Time-dependent rheological properties and thixotropy of reconstituted debris-flows samples taken from channel bank deposits are examined using a commercial rheometer equipped with a vane rotor geometric system. Sweep tests and creep tests were carried out involving mixtures having different grain concentrations ranging between 50% and 58%. Different initial conditions of the mixtures were considered in order to analyze the effects of aging and rejuvenation (thixotropy) over a short period of time and long period of time. Tested slurries show viscosity bifurcation, yield stress and time-dependent behavior. According to the experimental results, three different regimes were identified: a lower shear rate regime, corresponding to a shear rate lower than the critical value; an intermediate banding shear rate regime characterized by static and dynamic yield stress level; and a higher shear rate regime where the flowing debris behaves as a non-Newtonian fluid characterized by a constant steady state ultimate apparent viscosity. In any case, the initial state of the mixture and the sediment concentration affects the ultimate steady state rheology and the time-dependent (thixotropy) slurries’ behavior.

Schippa L., Doghieri F., Pellegrino A.M., Pavesi E. (2021). Thixotropic behavior of reconstituted debris-flow mixture. WATER, 13(2), 1-18 [10.3390/w13020153].

Thixotropic behavior of reconstituted debris-flow mixture

Schippa L.
Primo
;
Doghieri F.
Secondo
;
Pavesi E.
Ultimo
2021

Abstract

Time-dependent rheological properties and thixotropy of reconstituted debris-flows samples taken from channel bank deposits are examined using a commercial rheometer equipped with a vane rotor geometric system. Sweep tests and creep tests were carried out involving mixtures having different grain concentrations ranging between 50% and 58%. Different initial conditions of the mixtures were considered in order to analyze the effects of aging and rejuvenation (thixotropy) over a short period of time and long period of time. Tested slurries show viscosity bifurcation, yield stress and time-dependent behavior. According to the experimental results, three different regimes were identified: a lower shear rate regime, corresponding to a shear rate lower than the critical value; an intermediate banding shear rate regime characterized by static and dynamic yield stress level; and a higher shear rate regime where the flowing debris behaves as a non-Newtonian fluid characterized by a constant steady state ultimate apparent viscosity. In any case, the initial state of the mixture and the sediment concentration affects the ultimate steady state rheology and the time-dependent (thixotropy) slurries’ behavior.
2021
Schippa L., Doghieri F., Pellegrino A.M., Pavesi E. (2021). Thixotropic behavior of reconstituted debris-flow mixture. WATER, 13(2), 1-18 [10.3390/w13020153].
Schippa L.; Doghieri F.; Pellegrino A.M.; Pavesi E.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/855093
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