Constitutive response predictions of both dense and loose soils with a discrete element model

Abstract

The capability of a discrete element model to predict the constitutive response of a soil is investigated in this paper. The discrete model is constituted of spherical particles with a contact law embedding inter-particle rolling resistance. The study has been carried out in a constrained framework: the complexity of the model is limited in favour of its simplicity of use, the model calibration is independent of the initial state of the soil, the validation of the model has to be robust in the sense that validation loading paths should differ strongly from the calibration loading paths. To reach these objectives, the contact law of the model was slightly enriched with the implementation of a non-constant friction angle, and both porosity and connectivity are controlled for the numerical simulation of the initial soil state. Numerical predictions of the model on the validation loading paths show that such a modelling framework, associating the model itself and the preparation methodology of the numerical sample, leads to good qualitative and quantitative predictions. This is the case in particular for non-rectilinear loading paths or loading paths involving rotation of principal stress axes, while the model is calibrated from monotonous drained triaxial compressions only.