Analysis of a Single Pile under Vertical and Torsional Combined Loads in Two-Layered Nonhomogeneous Soil

摘要

Pile foundations are inevitably subjected to combined vertical-torsional (V-T) loadings in offshore engineering contexts. This article proposes an analytical method for calculating the V-T response of a single pile in two-layered nonhomogeneous soil. First, the results predicted by this new method are validated against experimental data and found to be in good agreement. The behavior of a single pile under combined V-T loads is then subjected to a parametric study, exploring a range of dimensionless parameters related to the thickness of the top layer, the embedment depth of the foundation (or pile length), the relative pile-soil stiffness, soil profiles, and the level of vertical or torsional load mobilization. This reveals two interesting features of the behavior of a pile under combined V-T loads: (1) the loading path (loading sequence) has an effect on load response and deformation; (2) the length-diameter ratio, soil profile parameters, and relative pile-soil stiffness have a significant effect on the behavior of pile under combined V-T loads, but the top layer thickness has a minimal effect.