DFI Journal - The Journal of the Deep Foundations Institute
Volume 15, Issue 2, November 2021
DOI: 10.37308/DFIJnl.20200929.225
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A Small-Scale Experimental Investigation on the Benefits of a Hybrid Pile/Footing System on Sand
Article Type: Research Paper
Maadheedi, M.A., Hytiris, N. & Mickovski, S.B.
Abstract
This paper explores the capacity effects of a square steel plate welded at the ground surface on a driven open-ended steel pile (i.e. the plate would touch the ground surface after the pile achieves the required penetration). A series of strain-controlled, 1-g small-scale laboratory tests were undertaken on piles with and without a square steel plate attached. The piles were driven in dry, loosely packed, uniform sand. Two plates were used, one with a breadth equal to two times the diameter of the pile (2D) and the other with a breadth equal to three times the diameter of the piles (3D). A 20% increase in capacity was recorded for the 2D plate, and a 110% increase in capacity was recorded for the 3D plate when compared to the pile without an attached steel plate. The back-analysis of the results allowed the derivation of a new expression to calculate the capacity of bearing plates and plot its load-settlement profile, which accounted for the effects of sands compaction and dilation. By extrapolating the findings of these tests to a hypothetical scenario, a model design problem was described where the length of a pile can be reduced by 20% to 60% (depending on the load) by using a plate attached to the pile. The results of this study can help designers to minimise penetration depth; thus, achieving a more economical and sustainable design.
Keywords:
Steel piles, pipe piles, deep foundations, ground improvement, hybrid pile/footing