Parametric study of resilient response of tracks with a sub-ballast layer

Abstract

Formulation of a rational design methodology for laying or upgrading tracks for heavier and faster trains requires investigation of the effect of various track parameters on overall track responses. For this purpose, a three-dimensional linear elastic finite element model, 3D20N, is developed that uses 20-noded brick elements and 16-noded surface elements and models rails as one-dimensional beam elements. Modelling details related to rail elements enable this model to predict the track responses accurately. Assessment of predictive capabilities of the model has been carried out by detailed comparisons with other numerical models and measured field test results. A detailed parametric study of the track responses was carried out using this model for a typical track with a sub-ballast layer and by adopting a practical range of track variables. Subgrade modulus was found to be the most influential track parameter on the overall track responses. The next most important track parameters were depth of sub-ballast, rail moment of inertia, and tie spacing. Practical implications of predicted parametric trends are discussed.