Field Monitoring and Numerical Analysis of the Reinforced Concrete Foundation of a Large-Scale Wind Turbine

Yanming Zhou,Qian-Feng Gao,Xinxi Liu,Zongwei Deng,Peng Zhang

doi:10.1155/2021/7656613

Abstract

The objective of this study is to examine the performance of the shallow reinforced concrete foundation of a large-scale wind turbine under the influence of environmental loads. A 2 MW horizontal-axis onshore wind turbine supported by a shallow concrete foundation was considered. The foundation stresses, foundation settlements, and static and dynamic contact pressures at various positions of the shallow foundation were monitored from the construction phase to the operation phase in the field. Numerical simulations were also performed to further analyze the behavior of the wind turbine foundation in different cases. The results demonstrate that the responses of the reinforced concrete foundation, i.e., foundation stresses, contact pressures, and foundation settlements, were variables closely related to the wind direction and wind speed. The distribution of foundation stresses suggested that a reasonable design of steel reinforcement cages around the foundation steel ring is important. The dynamic contact pressure of the foundation could reach 5 kPa, so the influence of dynamic wind loads on the foundation response could not be always neglected, particularly for the foundations seated on weak soils. The foundation settlement during the operation phase could be characterized by the logistic model, but its distribution was uneven due to the presence of eccentric upper weight and wind load. The findings would provide guidance for the foundation design of onshore wind turbines in hilly areas.

Highlights

As a clean, safe, and sustainable natural source, wind energy becomes increasingly important in power supply [1,2,3]
Dynamic wind loads are the main forces for a wind turbine, which could produce considerable vibrations and increased stresses, strains, and deformations in the structure, foundation, and subsoil [8,9,10]. erefore, the shallow foundation of a wind turbine in mountainous and hilly regions must show satisfactory performances in resisting large wind loads
Al-Homoud and Al-Maaitah [14] carried out forced vertical vibration tests on shallow foundations resting on sand. e authors reported that the natural frequency increases while the vibration amplitude declines as the embedment depth, degree of saturation, and foundation base area increase

Summary

Introduction

Safe, and sustainable natural source, wind energy becomes increasingly important in power supply [1,2,3]. Erefore, the shallow foundation of a wind turbine in mountainous and hilly regions must show satisfactory performances in resisting large wind loads. Chen et al [17] conducted dimensionless parametric analyses to evaluate the dynamic responses of soil-foundation systems subjected to harmonic horizontal forces and rocking moments. Pham et al [24] analyzed the responses of the shallow foundation of an onshore wind turbine resting on natural or improved ground. It was found that without considering the foundation uplift, the moment on the wind turbine tower is slightly overestimated, while that on the shallow foundation is significantly underestimated for the large soil stiffness He et al [10] conducted structural health monitoring of a 1.5 MW onshore wind turbine foundation with embedded ring.

Study Methods

Numerical Simulation

Results and Discussion

Foundation Settlement