CONTRIBUTION À L’ÉVALUATION DE LA PORTANCE DES FONDATIONS SUPERFICIELLES SUR SOL HÉTÉROGÈNE

Abstract

Soil heterogeneity manifests in various forms, such as variations in density, consistency, or geological composition. According to the available studies, research related to determining the bearing capacity of foundations on layered sand substrates is primarily conducted either through small-scale laboratory model tests or traditional approaches involving several simplified assumptions. In light of these challenges, it becomes imperative to develop more accurate models capable of capturing the complexity of heterogeneous soils. This thesis contributes to the study of the bearing capacity of shallow foundations on homogeneous and heterogeneous soils. The first series of numerical simulations focused on evaluating the validity of the superposition theory and analyzing its influence on the bearing capacity calculation of circular foundations embedded in sand. It also investigated the effect of depth in cases where a surcharge is present near an embedded circular foundation. The second numerical contribution focused on calculating the bearing capacity of strip and circular foundations resting on a sand bilayer. The results of this thesis highlighted the Inaccuracy of the superposition hypothesis for a circular foundation embedded in homogeneous sand. Furthermore, the analysis of the depth factors led to the establishment of a simplified relationship to facilitate the evaluation of and under varying conditions. Additionally, the results of the second contribution showed that the bearing capacity of a foundation on a sand bilayer increases with the thickness of the dense layer, particularly for circular foundations. These findings, consistent with previous studies, confirm the importance of the density and thickness of the upper layer in ensuring foundation stability. Finally, the evaluation of the depth factors and for a circular foundation embedded in a sand bilayer, accounting for the presence of a surcharge adjacent to the ground surface, revealed that the influence of the embedment depth of the foundation remains relatively limited. Keywords: bearing capacity, failure mechanism, shallow foundation, layered soil, surcharge, depth factor.