CHD pile performance: part I - physical modelling

The continuous helical displacement (CHD) pile is an auger displacement pile developed in the UK. It has performance characteristics of both displacement and non-displacement piles due to the way in which it is installed. Based on field experience, it has been shown that the load-settlement performance of CHD piles 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 in situ piles. In an effort to gain a greater understanding of the performance of CHD piles in sand compared with more conventional piling techniques, a programme of physical model pile testing (reported in this paper) and associated finite-element modelling (reported in a companion paper) was undertaken. The model testing programme established that greater shaft resistance may be developed for the 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.