Assessment of design parameters of a slab track railway system from a dynamic viewpoint

The development of the ballastless slab track, with applications especially on soft soil in combination with loading by high-speed trains, puts several specific engineering demands. One of these is how to provide the required vertical stiffness of the track system. According to the most common approach massive soil improvements are applied. An alternative to this would be to increase the bending stiffness of the slab, e.g. by applying an eccentric reinforcement. Both solutions have consequences for the dynamic track and ground response. In this contribution, the classical model of a beam on elastic half-space subject to a moving load is employed to assess effectiveness of these engineering solutions by analysis of their influence on the generalized dynamic track stiffness. The aim is to minimize the level of slab vibrations, in order to prevent deterioration. The effect of variation of other track properties is also evaluated. It is shown that for high frequencies an increase of the track stiffness is most effective, whereas for low frequencies soil improvement is a better solution. It is further shown that a relatively high track mass generally decreases track vibrations in the relevant frequency domain and that the width of the slab is an important parameter to control the level of track vibrations.