PIV analysis of the ground behavior at pile tip by vertical load test of model piles with and without expanded bottom as a variable.-PPT Presentation

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The study used model loading tests and particle image velocimetry (PIV) to compare ground deformation around single and grouped straight and belled piles. Tests were conducted in Toyoura sand at 80% relative density under overburden pressures of 100 and 300 kPa. Group-pile spacing ranged from narrow to wide, and observations continued to a pile-head displacement equal to 10% of the pile-tip diameter.<br /><br />For single piles, substantial downward ground displacement occurred near the pile tip for both geometries. The deformation zone widened and became wedge-shaped from roughly 0.5–1.0 pile-tip diameters below the tip. Geometry-related differences were identified in horizontal displacement at 100 kPa, while vertical displacement distributions showed no clear difference between pile types.<br /><br />For pile groups, horizontal displacement in the soil between piles depended on spacing: none was observed in the narrow-spacing case. At medium and wide spacings, horizontal displacement within the group tended to be greater for belled piles than for straight piles, particularly at the lower overburden pressure. No clear geometry-related differences were found in vertical displacement distributions.<br /><br />Overall, pile geometry, spacing, and overburden pressure affected horizontal ground movement. The results highlight the need to account for pile–pile interaction when assessing group-pile behavior.

Keywords

model loading tests

particle image velocimetry

PIV

ground deformation

single piles

group piles

belled piles

pile spacing

overburden pressure

Toyoura sand