Drilled Displacement Piles in the Northeastern United States-Paper

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Drilled displacement (DD) piles are cast-in-place foundations installed with a hollow-stem tool that rotates into the ground, displacing soil laterally, then places grout or concrete as the tool is withdrawn. Auger Pressure Grouted Displacement (APGD) is one such method. Unlike conventional augered piles, DD installation can densify granular soils and increase horizontal stress, improving shaft and toe resistance. The single-pass process produces little noise or vibration and generates no excavated spoil—advantages in urban and contaminated sites.<br /><br />Three northeastern U.S. projects illustrate the method. At an energy facility in Dagsboro, Delaware, 16-inch APGD piles supported 150-ton loads. Compared with the proposed augered cast-in-place piles, they averaged about 20 feet shorter, reduced grout and reinforcing-steel use, and avoided disposal of approximately 4,500 cubic yards of soil. The foundation was estimated to cost 10–20% less.<br /><br />At a medical facility in Camden, New Jersey, 14-inch APGD piles replaced 90-foot driven steel pipe piles. A 70-foot test pile exceeded the required capacity, enabling shorter production piles and avoiding pipe-pile fabrication and delivery delays.<br /><br />At a Woodbridge, New Jersey, energy facility, APGD elements were used as ground improvement beneath structural mats. They densified rubble fill and loose sands to increase bearing capacity and limit settlement, while avoiding soil and groundwater removal and preserving an underlying natural barrier.<br /><br />Automated monitoring equipment records installation parameters in real time. Measures of installation effort can help identify soil conditions and guide pile toe depths to suit variations across a site. Overall, DD piles can improve construction efficiency and foundation performance where ground conditions permit, and DD elements can also serve as ground improvement or liquefaction-mitigation measures.

Keywords

drilled displacement piles

Auger Pressure Grouted Displacement

APGD

cast-in-place foundations

soil displacement

shaft resistance

toe resistance

ground improvement

foundation performance

liquefaction mitigation