Influence of Upper Layer on the Bearing Capacity of a Two-Layered Sand-Gravel Shallow Foundation

Abstract

High accuracy model experiments were performed to study the influence of bearing capacity of a two-layered foundation consisting of sand in the lower layer and gravel in upper layer. The influence of the gravel layer on the bearing capacity of foundation was estimated. Results obtained from these two-layered model experiments were compared to a strain softening elasto-plastic FEM computational model to validate its effectiveness. It was revealed that the bearing capacity of two-layered foundation consisting of wet sand in lower layer decreased with the increase in thickness of gravel layer. It was clarified that the bearing capacity was decreased due to the cohesion in lower layer of model experiments and dried sand of FEM. Scale effect was estimated by some finite element analyses with same ratio between thickness of upper layer and width of loading plate. If the ratio between thickness of upper layer and width of loading plate was 0.5, the bearing capacity showed an increase from the bearing capacity without upper gravel layer when the width of loading plate was more than 1m and thickness of upper layer was more than 0.5m.