Force and fabric states in granular media

Farhang Radjai (1)

1 PMMG - Physique et Mécanique des Milieux Granulaires

The plastic flow of granular materials reflects to a large extent the constraints imposed by steric exclusions and mechanical equilibrium at the particle scale. An accurate formulation of these local constraints is the key to a statistical mechanical approach but requires a rich set of state parameters. We show that the constraints can be taken into account in a simple way with a reduced set of anisotropy parameters akin to the lowest-order description of the contact and force networks. We then introduce a model of kinematic jamming defined as a state of saturation in the evolution of the contact network. This model correctly predicts the accessible geometrical states as well as the evolution of the system to a kinematically jammed state. We also show that a harmonic decomposition of shear stress as a function of the anisotropy parameters and phase factors representing the loading history leads to the "fragile" character of force networks.

Mots clés: granular matter; fabric; constitutive behavior; micromechanics; fragile behavior; geometrical states; fabric anisotropy

Domaines: Mécanique des matériaux [physics.class-ph]; Mécanique des matériaux [physics.class-ph]

Farhang Radjai. Force and fabric states in granular media. Powders and Grains 2009, Jul 2009, Golden, United States. ⟨hal-00690045⟩