Threaded Displacement Piles – A Comparison of the “Screwsol” System with Continuous Flight Auger Piles in Cork, Ireland

The use of threaded displacement piles can offer a more sustainable and geotechnically efficient alternative to traditional bored piles, and in particular, continuous flight auger (CFA) piles. This paper presents the results of static load testing on preliminary test piles installed by McDonnell Foundations and Piling in the centre of Cork City, Ireland using the proprietary “Screwsol” threaded displacement pile system, developed by their sister company, Bachy Soletanche Ltd. The tests were carried out alongside standard CFA test piles to allow direct comparison of the two techniques. The paper discusses the design approach and enhancement of capacity developed through the use of the threaded displacement system and compares the load-settlement behaviour of the two different pile types. In addition to the technical aspects, the environmental benefits of the reduced concrete and spoil volumes in the Screwsol piles compared to CFA piles are presented.