Limit equilibrium theory in calculating screw pile bearing capacity under compression

The problem of calculating the ultimate bearing capacity of a screw pile is studied using the limit equilibrium theory in this paper. Calculation methods for the critical screw pitch and the ultimate bearing capacity under two representative failure modes are proposed. Four key parameters affecting the ultimate bearing capacity are compared and analysed, and design optimisation suggestions are put forward. The results illustrate that the ultimate bearing capacity of the screw pile is mainly affected by the shear strength of the soil, the height of the screw thread and the screw pitch. When designing the screw pile, the height of the screw thread could be increased and the screw pitch reduced to some extent.