COMPREHENSIVE
DEEP
FOUNDATION
ANALYSIS
Fugro removes uncertainty
in foundation construction
by establishing confidence,
reliability, and efficiency and
through advanced deep
foundation analysis, quality
control and testing. Using
focused risk management with
calibrated foundation designs and
verified production foundations,
we optimize driven pile design
and construction. We apply
extensive experience with tools
such as wave equation analysis,
traditional top down or O-Cell®
static load testing in conjunction
with dynamic load testing to
produce the best results.
FUGRO LOADTEST
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FEATURE
two weeks before performing a static pile
load test to allow setup to occur and be
reflected in the measurements. However,
setup may continue for longer periods
that have traditionally been considered.
A series of instrumented load tests in
mixed sands and clays in Florida reported
by Bullock, et al (2005) show long-term
increases in axial side resistance for periods
up to several years, trending in a linear
fashion when plotted against time on
a log scale. Figure 3 shows a plot of these
data with axial side resistance (Qs) normalized
by the axial side resistance at a
time of one day after driving (Qs-1d).
Setup is understood by most foundation
engineers as related to dissipation
of transient excess pore water pressures,
and this effect is profoundly important
in fine grained soils. However, there are
other factors that contribute to pile setup,
even in coarse granular soils. These can
include soil aging, a well-known phenomenon
that can be defined as an increase
in strength, stiffness and dilatancy that
is not directly related to a change in density.
Aging effects have been attributed to
cementation (e.g., Mitchell and Solymar,
1984) or creep effects at particle contacts
(e.g., Schmertmann, 1991).
Axelsson (2000) made measurements
on instrumented concrete piles in sand
and concluded that pile driving can generate
strong arching effects around the
Normalized Side Resistance (Qs/Qs-1-d)
2.2
2
1.8
1.6
1.4
1.2
1
0.8
0.1 1 10 100 1000 10000
Time after Initial Driving, days
Figure 3: Pile set-up measurements from five sites in Florida (from Bullock, 2005)
Figure 4: Horizontal pressure measurements on pile sidewall (from Axelsson, 2000)
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