A simple elastoplastic hardening constitutive model for EPS geofoam

Expanded polystyrene (EPS) geofoam is increasingly being used as a construction material of choice in situations where its mechanical properties—such as its extremely low density, volume contraction under deviatoric compressive loading, and existence of post-yielding strain hardening—can be exploited. In this paper, a simple elastoplastic hardening constitutive model of EPS geofoam is formulated to model the mechanistic behaviour of EPS geofoam taking into account the characteristic properties of EPS. The model is based on experimental results from a series of triaxial tests performed on EPS samples for confining pressure ranging from 0 to 60 kPa at room temperature (23 °C). Behaviour under higher temperatures is currently under investigation and will be addressed in a future publication. The model has a total of six independent parameters and can be calibrated from data obtained from triaxial tests. It is shown that the constitutive model is able to correctly replicate the characteristic behaviour of the EPS geofoam under shearing. The model is relatively simple to incorporate into numerical codes for geotechnical analysis.