Publication Abstract

Proceedings from the Michael W. O'Neill ACIP Pile Sessions of the 83rd Annual TRB Meeting 2004: Recent Experiences & Advancements in the US and Abroad on the use of Auger Cast-in-Place Piles, (DFI)

The Development and Testing of the ScrewSol Rotary Displacement Pile
N.J. Wharmby

The paper describes the aims of the research project, the development of the system and the subsequent implementation of a new piling technique. The basic aim of the project was to develop a piling system that would improve the capacity of a bored cast in-situ pile, reduce the material consumption and minimize spoil; to generate unit cost and environmental impact reduction. The displacement and densification of non-cohesive soils around a pile is beneficial as it enhances the shaft friction capacity and minimizes spoil. The use of traditional bored piling techniques results in a lower unit capacity than an equivalent driven cast in-situ pile. The fact that driven piles, as with most bored piles, have a smooth or straight shaft means that the transfer of load from the pile shaft to the soil relies upon the relative pile/soil interface friction or adhesion and therefore the capacity of the soil is not maximized. The ScrewSol piling system described in the paper adopts the benefits of the Continuous Flight Auger piling system. However, the load capacity of the pile is enhanced in non-cohesive soils due to the localized soil densification during pile installation. Furthermore, a regular thread is formed down the pile shaft to enhance load transfer to the soil and reduce material quantities. The results of a number of test piles carried out in a variety of soil types are presented. The data demonstrates that significant pile capacity improvements are achieved with corresponding cost and environmental impact reductions.

 article #231; publication #71 (MWO-2004)