An appraisal of the influence of material fabric and stress anisotropy on small-strain stiffness

Department of Civil and Environmental Engineering, Imperial College London, Skempton Building, London, UK

^* Corresponding author: cath.osullivan@imperial.ac.uk

Published online: 30 June 2017

Abstract

This paper examines the effect of a non-isotropic, true triaxial stress state on soil stiffness using discrete element method (DEM) simulations. Samples of uniform spheres with a very stable face centred cubic (FCC) are considered to isolate the effect of stress from stress-induced fabric changes. At the same time the anisotropic nature of the lattice fabric enables the effect of fabric on the observed responses to be explored. The elastic or small strain stiffness was determined by applying small amplitude displacement perturbations to the samples and measuring the resultant shear wave velocity. Two different mean stress levels were considered and at both stress levels the magnitudes of the three principal stresses were varied. The data obtained confirm that the stresses in direction of wave propagation and shear wave oscillation have a measurable influence on shear modulus values. The extent of sensitivity depends on the material fabric. The stress component orthogonal to the plane of wave motion has, however, a less marked effect on shear