In some wind turbines, it is found that sludge spouting on the tower foundation and the tower is lifted up just after several months have passed from starting service. Common characteristic of those wind turbine towers is that they are anchored to the foundation by anchor ring method. In anchor ring method, ring-shaped base plate welded to the wind turbine tower is expected to act as anchor in the foundation. It is suspected that liquid water may have some effect on such a kind of the anchor system. In this research, the experiments with concrete foundation model is carried out to clarify the mechanism of deterioration of the anchoring performance. The influence of the liquid water, bond between foundation concrete and turbine tower, poredistribution of foundation concrete, and loading speed on the anchoring performance under cyclic loading is investigated. After liquid water ingresses to the foundation through the interface between foundation concrete and turbine tower, the anchoring performance is rapidly deteriorated. Even when the bond between foundation concrete and turbine tower is originally sound, liquid water can ingress to the foundation, and rapid deterioration is caused. Because the pore distribution of the foundation concrete and the loading speed have some influence on the deterioration process, it is concluded that the viscous character of the liquid water acts important role on this deterioration process. Under the existence of water, deterioration is accelerated by water wedge effect, erosion with crushed particle, and cavitation erosion. The flow of water has also act important role on the deterioration process because it keeps undamaged concrete surface of the foundation concrete directly contacting to the anchor plate. Based on the knowledge on the deterioration process, rational countermeasures on design and maintenance are proposed.
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