Reducing Slab Track Vibrations by Using Asphalt Concrete in the Substructure

Vibrations of the slab track system propagated to the environment are estimated for railway tracks in which substructures are made from hot mix asphalt concrete (HMAC) and/or rubber modified asphalt concrete (RMAC). Sensitivity analysis is done to determine the ability of such layers to reduce vibrations with various frequencies, load amplitude and thicknesses of asphalt layers. Different types of substructures i.e. with or without the concrete base layer are used to assess propagated vibrations caused by the moving train. A finite element (FE) model of the ballast-less track substructure is built and the dynamic analysis is performed for various track models with asphalt layers. The FE model is in principle a two-dimensional plane-strain model with the parameters according to the common slab track systems. Ground vibrations i.e. dynamic accelerations are extracted at different recording points around the track with lateral distances 0, 10 and 20m from the loading axis. The outputs of numerical simulations for different substructure models are obtained and the possibilities of vibration reductions by various methods are discussed.