Mandrel Driven Shell Spliced To Pipe Piles

Shell connected to pipe with B-11
The site for New Jersey Transit's Rail Equipment Maintenance & Service Facility in Kearny, NJ is not suitable for any substantial loads. The soil contained fill and peat in the upper strata, with fine sands and silts below. Deeper, some sands and cobbles overlay red sandstone rock at about 120 feet. Therefore, piles were necessary to carry the load to rock.

Engineers at Seelye Stevenson Value & Knecht determined that 14 inch corrugated shell pile driven to a depth of 110 to 120 feet was appropriate for the site conditions and would satisfy design criteria.

The Guild mandrel that was planned to be used for driving the shell pile could drive only to a depth of 95 feet. In order to install the piles to the specified depth, a solution was needed to configure a means for extending the shell pile. DFP was contacted, and worked on a solution.

Transition attached to shell
DFP designed a special B-11 Transition Coupling that allowed the shell pile to be connected to a length of 12 3/4" pipe pile. It was arranged to have the cast steel coupling welded in place onto 200 pieces of 95 foot shell pile, at the corrugated shell pile plant.

At the jobsite, the 95 foot shell pile sections - with the coupling in place - could be lifted over and driven onto the 20 foot sections of pipe pile. The drive-fit method of attachment was a real time savings benefit. The coupling was carefully designed to transfer energy from the mandrel uniformly onto the pipe. Additionally, the outer surface of the cast steel coupling was flared, in order to "plow" the soil away from the ends of the shell pile. Finally, the coupling was designed to closely fit the flattened end of the shell pile. The bottom of the pipe pile section was closed using a 13 1/4" x 3/4" plate, also supplied by DFP. The entire driven length is designed to be filled with concrete.

B-11 castings ready to ship
Having designed the new coupling, work was begun to build the pattern equipment to make the castings. But six test piles had to be driven before the castings would be available. DFP responded by fabricating the needed six couplings of rolled and welded rings.

Pile design load was 75 tons. Two load tests were done, plus an additional four indicator piles to check driving depth. Production driving began. Each pile site was augered to a depth of 20 - 25 feet. The shell pile was assembled onto the the pipe pile by standing the pipe on a timber mat, placing the mandrel and shell over the pipe, and drive-fitting with the pile hammer.

184 foot leads were used, and the piles were driven with a Vulcan 010 hammer at 32,500 foot pounds. The crane used was a Manitowoc 4000W. At one section of the building site, where power lines interfered with the use of the tall leads, shorter 25 foot sections of standard 14" x .375" wall pipe pile were used. DFP supplied the S-1800 Pipe Pile Splice to be used to connect the sections together. DFP supplied both the splicers and the pile closure plate.

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