Analysis of nonlinear soil modelling in the subgrade and rail track responses under HST

• We incorporate the non-linear soil behaviour (ext. Masing rules) in rail track modelling (3D FEM) under high speed trains.
• The non-linear soil modelling is fundamental to accurately predict the subgrade and track responses.
• Linear model fairly predicts accurate stresses and strains in most of the subgrade.
• Linear model underestimates the peak rail displacement.

The paper focuses on the numerical consideration of the subgrade shear strain dependence of stiffness and damping in the simulation of a rail track under a High Speed Train (HST). The numerical simulations are done using the quasi-static axle load of a Thalys HST on a 3D Finite Element (FE) model representing track and subgrade. A nonlinear model that follows the hysteretic curve is described and used to simulate nonlinear behaviour of the geomaterials in the subgrade. The relevance of simulating these materials using nonlinear models is studied through comparison with results obtained using a linear model. The results show that very high stiffness variations occur in the soil immediately below the track and that a nonlinear approach is needed to obtain correct stress/strain state in the subgrade and to accurately predict the peak displacements in the rail.