A CPT-based model to predict the installation torque of helical piles in sand

ABSTRACT

Helical piles present a possible alternative to driven displacement piles in the offshore sector. While this type of pile is used widely in the onshore environment, design methods tend to be highly empirical and there is considerable uncertainty around the bearing resistance and the installation resistance required to install large diameter piles necessary to resist uplift. The paper combines a theoretical model for estimating torque resistance from the literature with a cone penetration test (CPT)-based model originally developed to estimate the axial resistance of helical piles and to predict the installation torque required to install piles in sand. The model appears to be able to capture the general installation behavior of piles across a range of scales and in various sand states.

KEYWORDS:

• CPT
• helical pile
• offshore
• sand
• torque

Acknowledgment

The author wish to express his thanks to BAUER Maschinen GmbH for granting him permission to publish these results and to Professor Kenneth Gavin (Delft University of Technology) for the precious feedback during the preparation of the manuscript. The laboratory tests at University College Dublin were performed by several staff and students of the Geotechnical Research Group. The assistance of Dr Carl Brangan, Soroosh Jalilvand, and Kate O’Grady is particularly acknowledged.