INTERNATIONAL PROJECT SPOTLIGHT
Feeding the beast
The RM 20 gave PKF the ability to double production, but
the onus was on its crew to maintain a steady supply of
piles. Keough and the crew, recognizing the rig’s hyperefficiency,
dubbed this process “feeding the beast.”
It required both physical and mental effort for PKF’s
crew. While the piles arrive on site marked with driving
depths, they do not always match the supplied borings. It
requires the team to choose and manage piles based on how
the others are going in to avoid waste.
PKF was accustomed to being able to revisit driven piles
before splicing because the hammer with leader dangles
overhead and can be repositioned. Using a track-mounted
machine required careful selection of pile sizes and immediate
splicing in areas where driven piles were clustered
several rows deep. PKF rose to the challenge as evidenced
by the crew’s production rate of up to 20 piles installed per
day.
The RM 20 was productive regardless of whether the
piles were plumb or battered. The RM 20 can effectively
drive battered piles because of its adjustable leader, which
can tilt backwards 45 degrees, and forward and sideways
18.5 degrees. The high turning point of the mast provides
stability in even the most extreme inclinations.
A new level of accessibility
Upon evaluating the positioning of the piers and abutments,
in addition to the topography, PKF recognized that
positioning the crane at street level to service the pile driving
operation presented challenges. The RM 20’s ability to
manoeuver on the jobsite proved essential.
“The RM 20 is perfect for this project because you have
high mobility in a confined area,” explains sales director
for North America, Dirk Himborg of Rammtechnik, GmbH.
“The rig has the option to be fitted with a hydraulically
driven mast foot and back jack-ups to facilitate the lifting
and rotation of the undercarriage, which is especially helpful
on uneven surfaces and confined work spaces.”
It was not just the RM 20’s confined space functionality,
but also its ability to navigate challenging terrain, especially
mud. While a crane could have been positioned to
avoid the mud altogether, the problem on PA Turnpike/I-95
Interchange Project was that there was often nowhere to
position it.
Villanti recalled an instance where PKF needed to relocate
the pile driving operation to the other side of a bridge
with a 13.5-foot clearance. The operator hydraulically
tucked the RM 20’s mast down and crawled underneath.
Breaking down and relocating a crane would have been
cost-prohibitive.
HRS 5 hydraulic hammer delivers power surge
PKF had been using the RG 19 T piling rig with a vibratory
hammer in summer 2015 before the RM 20 with an HRS 5
accelerated hydraulic hammer took up a permanent position
on the site. The RG 19 T was driving sheeting and
soldier piles for non-load bearing applications, but traffic
was shifted onto newly constructed facilities in September
2016, prompting the need for a different approach.
The RM 20 can effectively drive battered piles because
of its adjustable leader, which can tilt backwards 45
degrees, and forward and sideways 18.5 degrees
“This is an accelerated hammer so whatever position you
have, you get a double push,” said Himborg. “It gives the ram
weight not only an up push, but also a push down so you
don’t lose any energy. You’re not relying strictly on gravity.”
The HRS 5 delivers up to 53,104 foot-pounds. PKF especially
appreciated the ability to adjust the energy going into
the hammer with the flick of a thumb.
The HRS 5 not only delivers a higher percentage energy
transfer than a traditional diesel hammer, it is also faster,
delivering 50 to 170 blows per minute. The rate was so rapid
that the on-site PennDOT inspector had concerns about
being able to keep track of the pile count. Fortunately, the
RM 20 records the count, which alleviated that issue.
The added power of the RM 20 with HRS 5 facilitated
compliance with an aggressive PennDOT specification,
which requires 20 blows per inch to refusal on bedrock. PKF
was penetrating a silty sand surface, underlain by a tougher
layer of saprolite, which varied in depth. PKF drove 14 by 89
H-piles to dense bedrock at 12 to 80 feet, although 35 feet
was the average. Piles were capped with a heavy-duty steel
tip for added penetration.
66 Q1 2017 www.pilingcanada.ca
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