Model tests on the bearing capacity of reinforced saturated sand ground

Abstract

The majority of previous studies on the failure mechanisms and design methods for reinforced earth slabs have been based on test results for air-dried or low moisture-content soils. In reality, a state of saturation may be a worst-case scenario for an in-service reinforced soil foundation. The validity of existing knowledge regarding reinforced soil foundations for saturated ground is yet to be examined. In this study, reduced-scale models of reinforced horizontal ground consisting of saturated sands are loaded to failure using a relatively fast displacement rate to explore the mechanism governing the failure of saturated ground. Special focus is placed on the generation of excess porewater pressures, Δu, as a function of the reinforcement placement density (Rd). A theory on the generation of Δu in reinforced saturated ground is proposed based on the stress–strain behaviour of sands. Experimental evidence shows that the maximum tensile strain for a specific layer of reinforcement is located within ± 0.5B of the centreline of a footing of width B, suggesting that maximum tensile strains occur in the deep-footing zone. The maximum reinforcement strains are mobilised in the bottom layer of reinforcement rather than the upper layer. This reflects the small and large shear strains in the zone of deep-footing effect (the A zone) and the zone under the deep footing (the B zone), respectively, as observed previously using a photogrammetric method.