CHD pile performance, Part I: Physical modelling

The Continuous Helical Displacement (CHD) pile is an auger displacement pile developed by Roger Bullivant Ltd in the UK. It has performance characteristics of both displacement and non-displacement piles due to the nature in which it is installed. Based on field experience, it has been shown that the load-settlement performance of the CHD installed in sand exceeds the current design predictions based upon conservative effective pile diameter and design parameters associated with auger bored or continuous flight auger (CFA) cast in-situ piles. In an effort to gain a greater understanding of the performance of the CHD pile compared with more conventional piling techniques, a programme of model pile testing and associated Finite Element Modelling (the subject of a Companion Paper) in sand was undertaken. The model testing programme established that greater shaft resistance may be developed for CHD piles than had originally been considered. Based upon the results of the model testing, recommendations for more appropriate approaches to the selection of end bearing and shaft resistance factors are made to predict ultimate load capacity in sand.