OasisLMS

Abstract: Although helical piles are effective for both onshore and offshore structures under axial loads, their performance can be compromised due to installation-induced soil disturbance. Among enhancement methods, expanded piles, post-grouting, geometric modifications, conical helices offer recent promise. This study investigates the impact of conical helix geometry on soil disturbance, and axial performance. Six full-scale static load tests were conducted on helical and conical helical piles under both compressive and pullout loads at a coastal site. The test program considered two helix spacing-to-diameter ratios (S/D = 1.5 and 3) and different helix configurations. Ultimate load capacities were interpreted using multiple established criteria and further analyzed using probabilistic methods, incorporating Monte Carlo simulations to account for inherent soil variability. The results demonstrate that conical helical piles enhance load-bearing capacity and reduce installation disturbance, particularly under pullout loading at S/D = 1.5 and compression at S/D = 3. Compared to conventional helical piles, conical variants exhibited higher initial stiffness and limit loads. Moreover, reliability-based design (RBD) analysis revealed that the cylindrical shear method provides more conservative and consistent predictions than the individual plate approach. The investigation concluded that incorporating conical geometry variations minimizes soil disturbance, simplifies installation processes, and enhances the load-bearing capacity of these foundation systems.

Dr. SARA HEIDARIE GOLAFZANI; Engr. Mostafa Nazmi

Annual Conference Proceedings