PROJECT SPOTLIGHT
Many constraints
and many pile
types for Boh Bros.
Construction Co., LLC
Submitted by Boh Bros. Construction Co., LLC
The World Trade Center at the intersection of Canal
Street and the Mississippi River in New Orleans
is being converted into a Four Seasons Hotel and
Residences. Interior renovations plus additions to three sides of
the building are being completed by a joint venture of AECOM
Tishman and Woodward Design + Build of New Orleans. The structural
design was led by Nick Mannix, P.E., manager of Woodward
Engineering Group.
Soil conditions were more variable than desired, but “welcome
to New Orleans.” Very soft clay for the first 30 feet was followed by
sands and silt at 45 feet (some borings had medium-dense sand).
The stiff clay layers changed to dense sand at 90 feet. A test pile program
was conducted on 14-inch open-end pipe piles. PDAs tested
every probe pile at end of initial drive and at various intervals of up
to seven days. Then static load tests, two in compression and two
in tension, followed.
The main addition foundations required over 200 each 14-inch
by 0.250 wall by 110-foot open-end pipe piles. These were driven in
two pieces with a full-penetration weld. Many of these piles were
extremely close to the existing building, which required strategic
planning in order to allow equipment access. After driving, all pipe
piles were filled with sand and topped with concrete to cutoff elevation.
The piles were driven to grade; therefore, open holes posed
a significant hazard to personnel walking through the site. To remedy
the hazard, Boh’s carpentry shop-built hundreds of wooden
pile covers to go over both newly driven piles and to replace countless
covers, which were constantly being damaged by construction
traffic moving through the site.
The most difficult portion of the addition was the riverside. It
was hemmed in between the existing building and the Mississippi
River floodwall with an active railroad track that ran through this
section. Many of the piles in this area were also under an overhang
that could not be removed. The 20-plus highly loaded piles were
14-inch by 110 feet, driven in 13.75-foot. There were also twenty
10.75-inch by 55-foot pipe piles driven in 13.75-foot pieces. The
pipe in pieces were driven by an extended reach forklift. Extra
excitement was caused by the requirement to install sheet piles
under low headroom to provide support for five separate excavations
next to the railroad track. The wales and struts were fabricated
off-site at the Boh Bros. yard and set into the cofferdams after
Photos courtesy of Boh Bros.
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