Elastoplastic Model for Cemented Soils

This paper presents a model for bonded or cemented soils within the framework of hardening plasticity. The model is based on the concepts that (1) the strength of a cemented soil can be considered to be made up of two components, the usual strength of the soil skeleton and the strength of cementation bonds; and (2) the deformation of the soil is associated with the component of stresses on the soil skeleton (excluding the bonds), as in a reconstituted soil, whereas the cement bonds offer additional resistance at any given strain level. The overall response of the soil under loading can be visualized as two stiffnesses acting in parallel for the given unit strain. Separate stress-strain relations are defined for the two components and they are then combined to give the overall response. The stress-strain relationship for the soil skeleton component is described here using the modified Cam-clay model. A simple model within the elastoplastic framework is proposed for the “cemented” component. The cemented component incorporates strain softening. The input parameters required are minimal, well defined, and easily determined. The model predictions are compared with test data of several soils under drained and undrained triaxial conditions.