A model of capillary cohesion for numerical simulations of 3D polydisperse granular media

Vincent Richefeu (1) , Moulay Saïd El Youssoufi (2) , Robert Peyroux (1) , Farhang Radjai (2)

1 LMGC - Laboratoire de Mécanique et Génie Civil
2 PMMG - Physique et Mécanique des Milieux Granulaires

We present a three-dimensional discrete-element approach for numerical investigation of wet granular media. This approach relies on basic laws of contact and Coulomb friction enriched by a capillary force law between particles. We show that the latter can be expressed as a simple explicit function of the gap and volume of the liquid bridge connecting a pair of spherical particles. The length scales involved in this expression are analyzed by comparing with direct integration of the Laplace-Young equation. We illustrate and validate this approach by application to direct shear and simple compression loadings. The shear and compression strengths obtained from simulations reproduce well the experimental measurements under similar material and boundary conditions. Our findings show clearly that the number density of liquid bonds in the bulk is a decisive parameter for the overall cohesion of wet granular materials. A homogeneous distribution of the liquid within the bridge debonding distance, even at low volume contents, leads to highest cohesion. The latter is independent of the liquid content as far as the liquid remains in the pendular state and the number density of liquid bonds remains constant.

Mots clés: capillary cohesion; discrete element approach; shear strength; compression strength

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

Vincent Richefeu, Moulay Saïd El Youssoufi, Robert Peyroux, Farhang Radjai. A model of capillary cohesion for numerical simulations of 3D polydisperse granular media. International Journal for Numerical and Analytical Methods in Geomechanics, 2007, ⟨10.1002/nag.674⟩. ⟨hal-00184828⟩