ed on a porous plastic base to allow water flow to
der of the assembled sample container. The nomi-
the sample from an exterior annular reservoir. Ex-
nal sample dimensions were 10 mm in height and
cept for the upper end of the Plexiglas cylinder,
34 mm in diameter. We prepared each sample at
the cylinder and reservoir were surrounded by
room temperature by mixing 12.5 g of the New
insulation. The upper end of the cylinder was left
Hampshire silt with water to form a slurry with
open to the air. The insulated sample containers
an 80% water content. The slurry was poured into
were made to fit into cylindrical cups that were
the Plexiglas cylinder, preloaded and consolidated
supplied with the centrifuge. These cups have
with a vertical stress of 14.1 kPa. Free water ex-
inside dimensions of 98 mm in diameter and 120
pelled at the sample surface was removed. The
mm in height.
dry mass density of the consolidated samples was
approximately 2040 kg/m3. The sample contain-
The test samples comprised a saturated New
Hampshire silt compacted in the Plexiglas cylin-
ers and sample preloading equipment are shown
in Figure 2.
Following the sample preparation, the in-
sulated sample containers were taken to the
coldroom, placed in the centrifuge cups, and
immediately tested. Figure 3 shows the sample
containers in the centrifuge. The radius from
the centrifuge axis to the sample bottom was
0.196 m. To achieve nominal gravity levels of
8 and 32 g at desired reference radii in the tests
(Cooke 1991), the centrifuge was operated at
rotational velocities close to 193 and 387 rpm,
respectively. The effect of Earth's gravity on the
equilibrium orientation of the centrifuge cups was
considered in our calculation of these velocities.
The experiments were conducted with mini-
mal control of the temperature of the sample
and with minimal measurement of the sample
response. Our hope for these preliminary ex-
periments was simply that we could freeze the
samples from the top down. We operated the
centrifuge with the centrifuge chamber closed
to the coldroom atmosphere, and we main-
tained the chamber temperature close to our
desired temperature of 2C by manually turn-
Figure 2. Sample containers and sample preloading equip-
ment.
ing on and off the refrigeration system of the
Figure 3. Sample containers in the centrifuge.
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