Model Ice Properties
JON E. ZUFELT AND ROBERT ETTEMA
INTRODUCTION
dynamics of ice motion; the strength and defor-
Physical models have long been used to study
mation behavior of ice, as monolithic ice pieces
complex natural processes not readily amenable to
and as particulate accumulations of ice pieces;
analytical formulation or numerical simulation, or
and friction between ice pieces, between water
whose variables of interest are difficult to measure
and ice in its various forms, and between ice and
in the prototype system due to size, areal extent,
materials against which it rubs. Ice modeling
and personnel safety. Ice-cover formation, evolu-
may, in certain situations, need to take into ac-
tion, jamming, and failure can be so categorized.
count thermodynamic processes associated with
They are intrinsically messy, three-dimensional,
ice growth and ice properties, especially ice
and unsteady processes. Moreover, they often are
strength.
difficult to observe, especially from the shoreline,
Though most modeling situations involve sev-
because some parts of the process occur out of view
eral concurrent processes, it may not be possible
beneath the ice surface.
to fully simulate them all. Even in relatively sim-
The first use of a material to model natural ice
ple situations involving simple processes, such as
behavior in scale physical models dates back to
single-phase flow of water in an open channel,
1918 when blocks of paraffin wax were used to
full similitude is seldom achieved. In virtually all
model ice movement on flowing water (USDI
modeling situations it is necessary to identify the
1980). Paraffin blocks were also used in 1949 for
processes of prime importance, to recognize the
the first reported model of ice jamming on the St.
forces that dominate them, and then to scale the
Francis River near Bromptonville, Quebec (FENCO
model and select a model ice to maintain, as
1949). Since then, many alternative materials have
closely as practicable, the same ratios between
been developed and adapted for use as model ice
these forces in the model and at full scale.
in physical models of diverse ice processes.
Ice modeling usually falls into two general cat-
Wuebben (1995) gives a good history of physical
egories: ice-transport (hydraulic) modeling and
models used to study ice jamming processes.
ice-load modeling. For hydraulic modeling, simi-
This report is a compendium of information on
larity of water flow, ice movement, and ice accu-
the types and appertaining properties of model ice
mulation are of primary importance. For ice-load
materials used in physical modeling. It begins with
modeling, similitude of ice forces exerted during
a brief summary of the processes commonly mod-
icestructure or iceship interaction, ice strength,
eled, then reviews the similitude criteria for repli-
ice-piece movement around structures and hulls,
cating those processes. The remainder of the report
friction between ice pieces, and ice piece size are
discusses the properties and effectiveness of vari-
of primary importance.
ous model ice materials.
Thermodynamic processes are very difficult to
simulate at small scale in a physical model. For
example, the entire process of ice growth and for-
ICE PROCESSES
mation that accompanies river freeze-up is very
In addition to the dynamics of water movement,
difficult to replicate in a small-scale model. Repli-
as well as structural loading and response, ice mod-
cation of the complex strength and deformation
eling may involve any of the following processes:
behavior of accumulated ice pieces requires espe-
ice-piece buoyancy; the two-phase (liquidsolid)
cially innovative modeling techniques when the
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