A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials
OPEN ACCESS
Author / Producer
Date
2021-10-04
Publication Type
Journal Article
ETH Bibliography
no
Citations
Altmetric
OPEN ACCESS
Data
Rights / License
Abstract
Granular shear flows exhibit complex transitional regimes that are dramatically affected by the pressure level and shear stress state. New advances in granular shear tests at low pressure have enlightened the understanding of the two granular shear flow transitions: between quasi-static and moderate shear flows, and between steady-state and transient shear flows. However, a unified constitutive model to describe these two transitions is yet to develop. In this work, a simplified and unified model is proposed based on innovative triaxial shear flow tests, using two dimensionless physical variables. Model results validated against experimental data suggest that the shear flow transition between a quasi-static to a moderate Isotach type flow state is highly pressure-dependent. At extremely low pressure, the granular viscosity becomes the primary mechanism, suppressing the quasi-static mechanism even under “quasi-static” shear rates. In transient to steady state granular flow transitions, a mobilized shear stress ratio or mobilized friction coefficient between zero and the critical state ratio for consolidated granular packings is taken into consideration. This is coupled with the mechanism of granular viscosity. These findings have not been discussed before and are of great relevance to granular mechanics as well as space and earthquake engineering.
Permanent link
Publication status
published
External links
Editor
Book title
Journal / series
Volume
11
Pages / Article No.
19669
Publisher
Macmillan Publishers
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Rheology; Granular shear flows; Constitutive model; Microgravity; Low effective stresses
Organisational unit
08809 - Frangi, Andrea (Tit.-Prof.)