Optimization of FFU synthetic sleeper shape in terms of ballast lateral resistance

Abstract

Fiber-reinforced foamed urethane (FFU) synthetic sleeper is used in ballasted track with the potential problem of insufficient lateral resistance due to lower weight and smooth surface compared with concrete sleepers. In this paper, the lateral resistance of prototype and modified FFU synthetic sleepers was investigated by single tie push tests and DEM analysis, where the real shape of ballast particles was created using 3D scanning technique. Results indicate that due to the smooth surface of sleeper facets, the lateral resistance of prototype FFU sleepers is reduced by 10-15% and governed by the interactions of shoulder ballast and sleeper ends. On the other hand, modification of the sleeper shape by adding FFU strip block along sleeper base and sides increased lateral resistance up to 19 % of prototype sleepers with higher interlocking ability between ballast and sleeper sides. Results could be used to develop modified FFU sleepers for application in various ballasted tracks.