Numerical and physical models for predicting responses of ballasted tracks with voided ballast layer effect on sand embankments

ABSTRACT Track ballast movement is a crucial factor for differential track displacement. If the differential displacement is large, the derailment of the train is apparent. Research on the stiffness reflecting the subgrade and unbounded materials is still limited with the displacement of voided ballast layers on the railway embankment. In this study, we created and numerically validated a 1-g model (1:4 scale) of a track ballast system on sand embankments under repeated loadings. According to the numerical results, the variation of embankment heights and train speeds provides a few different maximum and permanent displacements. Also, the ratio of the settlement of voided ballast layer and that of subgrade layer is an essential key providing the high permanent displacement of the track, whereas the ratio of Es/Eb is either high or low value.