Local scouring effects on the bearing capacities of the monopile-friction wheel composite foundation under combined V-H-M loads

Abstract

As an innovative foundation type for offshore wind turbines (OTWs) under complex ocean environments, the monopile-friction wheel composite foundation also has to withstand inevitably combined vertical loads (V), horizontal loads (H), bending moments (M) and local scouring at the same time. To investigate the local scouring characteristics and their effects on the bearing capacity of this new type of composite foundation under combined V-H-M loads, detailed numerical simulations using a combination of CFD software and ABAQUS are completed with qualitative and quantitative analyses presented as well in this paper. The simulation results show that, the scouring hole finally can be simplified to a “U” shape, and the maximum depth is approximately 0.3–1.2 times of the friction wheel thickness, and the maximum extent within twice the wheel diameter. Intensive parametric study is then performed to explore the influences of the scouring angle, depth, extent and pre-applied vertical loading on the failure envelopes in the V-H-M domain. The scouring angle has an enhancing effect on the bearing capacity of the composite foundation, while the increase of scouring depth weakens the performance of the composite foundations.