Dynamic soil response to high speed rail

Abstract

Dynamic effects create many difficulties in the construction of railways in the soft soil of western Sweden. Soft soil has a low critical speed and amplifies dynamic forces. Sweden’s planned expansion of the rail network and the desire to increase the speed of trains are in need of an easy and efficient method to estimate dynamic responses. This study uses the ROSE and STEM numerical models to obtain the dynamic displacements under these conditions. Both models are open-source, and fully model the train-track interaction to provide an accurate distribution of the forces. Analyses are performed for natural transition zones and at higher velocities that amplify dynamic effects. The results indicate that the dynamic amplification is much higher for a sudden transition than for more gradual cases and that higher speeds increase dynamic displacement. Soil improvements are also analyzed and resulted in a very small area ratio for the lime cement columns to meet the requirements. To implement these complex conditions, the uncoupled method used in ROSE is too simplified. The determination of soil spring stiffness used for ROSE is inadequate when there are multiple soil layers. For future use of the models, a different method is recommended. However, STEM is capable of modeling more complex models and dynamic effects.