Modélisation du comportement d'un remblai renforcé sous chargement ferroviaire de type TGV : Thèse présentée pour obtenir le grade de Docteur de l'Université Paris-Est, discipline Géotechnique

摘要

This study focuses on the numerical modeling of the Mechanically Stabilized Earth (MSE)walls behavior under High Speed Train (HST) loading.First, the state of the art in reinforced earth as well as in railway dynamics modelingis analyzed. Then we present results coming from the testing of a one-scale reinforcedembankment submitted to harmonic loading. They indicate that tensile forces in reinforcements,stresses and displacements depend on loading frequency which is related to trainspeed. One proposes a 3D Finite Element Model (FEM) in order to numerically reproducethis experimentation. The numerical results fit reasonably well with the experimental ones,highlighting the great importance of the choice of the constitutive law for the soil, reinforcementand facing.The same model is used to locally investigate the soil/reinforcement interface behaviourduring a harmonic loading in steady-state. The confining pressure presents significantvariations along the reinforcement strip during the dynamic loading while tensile forcesare less affected by the load. Nevertheless, the global interface stability remainsacceptable compared to a static load.A second numerical model is proposed, which represents a bigger embankment.The multiphase model is used to represent the reinforced soil and moving coordinates areused to take into account the moving train. Theoretical developments of this model and itsimplementation into CESAR-LCPC FEM code are detailed. The results indicate that thetrain speed does not play a big role in the overall response of the structure, in the case of astiff reinforcement comparable to the experimental one. If the embankment is weaker, theHST speed may be close to shear waves speed within the soil, which has significant consequencesinto the structure, particularly on the stability of the soil/reinforcement interface.Globally the experimental results and those coming from both numerical modelspresent the same trends: the dynamic effect coming from the train passing leads to the increaseof displacements and confining pressure close to the highest strips, while tensileforces are less affected by the load. This leads us to the conclusion that the train speed doesnot have a significant effect on the stability of MSE walls, at least for embankments havingsimilar parameters than the experimental one. However these results strongly depend on theembankment geometry, the way to model the train and the parameters and constitutive lawschosen for the soil, the soil/reinforcement interface and the facing.