The Soil Plug Behaviors of Large Diameter Pipe Pile with Restriction Plate-PPT Presentation

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The presentation examines soil-plug behavior in large-diameter, open-ended pipe piles for bridge foundations. These piles can accelerate construction over waterways and provide high load capacity, but their performance depends on reliable soil plugging, and transportation design guidance remains limited.<br /><br />The study evaluates restriction plates installed inside piles to promote plug formation. Researchers combined field installation and load testing, discrete-element modeling, 1-g laboratory experiments, and 50-g centrifuge tests. The models explored plate opening size and shape, grain size, pile diameter, and soil layering.<br /><br />Results indicate that restriction plates increase resistance both directly and by strengthening friction along the pile wall. Smaller openings generally produced greater resistance; multiple small holes outperformed a single opening of equal total area by about 30% in simulations. The plate also promoted a gradually forming, approximately half-spherical soil arch. Larger openings made the arch thinner and less stable. Smaller soil grains provided slightly greater resistance, while thin coarse-grained layers did little to improve bearing capacity.<br /><br />Centrifuge tests showed substantial increases in ultimate bearing resistance compared with unplated piles. Depending on pile diameter and plate configuration, gains ranged from 33% to 167%; four-hole plates generally produced the greatest increases. Full-scale modeling also indicated that restriction plates improve resistance per unit pile area.<br /><br />The study proposes preliminary plug coefficients for unplated piles and piles with one- or four-hole plates, offering a basis for design. The authors emphasize that these recommendations require further validation.

Keywords

soil plug

open-ended pipe piles

bridge foundations

restriction plates

bearing resistance

pile testing

centrifuge tests

discrete-element modeling

soil arching

plug coefficient