Soil Mechanics of High Speed Rail Tracks

As high speed rail is becoming increasingly popular around the globe, alignments are being forced onto marginal land due to land costs and the requirement for straight tracks. Rail foundations spread the applied wheel loads to prevent damage to the underlying in-situ soil upon which tracks are built. Designs which cannot sustain the resulting stresses will cause serviceability issues and will require overhaul, disrupting services and costing heavily. The project investigates such problems and is computational in nature, employing Imperial College’s Finite Element Program (ICFEP) for a parametric study. Increasing ballast layer thickness has been shown to decrease both deflection under load and cause less strain in the subgrade, thus improving performance and design life. It has also been shown crushed rock ballast may be replaced by cheap, sustainable sandy sub-ballast. The study shows despite the additive effect of many wheel impulses, track movements are smaller at higher speeds.