Influence of asymmetrical topology on service performance of railway prestressed concrete sleepers

Railway networks are the catalyst for economic and societal growth of the cities, region and country. Their physical assets consist of infrastructure, rolling stock, signaling systems and electrification. By nature, the railway infrastructure is nonlinear, judging from its behaviors, geometry and alignment, wheel-rail contact condition and operational parameters such as tractive efforts. It is noted that degradation of ballast over time has not been considered in most train-track interaction models. Indeed, the ballast degradation can cause differential settlement along the track and induce dynamic impact forces acting on partial and unsupported tracks. In addition, it is reportedly that ballast damages underneath a local railseat can cause the risk of centre-bound cracks in concrete sleepers due to the unbalanced support under sleepers. These cracks are initially vertical under bending mode and can be further developed, resulting in unsecured spreading rail gauge. This paper presents nonlinear finite element simulations of concrete sleepers in a track system. The simulations take into account the tensionless nature of ballast support coupled with the asymmetric topology. The finite element model was calibrated using static and dynamic responses in the past. In this paper, the influences of topologic asymmetry on both static and dynamic behaviors of sleepers are firstly highlighted. The topology asymmetry is often caused by on-site modification for structural retrofit or local track timber-plating component arrangements. In addition, it is the first to demonstrate the effects of sleeper length on the service performance of concrete sleepers at risk. The insight into the influences of asymmetric topology will help improve the rail construction criteria in order to adjust support profile and appropriately mitigate sleeper/ballast interaction