Micromechanics model for elastic stiffness of non-spherical granular assembly

J. J. Dong, Yii-Wen Pan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

This paper presents a micromechanics model for the elastic stiffness of a non-spherical granular assembly. The microstructural continuum model of ideal spherical assembly is extended for non-ideal assembly. The presented work takes the effects of gradation, shape, and preferred orientation into account by introducing a directional distribution function of branch-vector length. The microstructure of a granular assembly is described by the distributions of packing structure, branch-vector length, and particle number per unit volume. These distributions account or the random nature of a realistic granular material. The microfeatures relevant to the description of non-deal particle assembly are elaborated. The influences of various direction-dependent and direction-independent microfeatures on the elastic stiffness are demonstrated. Hypothetical non-ideal granular assemblies are used to study the effects of gradation, shape and preferred orientation. Based on the proposed model, the paper discusses the inherent anisotropy in a non-ideal granular assembly. The presented work also makes use of a generalized static hypothesis to estimate the contact-force distribution for specific microstructure and stress state. With the estimated contact-force and the Hertz-Mindlin contact theory, the elastic stiffness of a particulate assembly can be evaluated. Hence, the effects of geometric fabric and anisotropic stress state on the elastic stiffness can be deliberated. Consequently, the effects of geometric fabric and kinetic fabric of a natural granular material can be evaluated independently. It is shown that the proposed model can reasonably capture the phenomena of inherent anisotropy and stress-induced anisotropy of a non-spherical granular assembly under small strain.

Original languageEnglish
Pages (from-to)1075-1100
Number of pages26
JournalInternational Journal for Numerical and Analytical Methods in Geomechanics
Volume23
Issue number11
DOIs
StatePublished - 1 Sep 1999

Keywords

  • Elastic stiffness
  • Fabric
  • Granular assembly
  • Inherent anisotropy
  • Micromechanics model
  • Stress-induced anisotropy

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