PILING, DRILLING & FOUNDATIONS
PILE SWAP AND CUSTOM TOOLING SAVES MONEY FOR CONTRACTOR Challenging contract calls for shift in piling type and support from Bauer rigs By Brian M. Fraley
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inde-Griffith Construction Company was called on to assist when the original contractor on a condo project was unable to reach bearing capacity on a test pile program. The end result was a cost-saving switch to Full Displacement Piles (FDP) using a Bauer BG 36 H Drilling Rig and custom tooling. Linde-Griffith – founded in 1909 – was primarily a pile driving contractor until about 20 years ago when it expanded into foundation drilling. “We’ve seen more and more engineers seeking techniques that offer greater capacity with less noise and vibration,” says Linde-Griffith’s Senior Executive Vice President Mike Shannon. In the midst of apartment buildings and businesses, the yellow mast of a Bauer BG 36 H Drilling Rig towered more than 90 feet over the landscape. The Linde-Griffith field crew braved 30-plus-mph winds and single-digit windchills as the linchpin machine of its FDP operation bored through the frosty soil. The Hackensack project started out as a driven pile project. The previous contractor had run a Pile Driving Analyzer (PDA) Test and was unable to reach the design capacity despite installing various pile types to depths of up to 175 feet. The owner and engineer reached out to Linde-Griffith’s John Shannon looking for ideas. Linde-Griffith suggested using FDP piles. Mike Shannon summarizes the FDP technique: “The piles don’t rest on rock here, you get your load bearing because the displacement and compaction of the soil, and grout column build up enough friction to meet capacity.” “The results were impressive when we Static Load Tested the piles,” recalls Shannon. “We were able to achieve the loads they needed with a 55-foot FDP pile.” The switch to FDP piles was also the most environmentally sound choice, according to Shannon. “They did all the remediation but still didn’t want any material to be exported,” he says. “FDP allowed us to keep all soils in the ground where they belong.”
BG 36 H the centrepiece drill
The FDP operation revolved around the BG 36 H Drilling Rig. Linde-Griffith owns a fleet of drilling
rigs, including two Bauers acquired from Equipment Corporation of America’s (ECA) New York/New Jersey branch. It was January 2018 when the BG 36 H executed test piles at Hackensack. The original plan was to have two rigs driving the FDP operation. The other was to be a BG 28 H. By the time permitting and environmental delays had been cleared, Linde-Griffith’s BG 28 H was tied up on other projects. It was agreed that the BG 36 H would be the only drilling rig on site. Linde-Griffith worked with ECA to equip the BG 36 H with 510-mm (20-inch) FDP Tooling to drill 1,322
FDP piles from 52 to 57 feet. Each pile consisted of a 20-inch grout column with a 10-inch-by-1/4-inch hollow pipe in the centre to provide additional shaft friction. The FDP piles created enough shear and base resistance so landing the pile on competent rock was unnecessary. Linde-Griffith executed each FDP pile in a sequence. First, the displacement tool bored down to the desired depth to loosen and densify the surrounding soil, leaving an open excavation. 4 1/2 to 5 1/2 cubic yards of 5,000-psi grout was then pumped into each hole under pressure through a hollow drill stem as the BG 36 H extracted the displacement tool. MAY 2020
“Our decision to bring in the larger 20-inch full displacement tooling combined with the quality control this machine offers made this project.” Mike Shannon
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