Exploring the undrained behaviour of granular clumps after isotropic and Ko-consolidation paths using DEM

This paper investigates the undrained behaviour of granular clumps after isotropic and Ko-consolidation paths using a three-dimensional discrete element method (3D-DEM). Four randomly chosen clumped particles with a wide range of densification indexes, ID, and mean confining stresses, p' were considered. The specimens were sheared to the deviatoric strain, epsilon q of 40 % to reach the critical state (CS) conditions. It was found from the results that a unique critical state line (CSL) was achieved, irrespective of consolidation paths. The micro-mechanical quantities such as the average coordination number (CN) and von Mises fabric in terms of the second invariant of deviatoric fabric, FvM, also reached CS values. Irrespective of the consolidation paths, unique relationships were found between e -log(p ')and CN -log(p '). The stress-fabric joint invariant, KF established a unique relationship with p ' and e, which forms a relationship in the KF -p ' -e space and the projection of this relationship in the e -log(p ') plane confirms the classical CSL. Moreover, the flow potential (uF), stress ratio at instability (eta IS), and average coordination number at instability (CNIS) showed no dependency on the consolidation paths, while a dependency was observed for the second-order deviator fabric, FvM.