Effect of pile spacing in helical pile groups in soft clays under combined loading

Abstract

Helical piles have lately emerged as a viable alternative foundation solution in offshore geotechnical applications. The helical piles are typically installed in groups to resist large loads from the structures and may encounter combined loading due to some factor such as the waves from the water surrounding it. Recent research works on group helical piles focused mostly on piles embedded in sand and their response to individual loading regimes. This research has been carried out to examine the behaviour of the helical pile groups embedded in soft clay subjected to combined uplift and lateral loading considering three different configurations (rectangular, triangular, and square) and different spacings between the helical piles (2 to 5 times the helix diameter). A three-dimensional finite element model is developed to predict the load-displacement response of the group and is validated against the 1 g laboratory scale model test results. The findings from the analyses reveal that the influence of combined loading reduces the lateral capacity of the group helical pile. The spacing between the helical piles also has a substantial impact on the response to combined loading. The role of critical spacing ratio for various configurations has also been discussed in this paper.