Influence of unsupported sleepers on the dynamic response of a heavy haul railway embankment
- Authors: Shi, Jin , Chan, Andrew , Burrow, Michael
- Date: 2013
- Type: Text , Journal article
- Relation: Proceedings of the Institution of Mechanical Engineers Part F-Journal of Rail and Rapid Transit Vol. 227, no. 6 (November 2013 2013), p. 657-667
- Full Text: false
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- Description: It is not uncommon for conventional ballasted railway track systems to have unsupported sleepers due the uneven settlement of the ballast or subgrade. In order to investigate the possible implications of unsupported sleepers, this paper describes the development of a dynamic finite element model which includes wheel/rail friction. The developed model was used to investigate the behavior of a section of existing track on the ballasted Shuohuang heavy haul railway line in China. The investigation showed that the maximum displacement of the rails and sleepers increases significantly with the number of consecutive unsupported sleepers. Furthermore, the magnitude of the displacement between an unsupported sleeper and the ballast is likely to greatly exacerbate ballast/sleeper attrition and reduce the fatigue life of the hanging sleeper. An increase in the number of unsupported sleepers amplifies these effects. In addition, it was found that the sleepers adjacent to unsupported ones carry an additional load resulting potentially in their increased wear and additional damage to the substructure. To better understand the wider implications of the presence of unsupported sleepers on track performance, the stability, safety (in terms of derailment) and potential for rail and substructure damage were computed as a function of the number of unsupported sleepers (one to four) and compared with specifications. The results showed that the number of unsupported sleepers has a significant adverse impact on all four measures. However, while the effects on stability, safety and rail damage were within the limits suggested in specifications, even when four sleepers were modeled, the potential for substructure failure within a typical design life of the railway system was identified.
- Description: C1
Measurements and simulation of the dynamic responses of a bridge-embankment transition zone below a heavy haul railway line
- Authors: Shi, Jin , Burrow, Michael , Chan, Andrew , Ying, Jie Wang
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Rail and Rapid Transit Vol. 227, no. (2012), p. 245-268
- Full Text: false
- Reviewed:
- Description: Chinese Railways is seeking to increase the capacity of many of its heavy haul railway lines by increasing their utilization and at the same time increasing axle loads from 250 to 300 kN. These projected increases in railway traffic may result in accelerated deterioration of the railway network. A vulnerable part of the network, are bridge–embankment transition zones which frequently experience high degradation rates. To investigate the possible implications of the forecasted increases in railway traffic on these structure, a study was carried out which consisted of instrumenting a transition zone to measure accelerations under existing loads and building a three-dimensional finite element dynamic model of the bridge–embankment transition to predict the effects of the anticipated future traffic. The results of the study indicated that commonly used measures of stability, safety and substructure damage would remain within specified limits, despite the projected increases in axle load. However, excessive wear of the wheel and or rail may occur.