unsuitable soils, the timber pile penetrates the unsuitable soil and
bears its tip into an underlying soil stratum, capable of supporting
the above ground structure.”
Timber inclusions and rigid inclusions both utilize a Load
Transfer Platform (LTP) consisting of structural fill to transfer the
load from the building footings through the inclusion and into
the bearing layer. The timber inclusion differs from a traditional
rigid inclusion in the material being used. While the timber
inclusion is made from pressure-treated lumber, a rigid inclusion
uses unreinforced grout or concrete to transfer the load to
bearing stratum.
Timber inclusions provide many advantages over the
rigid inclusions.
“For one, timber inclusions have shown to be a less expensive
alternative to rigid inclusions,” said Andrew. “Our timber inclusions
have provided cost savings of up to 40%. Secondly, similar to a
driven pile, timber inclusions utilize Wave Equation Analysis to
determine driving criteria. Every timber inclusion is a tested pile
with a measurable capacity with a tip in a known bearing layer.
Rigid inclusions test a small percentage of inclusions (sometimes
as little as one inclusion on an entire job) using costly static load
tests. Furthermore, with varying end bearing elevations, it is
difficult to determine if the tip of the rigid inclusion is set in the
correct bearing layer.”
Timber inclusions will exhibit proper penetration depth with
a penetration resistance. They also work well when dealing with
underlying obstructions.
“When obstructions are encountered, NMC can ‘spud’ the pile
location and dislodge the obstruction, making way for the time pile
to be installed to a proper tip elevation,” said Andrew.
Project challenges
Timber piles were used in lieu of traditional rammed aggregate
piers. NMC purchased timber pilings from Koppers Utility and
Industrial Products. Editor’s note: Read more about Koppers
Utility and Industrial Products on page 93 of this edition of
PileDriver magazine.
“We used our PM25 Junttan hydraulic hammer to install the
timber inclusions. Many other styles of pile driving hammers can
be used for this application,” says Andrew. “We installed over 300
piles for this project. Although not required, NMC performed
dynamic testing with a Pile Driving Analyzer to evaluate the
capacity of the timber inclusions.”
As for challenges, there were definitely a few, including working
with a high ground water table.
“The project ended up raising the bottom of footing elevations
by one foot to keep the tops of piles and Load Transfer Platform out
of the water,” said Andrew.
PROJECT SPOTLIGHT
Established Reputation
Norwalk Marine Contractors has an established reputation
dating back to 1984 when the company was established by
Louis “Skip” Gardella, a local marine contractor.
At the time, Gardella had the foresight to see that the pile
driving industry was becoming more advanced and technical.
In response to the changing and evolving industry,
NMC sought out and invested in staff with extensive experience
in the deep foundation industry.
Over the decades, NMC has grown to become one of New
England’s top specialty geotechnical and marine contractors.
Specializing in deep foundations and support of
excavation, as well as cruise ship and marine terminals, the
company has served many federal, state and local governments,
and numerous commercial and residential clients.
NMC's projects span from along the rugged Northeast
Coast down to Bermuda’s crystal waters.
Licensed in Connecticut, Rhode Island, Massachusetts,
New Hampshire, New York, and Vermont, as well as Bermuda,
NMC was also the first company to bring the stateof
the-art Junttan hydraulic pile driving rigs and hammers
to North America.
ONE NATION, UNDERGROUND, WITH QUALITY ASSURANCE FOR ALL
WE’RE “AMERICAN PROUD” TO PARTNER WITH THE LEADING UTILITY CONTRACTORS IN THE USA.
ST E E L CAS I N G • P I P E P I L I N G • V E R T I CA L S H A F TS • T E L E C O M D U CT, B OX E S & AC C E S S O R I E S
Pittsburgh Pipe • www.pittsburghpipe.com • 800-325-2653
The Right Pipe • Right on Time
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