Nonlinear response of laterally cyclic loaded pile in cohesionless soil based on conical strain wedge model

The response to environmental lateral cyclic loads is an important design consideration for offshore piles installed in sand. This paper proposes a novel conical strain wedge (CSW) model to simulate the pile-cohesionless soil interaction under lateral cyclic loads. The CSW model enhances the depiction of passive compression soil zone resistance and failure pattern compared to the conventional strain wedge (SW). The developed model is incorporated in a simplified and efficient method to calculate the nonlinear pile response to lateral cyclic loads. The performance of the developed theoretical model is validated by comparing its predictions with observations from several experimental studies reported in the literature. The validated CSW model and its solutions are then employed to elucidate the performance characteristics of the pile-soil system under cyclic loading. The results revealed that: (1) the degradation of soil stiffness is more pronounced at the onset of cyclic loading and the rate of increase in pile response due to degradation diminishes with the increase in the number of loading cycles; (2) as the cyclic load amplitude increases, the increase in pile displacement becomes increasingly severe; (3) the number of loading cycles has greater influence on the response of piles with lower flexural stiffness; and (4) the effect of soil shear strength on the pile displacement becomes significant as the number of loading cycles increases, whereas its effect on the pile maximum bending moment diminishes gradually.