Geotechnical Preliminary Design of Onshore Wind Turbine Foundations

Abstract

A simplified geotechnical design procedure for foundations of onshore wind turbines is often beneficial because it can provide the types and sizes of foundations required to perform financial feasibility analysis of a project, and can also be used for preliminary design. This study presents a simplified method for designing onshore gravity-based foundations based on limited required data, namely, loads acting on foundations, data provided by manufacturers, and soil properties. The detailed design issues that may be essential for the final design are also discussed. A flowchart of the design process is also presented to visualize the geotechnical design of such foundations. The required calculation procedures can be easily carried out either through a series of spreadsheets or simple hand calculations. An example problem explaining the design of onshore wind turbine foundations was presented to demonstrate the proposed calculation procedure. The data used for the calculations were obtained from the literature. The proposed flowchart provides a quick way for the preliminary design of foundations of onshore wind turbine foundations. The foundation system obtained from the preliminary geotechnical design was numerically modeled using Plaxis 3D software. The global stability of the foundation system under Ultimate Limit State (ULS) loads and soil pressure developed under the foundation were calculated. The soil pressure beneath the foundation under Serviceability Limit States (SLS) loads and the total settlement and rotation of the foundation were calculated. The results obtained from the Plaxis 3D software and those obtained from the preliminary design were in agreement.