Failure in granular materials based on acoustic tensor: a numerical analysis

¹ DICATECh, Politecnico di Bari - Via Edoardo Orabona, 4, 70126 Bari (Italy)
² CME, University of Twente - P.O.Box 217, 7500AE Enschede (Netherlands)

^* e-mail: giuseppina.recchia@poliba.it
^** e-mail: h.cheng@utwente.nl
^*** e-mail: v.magnanimo@utwente.nl
^**** e-mail: luigi.laragione@poliba.it

Published online: 7 June 2021

Abstract

We investigate localization in granular material with the support of numerical simulations based upon DEM (Distinct Element Method). Localization is associated with a discontinuity in a component of the incremental strain over a plane surface through the condition of the determinant of the acoustic tensor to be zero. DEM simulations are carried out on an aggregate of elastic frictional spheres, initially isotropically compressed and then sheared at constant pressure p₀. The components of the stiffness tensor are evaluated numerically in stressed states along the triaxial test and employed to evaluate the acoustic tensor in order to predict localization. This occurs in the pre-peak region, where the aggregate hardens under the circumstance to be incrementally frictionless: it is a regime in which the tangential force does not change as the deformation proceedes and, consequently, the deviatoric stress varies only with the normal component of the contact force.