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Geotechnical News • December 2013
33
GEOTECHNICAL INSTRUMENTATION NEWS
sand layer between 7.6 and 9.9 m
depth. The additional tensile capacity
is primarily due to the lower dense
sand layer.
Summary
A new reusable test pile (RTP) has
been developed to improve the design
of driven piles. The RTP measured
blow counts generally agree with other
in situ data. Dynamic measurements
during driving provide insights into
driving forces, energy propagation,
and dynamic and permanent pile dis-
placements. Static measurements dur-
ing pile setup (not shown) and tension
load tests provide insights into pile
capacity and load distribution along
the pile shaft. Further field testing at
additional test sites where full scale
pile load tests have been performed is
underway.
Acknowledgements
The authors wish to thank Califor-
nia Department of Water Resources
(Division of Safety of Dams) and Cali-
fornia Department of Transportation,
especially Tom Shantz, for funding
this work. Thanks to Great West Drill-
ing, Inc., Robbie Jaeger, Bill Sluis and
Daret Kehlet for their assistance in
development and field testing.
Jason DeJong and
Mason Ghafghazi
Department of Civil and Environ-
mental Engineering, University of
California, Davis, CA 95616.
E: jdejong@ucdavis.edu,
E: mghafghazi@ucdavis.edu.
Aravinthan Thurairajah
Golder Associates Ltd., 500-4260
Still Creek Drive, Burnaby, British
Columbia, Canada V5C 6C6.
E: aran_thurairajah@golder.com
Discussion of: "Field monitoring challenges,
Episode 2 Unforeseen movements (depth and magnitude)"
Marcelo Chuaqui and Wing Lam, Geotechnical News, Vol. 31 No. 2, June 2013
Storer J. Boone
The authors present a curious case
related to the use of inclinometers and
survey data for monitoring subsurface
movements. The conclusions and data
suggest that perhaps a few additional
lessons could be learned if the authors
are at liberty to answer a few ques-
tions provided below.
Lesson Learned 2
Lesson Learned 2 states that the field
personnel did not understand that the
inclinometers should be installed into
a stable stratum at the bottom of the
borehole. Fundamental to the stated
communication problems may be
training of the field people and the
financial arrangements for the project
and these issues prompt the following
questions:
• Why were the selected field per-
sonnel installing the instruments
if they did not understand their
purpose and the associated critical
need to install the bottom into a
stable soil stratum?
0
20
40
60
80
100
Displacement (mm)
200
0
-200
-400
-600
Axial Force (kN)
Tip @ 12.82 m depth, Measurement S3
in Clayey Silt @ 10.02 m depth
Tip at 12.82 m depth, Measurement S5
Above Ground
Figure 7. Representative load-displacement curve obtained from tensile load
test.