Field investigation of a multi-helix pile under tensile axial cyclic loading
Field investigation of a multi-helix pile under tensile axial cyclic loading
Helical piles have been proposed as a foundation solution for offshore wind turbines, particularly for jacket structures and anchoring, due to their numerous advantages, including high uplift capacity, minimal environmental impact during installation, and reusability, among others. Offshore foundations and anchors are subjected to cyclic loading from wind, waves, and currents. Most existing studies on helical piles for offshore applications focus on the monotonic performance of single-helix piles, while the cyclic performance of multi-helix piles remains largely unexplored. To address this gap, the current study focuses on the tensile cyclic and post-cyclic behaviour of a four-helix pile. For this purpose, cyclic and monotonic loading tests were conducted on a four-helix pile in a sandy silt soil. To evaluate the load-transfer mechanism during the tests, strain gauges were installed on the pile, enabling the separation of the contributions of the shaft and helical plates to the overall pile performance. For this study, 50 tensile axial loading cycles were applied to the test pile with Qmin of ~13% QT, and Qmax of 50% QT, where QT is the pile uplift capacity. The main findings from the tests are: (i) a top-down loading transfer mechanism was observed for the monotonic and cyclic tests; (ii) greater displacement accumulation occurred during the first cycles; (iii) the 50 tensile cycles have improved the pile monotonic response.
Amanda Regina Foggiato Christoni; Joao Manoel Sampaio Mathias dos Santos Filho; Thaise Da Silva Oliveira Morais; Cristina De Hollanda Cavalcanti Tsuha
5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)
13 - Developmental foundation and anchoring concepts: hybrid foundations, ring anchors, helical piles, torpedo, shared anchoring
https://doi.org/10.53243/ISFOG2025-579
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