Analysis of Offshore Wind Turbine Rigid Monopile Foundation

An analysis is presented for rigid monopiles using the variational principle of mechanics. The forces acting on the monopile and the soil are considered separately through free-body analysis. The interaction between the monopile and the surrounding soil is taken into account by considering the external and internal forces acting on the monopile-soil system, and the principle of virtual work is used to obtain the equilibrium equations. Two sets of equations, one set describing the pile displacement and rotation and the other set describing the displacements in the soil are derived. The equations are then solved analytically and numerically to obtain the displacements of the monopile and the surrounding soil. The pile displacements obtained from the analysis are in good agreement with those obtained from equivalent three-dimensional finite element analysis. The advantage of using the new analysis is that it produces results fast and do not require any cumbersome input of the problem geometry and mesh.