Dry granular flows: rheological measurements of the $\mu(I)$-Rheology

TL;DR

This paper develops a rheometrical method to characterize dense granular flows and compares experimental results with the $(I)$ rheology model, addressing challenges posed by shear localization and dilatancy.

Contribution

It introduces a novel rheometry approach using an annular shear cell to study granular flow behavior and validate the $(I)$ rheology model.

Findings

Successful measurement of dense granular flows in an annular shear cell.

Comparison showing agreement between experimental data and $(I)$ rheology.

Insights into shear localization and dilatant behavior in granular materials.

Abstract

Granular materials do not flow homogeneously like fluids when submitted to external stress,but often form rigid regions that are separated by narrow shear bands where the material yields and flows. This shear localization impacts their apparent rheology, which makes it difficult to infer a constitutive behaviour from conventional rheometric measurements. Moreover, they present a dilatant behaviour, which makes their study in classical fixedvolume geometries difficult. These features led to perform extensive studies with inclined plane flows, which were of crucial importance for the development and the validation of the $\mu(I)$ rheology. Our aim is to develop a method to characterize granular materials with rheometrical tools. Using unusual rheometry measurements in an annular shear cell adapted from Boyer et al. (2011), dense granular flows are studied. A focus is placed on the comparison between the present results and the $\mu(I)$-rheology.