Approche multi-échelles pour la caractérisation mécanique de couches de produits de corrosion d'acier doux

Le travail comprend différents calculs d'homogénéisation en élasticité linaire afin de caractériser le comportement d'échantillons de corrosion d'acier. La première approche a consisté en des calculs d'homogénéisation des milieux aléatoires. Dans une deuxième approche, des calculs de modules effectifs ont été réalisés en employant la Méthode des Eléments Finis. La caractérisation de la microstructure se base sur une campagne expérimentale. La prochaine étape consistera à caractériser et intégrer des effets de non linéarité en s'appuyant sur des essais mécaniques

INJECTION D'UN COULIS DE MICROCIMENT A TRAVERS UN MILIEU POREUX : MODELISATION ET EXPERIMENTATION

In order to describe the basic phenomenon of miscible grout injection in a saturated and deformable porous medium, a general mathematical model is proposed, which accounts for the existing coupling between the fluid flow analysis, the miscible grout transport, and the solid skeleton deformation, leading to a realistic prediction of the injected zone

Fluid flow and effective conductivity calculations on numerical images of bentonite microstructure

International audienceHydraulic conductivities of compacted water-saturated bentonite were computed based on the real microstructure. The Homogenization of Periodic Media approach employed fully acknowledges the heterogeneous and multiscale mi-crostructure of clay, as well as locally varying physical flow properties. Consequently , three levels of description were considered : the microscopic level of clay particles, the mesoscopic level of clay aggregates, mineral grains and inter-aggregate porosity, and the macroscopic level of the sample subjected to fluid pressure gradients in the laboratory. Starting from the local description of fluid flow, the expression of the effective hydraulic conductivity tensor was derived. The soft and dense gels and the open voids may form a connected flow path or remain occluded. The local problems were solved on the microstructure obtained from a digitalized micrograph by image analysis. The contribution to macroscopic flow by the soft and dense gels was investigated in various configurations , and comparisons were made with hydraulic conductivity data for MX-80 bentonite