Table 3. Field-measured and calculated test data.
Ice
Avg
Strain
Horizontal compressive strength
thick.a
temp.a
ratea
Measureda
Bulk salinity
Bulk brine volume
Bulk porosity
Calculated
C
s1
cm
‰
‰
‰
MPa
MPa
5.501
5.202
36.533
51.184
0.965
0.386
0.517
0.548
156
10.6
38.19
52.87
7.90e7
0.81
154
10.5
5.54
5.20
38.44
36.26
53.10
51.39
1.10e6
0.49
1.03
0.46
0.57
0.60
120
12.9
6.08
5.37
34.18
32.94
49.20
47.97
1.27e6
0.66
1.07
0.52
0.62
0.67
129
10.7
5.94
5.32
38.50
32.04
53.16
51.64
9.20e6
1.00
1.62
1.12
1.10
1.17
152
10.5
5.57
5.21
38.50
36.82
53.16
51.94
1.42e5
1.30
1.81
1.30
1.26
1.35
166
4.2
5.34
5.16
70.67
67.46
82.66
79.20
9.00e5
1.82
2.15
1.86
1.79
1.60
147
5.9
5.65
5.23
56.83
54.36
69.96
67.28
9.10e5
1.86
2.36
2.04
1.95
1.88
154
4.3
5.54
5.20
69.91
66.86
81.96
78.65
1.33e4
2.10
2.33
2.09
2.03
1.83
146
11.8
5.66
5.24
35.72
34.23
50.61
49.12
1.56e4
2.86
3.11
2.70
2.71
3.00
130
5.1
5.92
5.32
63.26
60.85
75.86
73.18
2.16e4
1.88
2.66
2.50
2.45
2.28
161
7.3
5.42
5.18
48.89
46.74
62.67
60.37
3.40e4
3.53
3.41
3.08
3.08
3.17
129
3.4
5.94
5.32
83.08
79.84
93.96
90.54
7.50e4
2.62
2.86
3.13
3.24
2.77
ˇ
ˇ
ˇ
^
ˇ
ˇ
ˇ
^
ˇ
ˇ
ˇ
^
ˇ
ˇ
ˇ
ˇ
^
a = EXXON Test Data
5 = Timco & Frederking, eq 5
1 = Timco & Frederking eq 6 or 7
6 = Timco & Frederking, revised, eq 8
2 = Eq 2
7 = Figure 18's equation
3 = Eq 1
8 = Eq 10
4 = Figure 13's equation
where σc = horizontal uniaxial unconfined com-
From these equations, Timco and Frederking
pressive strength (MPa)
determined SB for each ice sheet tested (Table 3).
ε = strain rate, s1
Then the bulk density of the sea ice was selected
˙
φB = bulk ice porosity (‰).
to be 0.907 Mg/m3. With these determinations
and the average ice floe temperature given in
Timco and Frederking compared σc values de-
Table 3, the expressions provided by Cox and
Weeks (1983) were used to calculate the bulk po-
termined from eq 5 with in-situ, full ice sheet
rosity of each ice sheet. Note that these values
thickness, horizontal, uniaxial unconfined com-
were not provided by Timco and Frederking in
pression tests performed by Exxon on Beaufort
their paper. The missing bulk porosity values were
Sea ice. The Exxon large-scale test data comprised
recalculated along with the bulk brine volume for
ice thickness, average ice temperature, loading
each ice sheet. The values are listed in the left
strain rate, and the measured strength (Table 3).
column of the brine volume and porosity data
Since the bulk porosity of the ice sheets tested
columns in Table 3. The σc strengths measured by
was not provided, the authors had to make these
Exxon and calculated by Timco and Frederking
estimates. To do this, they first included addi-
are compared in Table 3 and shown graphically in
tional data in Figure 11 and, following the same
Figure 12. The regression curve in Figure 13 shows
approach as Cox and Weeks (1974), ran two linear
that the calculated values are generally higher
regression curves through the data. Only slightly
than the measured ones. This offset may be due to
different from the Cox and Weeks equations (Fig.
small- to large-scale scaling ambiguities.
11), the new equations are:
To bring eq 5 into better agreement with the
SB = 13.4 0.174 TF
(6)
Exxon test results, the bulk salinity and brine vol-
ume of each ice sheet were determined using eq 2
for TF ≤ 0.34 cm; and
and 1, respectively. Next, the SB, TA, and φB data
from Tables 1 and 2 and others referenced were
SB = 8.0 0.016 TF
(7)
plotted as shown in Figure 13a. A boresight view
of the data as seen looking into the salinity "win-
for TF > 0.34 cm.
dow" is shown in Figure 13b. This view clearly
7
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