Influence of non-linear soil properties on railway critical speed

The design of high-speed railway lines involves geotechnical challenges, one which is the risk dynamic track amplification, for example on sections where train speed approaches track-ground critical speed. In these cases, soil strains increase significantly with an in speed, far exceeding limits linear elastic behaviour. This can result a non-linear reduction stiffness. To better understand this relationship, paper studies influence non-linearity concrete slab and ballasted tracks. perform in-depth analysis into two models are used: 3D FEM approach, novel dispersion curve technique. Using models, effect plasticity studied, different ranges found to play important role. Secondly, thickness loading magnitude evaluated. It shown that tracks deeply affected by behaviour, compared track. Further, it tracks, relationship between shallow upper layer be weak.