Model and numerical analyses of screw pile uplift in dry sand

This study investigated the performance of screw piles under uplift. The screw piles were installed in sand in the laboratory and uplifted to evaluate the effects of the screw thread pitch and relative density of sand on the pile uplift capacity. The uplift capacity was compared with that of the shaft pile using the digital image correlation technique. Discrete element modelling was used to further examine the load-sharing characteristics, axial force, and shaft friction of the screw pile. The results suggest that the screw pile outperformed the shaft pile in terms of uplift capacity, pile–sand interactions, and load transfer. The improved uplift performance is attributed to the screw threads reaching out to a larger volume of sand particles to resist the uplift. An equation was also proposed to determine the uplift capacity.