Particle mechanics approach to continuum constitutive modelling

Abstract

A new type of constitutive model is proposed for soils, based on three foundations. The first foundation involves a new approach to Cauchy’s concept of stress, based on a way of organizing particle mechanical information. This leads to a description of effective stress that is consistent with Terzaghi’s principle but contains more information than a tensor. The second foundation involves the load-spreading and displacement-spreading effects of particles in an aggregate. The third foundation takes account of recent proposals in the thermomechanics of granular media. A simple model is then proposed based on expectations inferred from published data of asymptotic proportional straining. Validation calculations are presented showing realistic predictions for monotonic and cyclic plasticity, critical states, dilation, induced anisotropy and non-coaxiality as a result of principal axis rotation. The model suggests that a yield envelope, plastic flow and critical states are not fundamental properties but emergent ones. The paper concludes with a brief discussion of possibilities for further developments.