Comparative analysis of helical pile uplift behaviour in sand using three different constitutive models

This research conducted a comparative study to compare the performance of three constitutive models, i.e., the Mohr-Coulomb model, the Hypoplasticity with intergranular strain model, and the Sanisand model, in assessing the behaviour of helical piles subjected to uplift loading in dry dense sand. Triaxial tests were initially simulated using three models to calibrate their parameters and examine their predictive capabilities. Subsequently, finite element simulations incorporating the calibrated models were developed to replicate a comprehensive series of centrifuge uplift tests. These tests include single-helix helical piles under both shallow and deep embedment conditions, as well as multi-helix helical piles with varying helix spacing ratios. The performance of each model was evaluated based on element-level response, load–displacement behaviour, failure mechanisms, void ratio evolution, and uplift capacity predictions. Comparative analysis of the numerical results against centrifuge test data revealed that the advanced constitutive models, i.e., Hypoplasticity and Sanisand models, provided a more realistic representation of helical pile behaviour under uplift loading conditions. This research concludes that these advanced models offer higher reliability for designing and analysing helical piles, which are increasingly recognised as an efficient foundation solution for offshore structures.