A micro-mechanical model for the plasticity of porous granular media and link with the Cam clay model

François Bignonnet (1) , Luc Dormieux (1) , Djimédo Kondo (2, 3)

1 multi-échelle - Modélisation et expérimentation multi-échelle pour les solides hétérogènes
2 UPMC - Université Pierre et Marie Curie - Paris 6
3 DALEMBERT - Institut Jean Le Rond d'Alembert

A micro-mechanical constitutive model for the plastic behavior of cohesive granular materials with hardening due to porosity changes is proposed. The plasticity model is based on a re-interpretation of a micro-mechanical strength model for cohesive frictional granular media. The hardening law by porosity changes explicitly stems from the homogenization process. The micro-macro plasticity model, analytical and fully explicit, depends only on two constant material parameters with a clear physical signification at the microscopic scale: the friction angle and the tensile strength of the grain to grain interfaces. The seminal ideas of critical state soil mechanics are retrieved: critical state line, state boundary surface in the stress/porosity space, hardening or softening due to change in porosity and ability to describe both dilatancy and contrac-tancy. The established micro-mechanical model is very similar to the phenomenological modified Cam clay model, providing to the latter a microstructural based interpretation.

Mots clés: ductility; microstructures; porous material; granular material; strengthening mechanisms

Domaines: Mécanique des solides [physics.class-ph]; Matériaux et structures en mécanique [physics.class-ph]

François Bignonnet, Luc Dormieux, Djimédo Kondo. A micro-mechanical model for the plasticity of porous granular media and link with the Cam clay model. International Journal of Plasticity, 2016, 79, pp.259-274. ⟨10.1016/j.ijplas.2015.07.003⟩. ⟨hal-01337763⟩