Dietmar Adam

Dynamic Aspects of Rail Tracks for High-Speed Railways

The dynamic behaviour of a railway system depends on the interaction of its three subsystems: the vehicles, the rail track and the subsoil. The motion of trains induces various dynamic effects on tracks. Vehicles moving with high speed generate waves, which propagate both to the track and the ground influencing the traction of the train significantly. In order to minimise the mentioned effects, specific designs for rail track systems are required. In this paper, an overview of significant dynamic aspects and rail track models is given. Furthermore, a design model is presented, which allows the determination of the dynamic response in different rail track systems due to a load moving with constant speed. The pavement and the rail are considered as an infinite flexible beam resting on continuous spring–dashpot elements simulating ideal high-speed rail tracks. The solution is found by transfer functions consisting of series approximation. Furthermore, a model is proposed that comprises an additional bedding of continuous springs between the flexible beam and the spring–dashpot elements. Properties of spring–dashpot elements simulating the bedding of the layered subgrade structure are calculated from a dynamic cone model. The results of large-scale in situ tests involving speeds up to 230 km/h carried out on high-speed rail tracks are presented. Finally, practical recommendations for the design and construction of the railway track are formed on the basis of the mentioned theoretical investigations, parametric studies, in situ measurements and field observations.