Ballast track is the most widely used track for the railway transport, and ballast bed plays a significant role to provide resistances during train operation. Generally, the ballast bed consists of crushed stones. To achieve the mitigation of ballast degradation, the first priority is to describe the degradation development and to study its effect factors. The influence of ballast morphology (particle size and shape) on ballast degradation is examined here using the Los Angeles Abrasion (LAA 1) test in combination with 3-D image analysis. LAA tests are used to obtain the deteriorated ballast. Then, based on the 3-D images, the changes of ballast particles after the tests were analysed. To quantify the ballast degradation (abrasion and breakage), the Abrasion Depth based on the analysis of 3-D images were proposed, while ballast breakage was estimated using the broken particles ratio. The results have shown that ballast degradation is directly related to the ballast morphology. The proposed image-based procedure can effectively be applied to assess ballast degradation. The results can be used for ballast material standardization, modelling of ballast degradation process and maintenance cycle prediction.

Image analysis for morphology, rheology and degradation study of railway ballast A review

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During the development for railway, ballasted track is dominant structure and makes up more than 95% of the whole track modes. However, its shortage is considerable in high speed railway and heavy haul system. Regarding to the ballasted railway track's defects as particle breakage, settlement, and geometry irregularity which lead to enormous maintenance and cost, Polyurethane reinforced ballasted track has shown great application prospect. This reinforcement method can settle several problems, including stiffness adjustment, ballast flight prevention, and stability in specific zones, such as curve, tunnel line. This paper presents a comprehensive review of polyurethane research and application within ballasted track system. Besides, according to different usage, varies of bonding methods are also introduced in this paper. However, some challenges still exist such as maintenance and cost, potential solutions are put forward for further investigated and validated, consequently. Accordingly, an overall prospect of polyurethane reinforcement in railway system is presented.