A Small-Scale Experimental Investigation on the Benefits of a Hybrid Pile/Footing System on Sand-Article

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The study investigates whether attaching a steel bearing plate to a pile can increase foundation capacity and reduce the pile’s required embedment. Researchers conducted small-scale, 1-g laboratory tests using open-ended steel pipes driven into dry, loosely packed Leighton Buzzard sand. They compared piles without plates to piles fitted with square plates two or three times the pile diameter (2D and 3D).<br /><br />Compared with the unplated pile, the 2D plate increased capacity by about 20%, while the 3D plate increased it by about 110%. Surface heaving and soil cracking indicated that the plates acted as shallow footings and compacted the surrounding sand; the larger plate produced more compaction and greater capacity. The authors developed a calculation method that incorporates sand compression and dilation and found it broadly consistent with the experimental load–settlement results.<br /><br />A hypothetical design example suggested that a plate could reduce pile length by roughly 20% to 60%, depending on the load and plate size. This could reduce material use, cost, and environmental impacts, although plates require additional material and installation work.<br /><br />The findings are proof of concept, not yet a basis for direct design. The tests used small models, low stress levels, and a single loose-sand condition, and did not assess group effects or changes in pile shaft resistance. Centrifuge or full-scale tests and field monitoring are needed to validate the approach and investigate scale effects and practical installation methods.

Keywords

steel bearing plate

pile capacity

foundation capacity

embedment reduction

open-ended steel pile

Leighton Buzzard sand

load-settlement behavior

soil compaction

shallow footing effect

centrifuge testing