Prediction of Bearing Capacity of Ring Foundation on Dense Sand with Regard to Stress Level Effect

Abstract

This paper uses finite-element formulation of the lower bound theorem to determine the bearing capacity of ring foundations on dense sand. The results are validated with the plasticity solutions, numerical analyses, laboratory small-scale model tests, and field plate loading tests available in the literature. The Bolton strength–dilatancy relation is then adopted to consider the dependency of the friction angle on the stress level. For solid circular footings, the present results agree well with centrifuge model tests. However, a considerable discrepancy exists between numerical analyses and centrifuge model tests for the ring foundation, particularly when the radii ratio exceeds .5. An alternative method is proposed, in which a resistance ratio of the ring foundation to the solid circular footing with the same size is applied to an approximate equation for the bearing capacity of the solid circular footing regarding the stress level effect. The proposed approach is verified with centrifuge model tests.