TM 5-852-4/AFM 88-19, Chap. 4
Pile type: 10BP42
Soil profile 0-1 ft peat, 1-20 7 ft
(bottom of piel silt
Pile length 21.4 ft
Backfill around pile silt-water slurry
Length of pile below surface: 20.7 ft
Avg temp of frozen soil 28F
Pile embedment in frozen soil 15.8 ft
Test performed Feb-May 1961
Pile cased through active zone.
Loading schedule: 10-kip increments at 4-day intervals except load held at 90 kips for 8 days, at 130 kips
for 6 days, at 160 kips for 8 days, at 170 kips for 5 days, at 190 kips for 12 days, and at 200 kips.for 9
days. Test terminated due to failure of hydraulic jack and zero load rebound observed for 3 days.
U. S. Army Corps of Engineers
Figure 4-84. Load-settlement test. 1O-kip increments.
responds
approximately
with
the
permafrost
load increments throughout each test. For longer piles
displacement remaining at point E after removal of the
or lower permafrost temperatures, it may be necessary
load, C to D, and completion of rebound. At a practical
to use longer time intervals; this must be determined by
working load of about 72 kips, obtained by dividing the
test. Figure 4-85 shows the effect of time between load
ultimate load (as defined at the end of this paragraph) of
increments on tangential adfreeze bond failure stress on
about 180 kips by a factor of safety of 2.5, relatively good
6-inch steel pipe piles of 11 to 12 feet embedment in
correspondence may be observed between the
permafrost installed in augered holes backfilled with
computed elastic deflection (curve AB) and the observed
siltwater slurry, tested at permafrost temperatures down
deflection (AC).
to 23.5 'F. It will be apparent that for 10,000-lb
(6) To provide meaningful test data, the
increments held less than about 72 hours, measured
false capacities achieved by rapid rates of loading should
bond strength values for these piles tend to be too high,
be avoided by limiting the rate of load increase. The
requiring application for correction factors obtained from
required time interval between load increments increases
these curves to reduce the results to long term values.
with increase in length of pile embedment, decrease of
Similar relationships may be assumed to apply for other
permafrost temperature, and increase in relative intensity
types of piles. Thus, the observed ultimate adfreeze
of loading.
For piles of less than about 20 feet
bond strength obtained in the load test on a steel pile
embedment, in permafrost warmer than about 24 F load
shown in figure 4-81 is too high because the 10-kip
increments should be maintained for at least 72 hours. It
increments
is simplest to use a uniform period between additions of
4-141
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