Drilled-In Displacement Piles: Lessons Learned from Case History at JFK Airport in New York-PPT Presentation

PPT Presentation

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The presentation describes the use of drilled-in displacement piles (DDPs) for Delta Airlines’ redevelopment at JFK Terminal 4, where more than 110,000 square feet of new construction is planned. The project required foundations that could be installed near an operating airport, with limited noise and vibration, no drilling spoils, tight clearances, and a short schedule.<br /><br />JFK’s typical ground profile comprises hydraulic sand fill over very soft organic marsh deposits, underlain by glacial sands. A 3D ground model combining historical and new exploration data supported design and construction decisions. Because medium-dense glacial sands were suitable for DDP installation, DDPs were selected alongside driven piles as a potentially faster, less expensive alternative to micropiles with greater geotechnical capacity.<br /><br />The initial DDP design specified 16-inch grout columns, 60-foot lengths, and a permanent central steel shaft and driving plate. Grout was placed under gravity as each pile was installed. Pre-production testing included axial compression, tension, and lateral load tests. Back-analysis indicated substantial contributions from both shaft friction and toe resistance, with an approximate 35% shaft-to-65% toe capacity split. Test results and installation drivability led to a revised production design: piles were shortened to 50 feet, with a 30-foot bond length.<br /><br />Acceptance criteria combined minimum toe elevation and bond length with installation torque and grout-volume requirements. Construction quality control tracked installation times, verticality, torque, and grout take. Production averaged four to five piles per rig per day, with a maximum of nine. Shortening the piles also addressed partial refusal encountered in denser sand layers.<br /><br />The project demonstrated that DDPs can be an effective foundation option in suitable medium-dense or medium-stiff soils. They can offer higher axial capacity, faster installation, and lower costs than micropiles, but their performance depends on ground conditions and rigorous load testing and field quality control.

Keywords

drilled-in displacement piles

DDPs

Delta Airlines

JFK Terminal 4

foundation design

glacial sands

micropiles alternative

load testing

grout columns

construction quality control