Study of triaxial loading of segregated granular assemblies through experiments and DEM simulations

TL;DR

This paper introduces a body force-based confinement method for triaxial DEM simulations of granular assemblies, validating it against experiments and analyzing strain localization differences in segregated versus mono-disperse particles.

Contribution

It presents a novel position-dependent confinement technique for DEM triaxial tests and a mesh algorithm for accuracy, along with insights into strain localization in segregated assemblies.

Findings

Segregated assemblies show interface acting as a strain barrier.

Smaller particles experience higher shear strain in segregation.

Simulation results match experimental load responses.

Abstract

A simple position-dependent body force-based confinement for simulating triaxial tests using the Discrete Element Method is presented. The said method is used to perform triaxial simulations on mono-disperse and segregated assemblies of glass spheres. The macroscopic load response obtained in simulations is validated with experimental load response. A mesh construction algorithm is presented to check whether the confinement applied in the triaxial simulations is accurate. The particle displacement data obtained from triaxial simulations are used to obtain a particle-wise average strain tensor. This is further used to compare the strain localisation between the mono-disperse and segregated assemblies. It is observed that, in the segregated assembly, the interface between the two particle phases acts as a barrier for strain localisation, and the smaller particles preferentially undergo a higher degree of shear strain on average.