Аннотация
As the demand for renewable energy continues to rise, the wind power industry is shifting its focus from the quantity of installed turbines to higher-capacity installations. Consequently, foundation loads increase when the upper turbine is replaced with a larger one, potentially leading to insufficient connection strength between the tower and the foundation ring. To address this issue, this study proposes two retrofit methods: The internal and external combined-connection methods. These methods aim to enhance the connection strength between the wind turbine tower and the foundation by incorporating anchor bolts, additional foundation rings, and post-cast concrete. Three wind turbine-foundation-soil finite element models were established using ABAQUS: One with the existing foundation, one retrofitted using the internal combined-connection method, and one retrofitted using the external combined-connection method. Under the same wind load, the dynamic responses of the three models were compared to evaluate the effectiveness of the internal and external combined-connection methods for foundation retrofitting. This study shows that the internal and external combined-connection methods effectively reduce the stress levels in the anchor bolts, foundation ring, and foundation, with the external combined-connection method yielding better retrofit results. After retrofitting the foundation using the internal and external combined-connection methods, the maximum stresses in the anchor bolts, foundation ring, concrete, and reinforcement cage were reduced by 35.77% and 41.84%, 34.50% and 38.36%, 23.85% and 27.87%, and 39.23% and 45.38%, respectively. However, although both methods have a beneficial effect on the wind turbine structure, their improvement is limited compared to their impact on the anchor bolts, foundation ring, and foundation.