Development of induced anisotropy during shear deformation of plane granular assemblies is investigated by introducing statistical characteristics of fabric and contact forces. The introduced microstructural parameters are explicitly related to the measure of deviatoric load by considering conditions of static equilibrium. Verification of the relationship between parameters of anisotropy, average forces and external loads is presented based on numerical simulation of tests on plane granular assemblies. The physical significance of introduced parameters of microstructure and their evolution during shear deformations is discussed.

The paper presents a micromechanical analysis of plane granular assemblies of discs with a range of diameters, and interacting according to linear contact force-interparticle compliance relationships. Contacts are assumed to be fixed and indestructible. Macroscopically, the system is described in terms of a two-dimensional analogue of generalized Hooke’s law. Explicit expressions for elastic constants in terms of microstructure are derived for dense isotropic assemblies. It is shown that Poisson’s ratio for dense systems depends on the ratio of tangential to normal contact stiffnesses. The derived expression for Poisson’s ratio is verified by numerically simulating plane assemblies comprising 1000 particles. The effect of density on Poisson’s ratio is investigated using numerical simulations. The theory of dense plane systems is extended to dense three-dimensional systems comprising spheres. Finally, it is shown that Poisson’s result ν=1/4 is recovered for spherical particles with central interactions.

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The paper describes a numerical model that was developed to simulate the response of three instrumented, full-scale, geosynthetic-reinforced soil walls under working stress conditions. The walls were constructed with a fascia column of solid modular concrete units and clean, uniform sand backfill on a rigid foundation. The soil reinforcement comprised different arrangements of a weak biaxial polypropylene geogrid reinforcement material. The properties of backfill material, the method of construction, the wall geometry, and the boundary conditions were otherwise nominally the same for each structure. The performance of the test walls up to the end of construction was simulated with the finite-difference-based Fast Lagrangian Analysis of Continua (FLAC) program. The paper describes FLAC program implementation, material properties, constitutive models for component materials, and predicted results for the model walls. The results predicted with the use of nonlinear elastic-plastic models for the backfill soil and reinforcement layers are shown to be in good agreement with measured toe boundary forces, vertical foundation pressures, facing displacements, connection loads, and reinforcement strains. Numerical results using a linear elastic-plastic model for the soil also gave good agreement with measured wall displacements and boundary toe forces but gave a poorer prediction of the distribution of strain in the reinforcement layers.Résumé : Cet article décrit un modèle numérique qui a été développé pour simuler la réponse de trois murs de sol à pleine échelle, instrumentés, armés de géosynthétique et soumis à des conditions de contraintes de travail. Les murs ont été construits avec un parement de colonnes d'unités modulaires solides en béton et un remblai de sable propre uniforme sur une fondation rigide. L'armature du sol comprenait différents arrangements de matériel d'armature en faible géogrid biaxial de polypropylène. Les propriétés du matériau de remblai, la méthode de construction, la géométrie du mur et les conditions aux frontières étaient par ailleurs nominalement les mêmes pour chaque structure. On a simulé la performance des murs d'essais jusqu'à la fin de la construction au moyen du programme FLAC basé sur les différences finies. Cet article décrit l'implémentation du programme FLAC, les propriétés du matériau, les modèles constitutifs pour les matériaux impliqués et les résultats prédits pour les murs modèles. On montre que les résultats prédits au moyen des modèles non linéaires élastiques plastiques pour le sol de remblai et les couches d'armature sont en bonne concordance avec les forces mesurées à la pointe de la fondation, les pressions verticales sur la fondation, les déplacements du parement, les charges aux joints, et les déformations des armatures. Les résultats numériques obtenus au moyen d'un modèle linéaire élasto-plastique pour le sol a aussi donné une bonne concordance avec les déplacements mesurés du mur et les forces à la pointe, mais ont donné une mauvaise prédiction de la distribution ...

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