Cavity expansion model for the bearing capacity and settlement of circular shallow foundations on clay

The use of an ellipsoidal cavity expansion model to estimate the bearing capacity and settlement of circular shallow foundations on clay is presented. The model uses an upper-bound energy approach with contours of constant soil displacement taken to be ellipsoidal within a hemispherical outer boundary. The elastic and plastic work done within the soil are equated to the footing work, with yield being defined using the von Mises' yield criterion. It is shown that, for two different soil rigidities, results are consistent with those obtained from finite-element analyses available in the literature. A relationship between the bearing stress on a circular shallow foundation and its normalised settlement is developed, with an expression provided for the linear working range.