Environmental Engineering Reference
In-Depth Information
FIGURE 3.52
Unconfined compression apparatus.
(Figure 3.54),
pocket penetrometer (
Figure 3.55)
,
and the simple shear device. The uncon-
fined compression test (ASTM D2166-00) is described in
Section 3.4.3.
It provides very
conservative values used primarily for correlations.
In Situ Vane Shear Test (ASTM D2573-01)
Purpose
The purpose is to measure
s
u
and
s
r
in situ
in normally consolidated to slightly overcon-
solidated clays in the field.
Apparatus
The field test apparatus is illustrated in
Figure 3.56.
Procedure
A standard 4-in.-diameter boring is made and cased to the desired test depth. A 3-in.-wide
steel vane on a 1-in.-diameter rod is lowered to the test depth (other vane sizes are avail-
able for smaller casing). Spacers at 30 ft intervals center the rod in the casing. The vane is
pushed to a depth 2 1/2 ft below the casing and torsion applied at a constant rate through
a friction-free mechanism, while the torque is measured on a proving ring. Failure is evi-
denced by a sudden loss of torsion; the test is stopped for a short interval and then rerun
to measure
s
r
. Charts give values for
s
u
and
s
r
for the measured torque and vane size used.
