A Review on Conventional and Innovative Pile System for Offshore Wind Turbines

Abstract

This paper includes a brief review of analytical, experimental and numerical studies carried out on conventional and innovative piles subjected to monotonic and cyclic lateral loads. State-of-the-art developments and the important approaches relevant to the field of laterally loaded pile was discussed. The observations from small-scale experiments confirmed that monopiles embedded in cohesionless soil undergoes progressive accumulation of displacement and the rate of accumulation does not approach zero even after 10,000 cycles. The accumulated rotation of the foundations under the offshore loading conditions mainly depends on the characteristics of cyclic loading such as the magnitude of maximum and minimum load during a cycle. The review of existing works showed that there are hardly any studies addressing the effect of gentle seabed slope and also the effect of multi-directional loading on the magnitude of accumulated rotation of rigid monopiles. It is critically suggested to consider the influence of strong vertical loads and moments on stiff monopiles installed on gentle seabed slopes. The current study reveals the use of finned and helical piles in improving the lateral resistance and reducing the pile head deflections. However, further investigations are required to validate their performance in varying soil conditions and also to optimize and ease the design through the development of cyclic p–y curves.