Three-dimensional modelling of high speed ballasted railway tracks

In the present paper, a three-dimensional dynamic railway finite-element model, is utilised to study the geotechnical performance of high speed railway tracks. This model takes into account many of the railway track components such as multi-layered ballast and subgrade, nonlinearity in resilient behaviour of the sub-soil, and track-train interaction. Different features of the developed model are briefly presented. The effects of train speed, ballast and subgrade stiffness, and nonlinearity of the soil behaviour are then investigated. The results of the numerical simulations regarding the track response and required maintenance levels, in terms of the stress and vibration level experienced by the ballast and subgrade are also discussed and compared to site measurements. Track design methods are also reviewed, and a design method based on the dynamic finite-element analysis is proposed and discussed, which aims at minimising railway track maintenance levels by protecting the subgrade from dynamic ground amplification for speeds approaching the Rayleigh wave velocity, and also aims at minimising ballast maintenance by setting a maximum ballast particle velocity.