An equivalent stress implementation of Barcelona Basic Model

The paper presents a novel implementation of the Barcelona Basic Model based on the equivalent stress concept. The Barcelona Basic Model may be regarded as an extension of the Modified Cam Clay model for use with partially saturated soils. This extension is achieved by changing the size of the yield locus in line with changes of suction. The paper presents an alternative way of implementing the Barcelona Basic Model, where the main yield surface remains unaffected by changes of suction, but the stress (alongside the stress-strain relationship) is modified instead. This approach is therefore called an equivalent stress approach. The presented model based on the equivalent stress approach offers the same capabilities and predicts the same soil behaviour as the Barcelona Basic Model; the only difference lies in the implementation of the model, though the end-user would not recognise that. However, equivalent stress offers a new interpretation of unsaturated soil behaviour. It follows that, with the help of the equivalent stress technique, a number of existing models for saturated soils can be easily enhanced to allow for modelling of unsaturated soils.