Evaluation of a Numerical Modeling of the Radial Expansion and Axial Loading of a New Bioinspired Deep Foundation in Granular Soil

This study describes the finite element (FE) analysis of a new bioinspired deep foundation system that provides considerably greater friction resistance compared with a conventional cylindrical pile of the same initial dimensions. Greater friction resistance is achieved in the expanded pile through controlled in-ground radial expansion of a portion of the pile shaft. To model the pile expansion stage and subsequent axial loading of the expanded pile, FE models were developed in ABAQUS using the Critical State Soil Mechanics-based (CASM) model to represent dilative behavior of sand during pile expansion and axial loading. The paper describes the analyses conducted to deduce appropriate input parameters for CASM and other considerations of the FE model calibration using experimental pipe expansion and pile load test data. The final numerical model of the expanded pile showed a 370% improvement in axial capacity at a pile head displacement equal to 10% of the pile diameter compared with the control pile and more than a 900% increase in soil lateral stress at the pile-soil interface, which accurately represents the experimental data.