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SAMC
o
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• ANNUAL REPORT 2013
calculated with the formula Timco and O’Brien (1994)
constructed as an envelope of all data obtained from
experiments with beams of different sizes. Numerical
simulations with Comsol Multiphysics demonstrated
stress concentrations near the beam root in the tests.
Sodhi (1998) introduced tests with fixed end beam for the
calculation of the compressive strength of floating ice
(Figure 21a). Compressive stresses are formed in the
surface layers of the ice in the middle of the beam when
the beam is loaded downward in the middle (Figure
21b). According to proposed scenario, a vertical crack
with depth of about two thirds of the beam thickness
is formed at the beam bottom below the loading point
and provides concentration of compressive stress over
one third of the beam thickness. The maximal load is
reached when the beam is broken by the compression.
We observed the other scenario of beam failure when
it was loaded in lateral direction with the indenter
(Figure 22). A comparison of different failure modes is
shown in Figure 21b and Figure 22b. This demonstrates
the influence of the loading direction on failure mode
of floating ice. Numerical simulations with FEM will
address further interpretation and analysis of the
experimental data in Comsol Multiphysics.
Indentation Tests
Indentation tests were performed in sea ice and fresh
ice with different temperatures and salinity. Tests in
land fast ice with surface temperature about -20ºC and
thickness 75 cm demonstrated creep behaviour of the
ice under nominal pressure above 5 MPa with strain rate
about 0.001 s
-1
. This pressure is two times higher than
uniaxial compressive strength of cylindrical ice cores
taken from the same ice. Tests in warm sea with temper-
ature -1.5ºC and thickness 50 cm ice in the Barents Sea
demonstrated periodic ice failure with ice piling up in
the front of the indenter under nominal pressure above
4 MPa with similar strain rate 0.001 s
-1
. Tests in fresh
ice of 40 cm thickness with surface temperature below
-10ºC demonstrated brittle failure with buckling and
a) b)
Figure 24. Coal quay Kapp Amsterdam in ice season from sea side (a) and inside the cofferdam (b).
a) b)
Figure 23. Indentation test on the drifting ice in the Barents Sea (a). Ice piling up in the front of the indenter (b).