Coefficient of internal strength ()
servations have hindered the collection of field
Angle of internal friction (φ)
data for breakup jams. Advances in remote mea-
Porosity (p)
surement technology may be invaluable in this
Shear force on the underside of the ice cover
regard.
(τ)
Based on experience with soils, one would ex-
Frazil particle diameter (d) and fall velocity
pect that values of porosity and internal angle of
coefficient (Ci).
friction for ice could be developed with some reli-
ability in the future, while it could be difficult to
The ice-jam-related literature was searched for
achieve the same level of reliability for ice cohe-
references to these variables, values of which were
sion. Reliable estimates of frazil particle diameter
collected and reported in the present study. Based
and fall velocity coefficient could be achieved with
on these data, recommended values are shown in
careful study. The primary obstacle in developing
Table 6. At the present time, ice cover roughness,
such estimates appears to be the difficulty in de-
whether for frazil ice or breakup jams, is the only
vising measurement methods for a material close
variable of those listed above that is known
to its melting point.
with any reliability. Much work remains to be
The literature review also provided information
on other hydraulic and physical properties of ice
done to determine reasonable values for the other
jams that are of use to researchers and engineers
variables, especially the coefficient of internal
interested in ice jam hydraulics. These are
strength. Safety issues inherent in making field ob-
Anchor ice growth
Jam erosion
Table 6. Recommended values of hydraulic and
Ice cover velocity
physical properties affecting ice jams.
Coefficient of ice loss
Thermal effects on ice jam
Property
Range of values
Permeability
Ice piece size and distribution.
Ice cover roughness (ni)
Freezeup ice cover
0.0100.060
Recent work in the area of anchor ice growth
Freezeup ice jam
0.0200.10
indicates that a Froude number greater than 0.2,
Breakup (thin ice)
0.0200.10
Breakup (thick ice)
0.0350.15
and preferably larger than about 0.40, is required
for anchor ice growth. Permeability has also been
Cohesion (Ci)
the subject of recent attention, particularly in the
Freezeup ice jam
9601200 Pa
case of grounded jams, where porous flow may
Breakup ice jam
0100 Pa
be important in determining water levels. More
work needs to be done in the area of jam erosion
Coefficient of internal strength ()
1.02.0
and thermal effects on jams, particularly for
freezeup jams. Additional data on the coefficient
Angle of internal friction (φ)
2045
of ice loss could be quite useful in determining
Frazil
4060
jam volume.
Rubble
Porosity (p)
LITERATURE CITED
Freezeup ice jam
0.350.45
Frazil deposit
0.30.6
Andersson, A., and S.F. Daly (1992) Laboratory
Breakup ice jam
0.350.8
investigation of trash rack freezeup by frazil ice.
USA Cold Regions Research and Engineering
Shear force on the underside of
Calculated from
Laboratory, CRREL Report 92-16.
the ice cover (τ)
other data, about
Andres, D.D. (1980) The breakup process and the
1020 Pa
documentation of the 1978 ice jams on the
Frazil particle diameter (d)
110 mm
Athabasca River at Fort McMurray. In Proceedings,
Workshop on Hydraulic Resistance of River Ice, 2324
Frazil fall velocity coefficient (Cf)
1.0
September 1980, Burlington, Ontario, p. 143161.
5-mm- to 1-cm-diameter particles
Andres, D.D. (1999) The effects of freezing on the
25
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