highest deformation for the geogrid. This is because when the stress applied, ballast in the sample being pushed through the aperture instead of interlocking with the geogrid.

Item Type:Thesis (Masters)
Subjects:T Technology > TF Railroad engineering and operation
ID Code:7986
Deposited By:Normajihan Abd. Rahman
Deposited On:28 Apr 2016 12:35
Last Modified:28 Apr 2016 12:35

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