Effects of local scouring on capacities of monopile-wheel composite foundations in sand under lateral loading

Abstract

This paper focuses on an innovative foundation type of monopile-friction wheel composite foundations, which aim to enhance the loading performance of offshore wind turbines (OWTs) while mitigating the negative impact of local scouring. The study utilizes numerical simulations to investigate the morphology of local scouring under unidirectional flow. Furthermore, the finite element method is employed to quantify the lateral bearing behavior, considering different scouring parameters, loading point heights, and pre-torsional loads. On this basis, the load bearing ratio of each part of the composite foundation under different scour conditions is also obtained. The results reveal that the horizontal bearing characteristics are significantly influenced by different scour parameters, loading point heights and pre-torsional loads. The local scouring can reduce the bearing capacity by about 38%, with scouring depth having the greatest effect, followed by the scouring angle and extent respectively. Moreover, as the loading point height and pre-torsional load increase, the lateral bearing behavior of composite foundations decreases. Notably, the friction wheel contributes more than 40% to the overall bearing capacity, underscoring its importance. The results provide valuable insights into further understanding the bearing behavior of the composite foundation and its potential engineering applications.