Modelling the suction-dependent plastic shakedown limit of unsaturated fine/coarse soil mixture with consideration of soil-water retention curve

An interlayer soil was identified in the French conventional rail tracks, corresponding to a mixture of subgrade fine and ballast grains. Experimental results show that permanent strain such fine/coarse can be at stable or unstable state, depending on stress level with respect plastic shakedown limit σ dth (the maximum for strain). As water content changed, matric suction ψ changed subsequently, leading change . In this study, model incorporating soil–water retention curve proposed describe variation varying coarse grain f v This implied under saturated state dth-sat , reference dth-ref ref parameters related curve. The validated using three series studies literature. Based an existing approach implying representative rate 1/ s values determined these series. For each series, obtained divided into two groups: first group used determine parameter B relationship between while second adopted validate previous A reasonably good agreement measurements calculations studies. comparison made, showing performance describing variations