A Review of the Design and Axial Capacity Calculation Practices for Helical Piles

Helical pile is a type of deep foundation consisting of a steel shaft with round steel plates welded to it. Their applications have significantly increased since the late 1990s with the development of high torque generating machines. They are used in solar power plants, boardwalks, retrofitting works, transmission towers, transmission towers, and even residential buildings. Significant advancement has been made over the years using various laboratory tests, field tests, and software simulations to improve the design and strength of helical piles. However, research is still in progress for upgrading their design and predicting their load-carrying capacities. Codes have also been developed by a few countries for their design such as AC358 (the USA), BS 8004:2015 (the UK), CFEM 2006 (Canada), AS-2159:2009 (Australia). Field practices have also been carried out based on design manuals formulated by companies manufacturing helical piles. Currently, no Indian Standard code is available for their application in Indian conditions. In this paper, the most critical design and calculation methods framed by various researchers and the codal provisions have been discussed and compared. An overview of the essential design parameters influencing the helical pile capacity and a design recommendation have been provided which will be helpful in the design practices of helical piles.