Numerical study of shallow foundations on calcareous sand

摘要

Results from finite element computations of the response of shallow vertically loaded circular footings resting on calcareous sand under drained conditions are presented. The predictions are based on the use of the MIT-S1 soil model (Pestana & Whittle 1999). A relatively minor adjustment to the model parameters has enabled prediction of the quasi-linear bearing response of centrifuge model tests reported by Finnie (1993), and different failure modes to be distinguished for compressible and incompressible granular materials. Finite element analyses of rigid-based circular foundations have shown that the bearing stiffness (ratio of average applied pressure to imposed settlement) decreased slightly with increasing foundation diameter, whereas in the centrifuge results it was apparently insensitive to the diameter. However, the high compressibility of calcareous sand confirmed a failure mechanism consisting of a compressional bulb of material beneath the foundation; this was in contrast to comparative analyses undertaken with a dilatant siliceous sand, where a classical failure mechanism was observed.