Recent Advances in Calculation of Shaft Resistance of Drilled-Displacement Piles

Abstract

Drilled-displacement (DD) piles are a distinctive class of auger piles installed by using specially designed drilling tools. Although these piles are increasingly being used in different parts of the world, the available design methods rely on empirical rules. This paper outlines a promising approach to quantify shaft resistance of DD piles installed in sand. Finite element analyses (FEAs) performed in this study use a two-surface, plasticity-based constitutive model for sand and involve three distinct analysis stages: pile installation, removal of drilling tool from the ground, and loading of the pile. Based on FEA results, a set of equations that can be used in calculation of the limit unit shaft resistance of DD piles in sand is proposed. Moreover, the shaft resistance available for a DD pile is compared with that available for a nondisplacement (e.g., drilled shaft) and a full-displacement pile installed by monotonic jacking.