Numerical studies of ring foundations on geogrid-reinforced sand

Numerical predictions of the ultimate bearing capacity of ring foundations supported by a sand bed with and without geogrid reinforcement are presented. Numerical analyses of the test models were carried out using the finite element package Plaxis. It is shown that the behaviour of ring foundations on sand beds may be reasonably well represented by the hardening soil model available in the Plaxis package. The hardening soil model parameters were derived from the results of drained triaxial tests. The parameters investigated are the effect of depth of first reinforcement layer, the number of reinforcement layers and reinforcement layer size on the ultimate bearing capacity of ring foundations. The results from the finite element analysis are in very good agreement with the experimental observations. The results of this study showed that the reinforcement had a considerable effect on the ultimate bearing capacity of the ring foundations. It was also shown that ultimate bearing capacity values can, depending on the reinforcement geogrid arrangement, be improved by up to three times that of the unreinforced case for the model arrangements investigated.