A centrifuge study on the effect of embedment on the drained response of shallow foundations under combined loading

Drum centrifuge tests with surface and buried circular footings on medium dense silica sand subjected to planar combined loading are reported. The experimental work specifically addresses the effect of the footing embedment within a work-hardening plasticity approach, which to date has been used predominantly for interpretation of the behaviour of small-scale models of surface foundations. Vertical loading and swipe tests were carried out, and results are compared with existing data from similar studies on small-scale 1g foundation models. The overall trend of the centrifuge results confirms the general framework, suggesting that a work-hardening plasticity approach in terms of force-resultant modelling for the soil footing system (the so-called 'macro-element') applies under properly scaled stress conditions. The data also indicate that the traditional assumption of a yield surface, isotropically expanding with increasing vertical penetration is not suitable for an embedded foundation. An enhancement of the existing yield surface formulation enables generalisation of the existing work-hardening models from surface to embedded footings.