Dynamic characterisation of railway track superstructure for the analysis of ground borne vibration in soft subsoil

¹ Department of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands
² Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The railway track superstructure including rails, sleepers and ballast is the primary interface between the train induced dynamic loads and the underlying embankment and subsoil, and plays a crucial role in load transfer, energy dissipation, and vibration attenuation. Accurate assessment of the train induced dynamic response of soft soils requires prior characterisation of the load transferred by the track superstructure. Hammer impact testing is an effective method for evaluating track dynamics, as it excites a broad frequency range and enables identification of the system natural frequencies through resonance amplification in the measured response. This study analyses the dynamic response of a laboratory railway track model consisting of rails, sleepers, and ballast subjected to hammer impact excitation as an aid to the development of a reliable finite element (FE) model of railways on soft soils. A three-dimensional finite element model of the experimental setup is developed in LS-DYNA to simulate the transient dynamic response of the track system. The numerical results are compared with the vibration time history and the frequency response function measured experimentally on the ballast layer. The finite element model is used to perform a sensitivity analysis to evaluate the influence of relevant input parameters of the track on the dynamic response measured on the ballast layer. The results suggest that different track components govern distinct frequency ranges of the system response, enabling efficient modelling strategies for railway systems on soft soils.