A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials

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...

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Autores principales:	Xiaohui Cheng, Shize Xiao, Alex Sixie Cao, Meiying Hou
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/ae546a05e10c4ece8136428fe81f9690
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spelling	oai:doaj.org-article:ae546a05e10c4ece8136428fe81f96902021-12-02T18:37:12ZA unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials10.1038/s41598-021-99006-42045-2322https://doaj.org/article/ae546a05e10c4ece8136428fe81f96902021-10-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-99006-4https://doaj.org/toc/2045-2322Abstract 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.Xiaohui ChengShize XiaoAlex Sixie CaoMeiying HouNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-11 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Xiaohui Cheng Shize Xiao Alex Sixie Cao Meiying Hou A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials
description	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.
format	article
author	Xiaohui Cheng Shize Xiao Alex Sixie Cao Meiying Hou
author_facet	Xiaohui Cheng Shize Xiao Alex Sixie Cao Meiying Hou
author_sort	Xiaohui Cheng
title	A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials
title_short	A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials
title_full	A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials
title_fullStr	A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials
title_full_unstemmed	A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials
title_sort	unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/ae546a05e10c4ece8136428fe81f9690
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_version_	1718377820939354112

A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials

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