The results of the experiments are crude, yet
was also an expected result, since an inertial field
they provide two pieces of information for the
should not directly affect the heat transfer. From
design of equipment for further experiments. First,
the sample height measurements we estimated
the indication that the freezing occurred from the
the average heave of each of the two 8-g samples
top down in the samples suggests that we can
to be approximately 12 mm and the average
proceed with a one-dimensional cylindrical sam-
heave of each of the two 32-g samples to be ap-
ple configuration in our small centrifuge tests,
proximately 3 mm.
and second, the apparent consistency of the lens
The 8-g test samples froze under a stress field
configurations of the 8-g and 32-g samples with
that is approximately similar to the stress field of
corresponding prototype behavior suggests that
an 8-cm column of soil at 1 g, and the 32-g test samples
with control of the experiments the applicability
froze under a stress field approximately similar to
of the centrifuge for frost heave modeling can be
a 32-cm column of soil at 1 g. The differences in the
investigated.
configurations of the interior lenses of the 8-g samples
and the 32-g samples were the most interesting re-
sult of the experiments. In the 8-g samples the ice
lenses did not form in distinct horizontal layers.
CONCLUSIONS AND
The ice clearly formed thin (< 0.5 mm) lenses that
FUTURE EXPERIMENTS
separated the soil particles, but the lenses appeared
A design of a simple frost heave cell for the
randomly oriented. In the 32-g samples, however,
small centrifuge is illustrated schematically in
a horizontal bias to the lens orientation was evi-
Figure 6. The cell will be instrumented with lower
dent. These observations are consistent with an
explanation that might be used for similar observa-
and upper heaters and with temperature and dis-
tions in the upper 4 cm and the upper 16 cm of a
placement measurement sensors. The lower heater
silt column in 1-g freezing tests: that a randomly
will be a thin heating pad mounted onto the bot-
oriented lens configuration can develop in shal-
tom of the centrifuge cup, and the upper heater
low soils that do not have a significant vertical
will be a cartridge heater mounted in a radial-fin
overburden stress, and a horizontally oriented lens
heat sink. A fan will be installed above the heater
pattern can develop in deeper soils that have a
to circulate air past the heat sink fins to the up-
per sample surface. The upper heater will not be
greater overburden stress.
Figure 6. Design of a simple frost heave cell for the small centrifuge. The
diagram show the cross section of the inside of the centrifuge chamber during
operation; the centrifuge rotor arm is not shown.
7
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