Gravity Grouted Helical and Displacement Piles in Deeper Applications-PPT Presentation

PPT Presentation

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The presentation challenges common assumptions that helical piles cannot be installed beyond 30–40 feet, will buckle in soft clay, or are too slender for deep applications. Two Boston-area case studies demonstrate that helical and grouted displacement piles can reach depths of 100 feet or more in soft clay.<br /><br />At Logan International Airport, helical piles supported gate-expansion projects, including a stair tower and a jet bridge. Designs used 2.25-inch square-shaft pulldown piles with 8-, 10-, and 12-inch helices and grouted shafts. A wider grout section near the pile head helped limit lateral deflection. Piles were installed in phases between 2015 and 2019, reached lengths of up to 120 feet, and terminated in glacial till. They offered a practical alternative to micropiles in a restricted airport work area.<br /><br />At a South Boston Seaport cogeneration plant, grouted displacement piles supported a new oil-tank foundation beside existing buildings. The project used 3.5-inch steel pipes, displacement paddles, and 8-inch grouted shafts. Piles reached 95 feet, with lengths adjusted based on measured installation torque and capacity. The low-spoil, low-vibration installation method suited the site’s tight access and limited laydown space.<br /><br />The presenters conclude that grouted shafts increase pile diameter, buckling capacity, and frictional resistance, while reducing steel corrosion risk and potentially improving lateral performance. With suitable design and installation controls, deep piles—including those exceeding 100 feet—are feasible in softer clays.

Keywords

helical piles

grouted displacement piles

deep foundations

soft clay

Boston case studies

Logan International Airport

South Boston Seaport

pile buckling

installation torque

lateral deflection