Unique Quantification of Critical State in Granular Media Considering Fabric Anisotropy

Abstract

Classic definition on the critical state of granular soils lacks proper reference to the fabric structure developed at critical state. This paper presents a study on the characteristics of critical state in consideration of fabric anisotropy in granular media, based on Discrete Element Method (DEM) simulations and a contact-based fabric tensor. In addition to the unique relation between the critical void ratio and the mean effective stress, we identify a unique relation between the mean effective stress and a fabric anisotropy parameter, K, defined by the first joint invariant of deviatoric stress tensor and the deviatoric fabric tensor. The relation does not depend on the specific loading paths. The two unique relations combine to present a unique spatial critical state line (CSL) in the 3Dl space K-e-p for a granular material whose projection in the e-p plane is the unique CSL in classic critical state theory.