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The Effect of Traffic on Ballast Settlement

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dc.contributor.advisor Mequannent, Mulugeta (Mr.)
dc.contributor.author Sisay, Atumo
dc.date.accessioned 2021-10-19T06:07:08Z
dc.date.available 2021-10-19T06:07:08Z
dc.date.issued 2019-09
dc.identifier.uri http://etd.aau.edu.et/handle/123456789/28219
dc.description.abstract Many of the world’s railways run on ballasted track, which has for nearly 200 years provided a stable support for train operation. However, with trafficking the geometry of the track deteriorates, mainly as a result of the development of differential settlement of the track-bed. The main factor that contribute for the deterioration of track components is traffic load. Explanations on how the speed, load and repetition of traffic influence the long-term settlement of ballast in ballasted track is very scarce. Having in mind that tracks subjected to the same load show different settlement behavior, explanations of track settlements in accordance with the speed, load and repetition is needed. This study is motivated to show how traffic affects the long-term settlement of ballast and how the traffic parameters (speed, load and repetition) contributes in the process. Using finite element modeling software, three-dimensional track is modeled and analyzed for different values of speed, load and no of repetitions. Drucker Prager plastic model is applied for the ballast and sub-ballast materials of the track. To get the parameters for the Drucker Prager plastic model of granular materials, triaxial test simulation is performed using discrete element software. Hertz contact theory is used to model the contact between the wheel and rail. The long-term settlement behavior of ballast material is analyzed by applying 10,000 cycle of moving axel load. According to the analyses a change in the speed and the number of repetitions of train movement changes the permanent settlement of ballast more than the variation in load. Increase in the speed of train movement by 20km/hr will increase the stress transferred to the subgrade by up to about 1000kpa. Speed of train movement is most contributing parameter in the degradation of ballast material more than the load and no of repetition. In a conventional ballasted track after about 6,000 repetition of train movement ballast material will start to decrease its performance. So, careful monitoring and periodic maintenance will be necessary. en_US
dc.language.iso en_US en_US
dc.publisher Addis Ababa University en_US
dc.subject Ballast en_US
dc.subject Speed en_US
dc.subject Axel load en_US
dc.subject Number of repetitions en_US
dc.subject Settlement en_US
dc.subject Modeling en_US
dc.title The Effect of Traffic on Ballast Settlement en_US
dc.type Thesis en_US

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