Divergence Instability and Diffuse Failure in Granular Media

Ali Daouadji (1) , Mohamad Jrad (1) , Florent Prunier (2) , Luc Sibille (3) , François Nicot (4) , Farid Laouafa (5) , Félix Darve (6)

1 LEM3 - Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux
2 LGCIE - Laboratoire de Génie Civil et d'Ingénierie Environnementale
3 GeM - Institut de Recherche en Génie Civil et Mécanique
4 FLUMINANCE - Fluid Flow Analysis, Description and Control from Image Sequences
5 INERIS - Institut National de l'Environnement Industriel et des Risques
6 3S - Laboratoire Sols, Solides, Structures

The question of divergence instability and diffuse failure, which is a common failure mode for granular materials like soils, is tackled here from an experimental, theoretical and numerical perspective. The necessary condition of instability as given by the loss of definite-positiveness of the elasto-plastic matrix (the so-called “second order work criterion”) is considered to analyze some experimental tests leading to diffuse failure, the link between kinetic energy and second order work is established, a discrete element method is used to simulate these failure conditions and eventually a 3D bifurcation analysis is performed with incrementally piecewise and non-linear elasto-plastic relationships. Essentially in relation with the non-associate character of the plastic strains of granular materials, a whole bifurcation domain in the stress space emerges from these analyses, leading to novel views of failure for non-associative materials.

Mots clés: kinetic energy; failure; bifurcation; instability; second order work; non associativeness

Domaines: Mécanique [physics.med-ph]

Ali Daouadji, Mohamad Jrad, Florent Prunier, Luc Sibille, François Nicot, et al.. Divergence Instability and Diffuse Failure in Granular Media. IUTAM Symposium on Linking Scales in Computations: From Microstructure to Macro-scale Properties, 3, Elsevier, pp.115-140, 2012, ⟨10.1016/j.piutam.2012.03.009⟩. ⟨hal-01007504⟩