Constitutive relations for soil: Present and future

The number of constants is rapidly increasing in constitutive models, and the majority of constants defies physical intuition. More insight is needed into the controlling features of the mechanical behavior of granular masses. It may come from microscopic models. Some classification of variables, constants, etc., is proposed. A next stage in the study of constitutive models is proposed in the form of a conference comparing multi-element computer calculations incorporating such models with carefully performed two- or three-dimensional experiments of typical but simplified non-homogeneous boundary-value problems.