On the response of fluidized piles from laboratory model tests in granular soils

Design guidelines of foundation anchors and piles embedded in fluidized sand comprises understanding of installation processes, defining constitutive parameters and establishing analysis techniques. These fundamental aspects have been investigated by a series of laboratory model tests designed to evaluate the mechanism taking place during pile installation through the influence of downwardly-directed vertical water jets in the geometry of fluidized cavities in saturated sands. Measurements indicate fluidization geometry to be controlled by combined effects of jet velocity and the ratio of particle and jet diameters which can be conveniently expressed by the Froude number of particles. Characteristics of the fluidized zone geometry prior and after fluidization indicate considerable reduction of relative density of fluidized samples. Limit equilibrium analysis using geotechnical parameters approaching critical state provided indicative horizontal stress levels to estimate the uplift skin friction of model steel piles.