Antonio De Simone
Max Planck Institute for Mathematics in the Sciences (Leipzig, Germany ) and SISSA (Trieste, Italy)
Constitutive models for granular materials with crushable grains

Granular materials have been studied using continuum theories with great successes for more than two centuries. Recently they have been the focus of renewed attention from the point of view of (soft) condensed matter physics. Taking advantage of discrete models of the behaviour of individual grains, a more complete view is slowly emerging, leading to a deeper understanding of the microscopic origin of macroscopic phenomena.

In this process, granular materials with crushable grains enjoy a paradigmatic role in that their granular nature takes centre stage. The observable changes in the mechanical properties of the material encode the evolution of the grain size distribution upon loading. Decoding this correlation is indeed a challenge, with the promise of many rewards. In particular, a detailed microscopic input into macroscopic constitutive modelling seems both necessary and within reach.

In this presentation, some preliminary theoretical work on crushable soils, mostly based on strain-hardening elasto-plasticity [1], and its experimental motivation will be discussed. In fact, it was the observation in a pyroclastic weak rock [2] of stress-dilatancy relationships which were incompatible with classical Critical State Soil Mechanics that prompted our investigation. This is joint work with M. Cecconi, C. Tamagnini (both from University of Perugia), and G.M.B. Viggiani (University of Roma Tor Vergata).

References
  1. M. Cecconi, A. De Simone, C. Tamagnini, and G.M.B. Viggiani, A constitutive model for granular materials with grain crushing and its application to a pyroclastic soil. Int. J. Numer. Anal. Meth. Geomech, 26(15):1531-1560.
  2. M. Cecconi and G.M.B. Viggiani, Structural features and mechanical behaviour of a pyroclastic weak rock. Int. J. Numer. Anal. Meth. Geomech., 2001, 25(15):1525-1557.
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