A theoretical approach for axial compressive analysis of helical piles supporting offshore jacket structures

Abstract

Helical piles are extensively employed to support offshore jacket structures and withstand lateral loads through a push-pull mechanism. Nevertheless, there is still a dearth of research on their compressive capacity associated with settlement, especially for multi-helix piles. This limitation impedes the advancement of response-based design methodologies. To address this gap, this study presents a comprehensive unified theoretical framework for analyzing the axial compressive response of multi-helix piles associated with both individual bearing mode and cylindrical shear mode. The analysis framework is based on two key components: (1) a multi-fictitious soil pile model that model effectively integrating the two distinct bearing mechanisms, and (2) a semi-analytical solution for helical pile response derived using the transfer matrix method. Validation against several reported cases demonstrates that the proposed method provides a reliable tool for predicting the axial compressive behavior of helical piles across diverse scenarios, ensuring its applicability to practical engineering design. Furthermore, parametric studies offer valuable insights into the factors influencing pile response and provide practical guidelines for optimizing helix spacing design. This study contributes to advancing the understanding of helical pile behavior and supports the development of more efficient and reliable design methodologies for offshore helical piles.