Environmental Engineering Reference
In-Depth Information
Authors
Experiments
O'Brien and Julien
[OBR 88]
Viscometric tests on natural mudflow deposits
Coussot [COU 97],
Coussot and Piau
[COU 95], Coussot
et al
.
[COU 03]
Couette rheometer on fine mud samples
Coussot
et al.
[COU 98]
Wide-gap Couette
rheometer with
debris-flow
samples
Bardou
et al.
[BAR 03]
Couette rheometer and special rheometers used for
concrete on debris-flow samples
Remaître
et al
. [REM 05]
Couette rheometer on fine mud samples
Major and Pierson
[MAJ 92]
Couette rheometer with fine-grained materials
collected on debris-flow deposits
Martino [MAR 03]
Couette rheometer with natural samples
Schatzmann
et al.
[SCH 03]
Special BMS rheometer with natural samples
Parsons
et al.
[PAR 01]
Flume with artificial mixtures made up of clay, silt,
and sand
Sosio and Crosta [SOS 09]
Couette rheometer on sand and clay samples
Table 1.1.
Experimental investigations conducted on natural materials or nearly natural
materials providing evidence of viscoplastic behavior
of a yield stress entails numerical difficulties in tracking the shape and position of the
yield surface(s) within the flow.
When the bulk is made up of coarse non-colloidal particles, Coulomb friction at
the particle level imparts its key properties to the bulk, which explains (i) the linear
relationship between the shear stress
τ
and the effective normal stress
σ
=
σ − p
(with
p
the interstitial pore pressure)
τ
=
σ
tan
ϕ,
and (ii) the non-dependence of the shear stress on the shear rate
γ
. Some authors have
suggested that in high-velocity flows, particles undergo collisions, which gives rise to
a regime referred to as the frictional-collisional regime. The first proposition of bulk
stress tensor seems to be attributable to Savage [SAV 82], who split the shear stress
into frictional and collisional contributions
τ
=
σ
tan
ϕ
+
μ
(
T
)
γ,
with
T
the granular temperature. Elaborating on this model, Ancey and Evesque
[ANC 00] suggested that there is a coupling between frictional and collisional
processes. Using heuristic arguments on energy balance, they arrived at the conclusion
