A new rheological model for thixoelastic materials in subaqueous gravity driven flows

Journal article (2019)

Authors

N. Hermidas Applied Geology - CEG
Joris T. Eggenhuisen Universiteit Utrecht
S.M. Luthi Applied Geology - CEG , Geoscience and Engineering
Research Group
Applied Geology (CEG) (TU Delft)
Thixotropy Clay suspension Gravity flow Viscosity bifurcation
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Published Date

2019

Language

English

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Faculty

Civil Engineering & Geosciences

Department

Geoscience and Engineering

Research Group

Applied Geology

Abstract

A new viscoelastic constitutive model for subaqueous clay-rich gravity flows is presented. It is explained that for the materials which exhibit a minimum in their strain controlled flow curves the structure parameter must be a symmetric function of the strain rate and the stress. Therefore, the destruction of structure within the material is modeled using the dissipation energy. An expression for the elastic strain of the flowing structure is derived. The final set of equations can reproduce the viscosity bifurcation that clay suspensions may exhibit under a given load. This is explained to be important for the prediction of the run-out distance of clay-rich gravity flows. The ability of the model to reproduce the general response of pasty materials to step stress and step shear rate tests is examined. The model requires four empirical parameters. A methodology is presented for obtaining these parameters and power law functions are given for their calculations for a limited rest time of 3000 s. The ability of the model to reproduce the rheological behavior that clay-rich suspensions exhibit under both stress and strain controlled conditions is examined using rheometry tests.