Effects of Local Scouring on Load-Bearing Behaviors of Monopile–Friction Wheel Hybrid Foundations on Sandy Deposit Soil under Lateral Loading

Abstract

This paper focuses on the horizontal bearing behaviors of an innovative type of foundation, the monopile–friction wheel hybrid foundation, for offshore wind turbines (OWTs). First, the scouring morphology of a monopile–friction wheel composite foundation under unidirectional flow is obtained by means of laboratory flume model tests. Then, the effects of key scouring parameters and the height of the loading point are further investigated through numerical simulations in terms of deformations, soil resistance distributions, and bearing ratios. The results indicate that for composite foundations, the effects of scouring parameters and the height of the loading point on the lateral bearing behaviors are not negligible, with the scouring depth having the most significant effect, followed by the scouring angle, and finally the scouring extent. Between them, the friction wheel contributes more than 40% to the bearing capacity while about 50% is borne by the pile side. In addition, the prediction formulas for the bearing ratios are obtained taking into account the scouring pits. The results provide valuable insights into understanding the load-bearing behaviors of composite foundations and their engineering applications.