Bearing Capacity of Hybrid Skirted Foundations in Silty Sand-over-Clay under Combined VHM Loading

Hybrid skirted foundations have remarkably catered to the escalating demands in larger load-bearing capacity of offshore wind turbines due to its outstanding horizontal load resistance capacity and cost-effectiveness in steel utilization. This study employed numerical analysis to investigate the failure mechanisms of hybrid skirted foundations under combined VHM (vertical, horizontal, and moment) loading in silty sand-over-clay deposit and to quantify its load-bearing capacity. Comparisons are made between previous published data and this study, in terms of the failure mechanisms of hybrid skirted foundations in both layered and single-clay soil, yielding a robust consensus. Then, a parametric study is employed to provide insight into the effects of foundation dimensions, upper sand layer thickness, soil parameters, and load intensity on the load-bearing capacity of the hybrid skirted foundation. The research demonstrates that the sand layer thickness and the aspect ratio of foundations play significant influence on the behavioral characteristics of hybrid skirted foundation in a silty sand-over-clay soil deposit. An empirical approximate expression is suggested to estimate the uniaxial and combined bearing capacity of hybrid skirted foundations in silty sand-over-clay deposits.