A double hardening model for sand

TLDR: In this article, an elastoplastic model is established for the initial loading, unloading and reloading of sand, where the plastic strains are described as the sum of two independent parts.

Abstract: An elastoplastic model is established for the initial loading, unloading and reloading of sand. The plastic strains are described as the sum of two independent parts. The most important part of the plastic strains is described by means of a shear yield surface and a non-associated flow rule in which Rowe’s stress-dilatancy equation is incorporated. During continued deformation the shear yield surface changes not only in size but also in shape. Close agreement is obtained with experimental data on yield surfaces. The other part of the plastic strains is purely volumetric. This part accounts for the plastic volume strain in isotropic compression. It cannot be disregarded, particularly in the case of loose sands. Un modele elastoplastique est etabli pour le chargement initial, le dechargement et le rechargement de sable. Les deformations plastiques sont decrites comme la somme de deux parties independantes. La partie la plus importante des deformations plastiques est derite a l'aide d'une surface de cisaille...