(3) forecast the prospective depths of piles
punching through limestone layers from
friction-pile calculations; and (4) appraise
the frequency of piles encountering karst
from borings or geophysics.
Benefits of statistical analytics
The benefits of applying statistical analytics
to selecting of test-pile locations, and
ultimately to forecasting production-pile
lengths, is that the risk for variations in pile
length and capacity can be better evaluated
and planned. This approach should lead
to fewer spliced piles, and fewer piles with
multiple splices, and more confident forecasts
of cost and schedule. Moreover, the
reliability of piles during the service life of a
bridge will improve due to the reduction in
drivable splices and the potential for excessive
driving stresses in the concrete piles.
Additionally, repair and maintenance of
piles during construction can be minimized
because dynamic stresses on the piles during
pile driving can be reduced. t
Gregory B. Baecher, Ph.D., is a Life Member
of ASCE and the Glenn L. Martin Professor
of Engineering at the University of Maryland
in College Park, Md. He is a geotechnical
engineer specializing in risk, reliability and
statistical data analysis. He can be contacted
at gbaecher@umd.edu.
Ross T. McGillivray, P.E., is a Life Member of
ASCE and a senior consultant at Ardaman
& Associates, Inc. in Tampa, Fla. He is a geotechnical
engineer specializing in pile design
and construction, mining geotechnics and
ground remediation. He can be contacted at
rmcgillivray@ardaman.com.
Thomas M. Waits, P.E., M.ASCE, is senior
technical advisor, bridges, with HighSpans
Engineering, Inc. in Tallahassee, Fla. He
is a structural engineer specializing in
design, inspection, analysis, and project
management of complex bridge structures
projects. He can be contacted at
twaits@highspans.com.
TECHNICAL
The actual variability in pile-tip elevation within each pier
group, however, is dramatic, and was not forecast during
design. The longest piles in each pier group are as much as
four times as long as the shortest … The extreme variability
of the production pile lengths, even within the same pier
group, led to unanticipated cost overruns and claims.
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