Experimental and numerical studies on lateral bearing characteristics of innovative gravel-filled canister-monopile (GCM) hybrid foundation

Abstract

In recent years, the monopile foundation is increasingly utilized to support offshore wind turbines (OWT). However, as the OWT becomes larger, a larger monopile diameter is always required to resist lateral loads, resulting in an increase in the construction cost and installation effort of the monopile. Therefore, an innovative gravel-filled canister-monopile (GCM) hybrid foundation is proposed to provide greater lateral bearing capacity of monopile without raising construction cost and minimizing installation effort. The hybrid foundation that integrates an additional canister filled with gravel alongside the monopile, can increase the horizontal bending stiffness and improve soil resistance as the soil beneath the canister. To evaluate the lateral bearing capacity of the GCM hybrid foundation and compare it with the conventional monopile, the model tests as well as the finite element analysis are conducted in this regard. The results show that the hybrid foundation outperforms the monopile in terms of increasing lateral bearing capacity, moment resistance and reducing lateral deformation. Furthermore, a thorough parametric study evaluating the effects of canister dimensions, backfill properties and loading eccentricity on the lateral bearing characteristics of a hybrid foundation are evaluated. Some design suggestions are provided for the further application of the hybrid foundation in OWT projects.