CMEES-INF-119: Fibre reinforcement for railway ballast

Railway transportation of both freight and people is key to significantly reduce CO2 emissions. There are several reported advantages of railway transportation, however, there are also some challenges that need tackling. To compete with other modes of transportation, rail authorities are under pressure to minimise track maintenance cost, and to find alternative materials and approaches to improve the performance of rail tracks. Modern rail tracks are formed by super-structure (rails, fastening systems and sleepers) and sub-structure (ballast, sub-ballast and sub-grade). Recent studies have focused on using polymeric fibres (narrow strips) for reinforcing railway ballast. Full scale laboratory tests have shown that ballast reinforced with randomly distributed fibres exhibits reduced plastic settlement and greater resistance to irrecoverable settlement than unreinforced solutions (Ajayi 2014). The results available also indicate that using fibre reinforced ballast can provide more uniform stiffness and stress distributions across the length of the sleepers. However, there is limited understanding of what the optimum properties of those reinforcement elements are, so that they meet the design requirements for reinforced ballast over the whole design life of railway track.

The proposed project will focus on the properties of the fibres currently considered for reinforcing railway ballast, particularly on their mechanical response (isolated and in contact with ballast). The short- and long-term tensile behaviour of the fibres will be analysed, as well as the fibre-ballast interaction. The effects of long-term dynamic loading on the fibre properties will also be investigated. Coefficients of interaction between the fibres and ballast will be derived for different failure mechanisms. By understanding the role of fibre material, the project will contribute to the development of guidelines for optimal design of fibre reinforced ballast.

If you wish to discuss any details of the project informally, please contact Margarida Pinho Lopes, Infrastructure research group, Email: [Email Address Removed], Tel: +44 (0) 2380 59 8363.

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