Behavior of Sand Compaction Columns Installed in Cohesionless Deposits-Article

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The study uses three-dimensional finite element analysis in PLAXIS to examine sand compaction columns (SCCs) supporting a multiple-column composite foundation in loose-to-medium-dense sand. The model represents a 1 × 1 × 1 m laboratory setup and is validated against published plate-load test results, with predicted axial capacity differing by less than 12%. The analysis varies column spacing (1.5–3.5 times the column diameter), ground relative density (30–60%), column friction angle, and column diameter, assessing load–settlement behavior, bearing capacity, and deformation.<br /><br />Bearing capacity generally increases with the surrounding sand’s relative density and with the SCC sand’s friction angle. Increasing column diameter also improves capacity and reduces settlement. However, spacing has a strong influence: increasing spacing from 2D to 3D reduces capacity and increases settlement in the diameter study. The 3D-spacing configuration shows a notably different load–settlement response across the relative densities examined, including delayed plastic deformation and settlement approaching 70 mm before failure.<br /><br />The modeled ground fails progressively in shear, forming a wedge that extends to the surface and produces heave around the foundation. The authors also present dimensionless relationships intended to help estimate performance beyond the laboratory-scale model.<br /><br />The findings are based on numerical simulations of a confined, small-scale domain; the proposed relationships and observed behaviors require further study at field scale before being applied directly in practice.

Keywords

finite element analysis

PLAXIS

sand compaction columns

composite foundation

bearing capacity

load-settlement behavior

relative density

column spacing

column diameter

shear failure