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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.

Sludge ejection from the foundation of a wind turbine tower fixed by the anchor-ring method and the resulting sludge buildup have been confirmed to cause the undesirable phenomenon of lifting of the tower. Using specimen that is a pirtial model of the wind turbine foundation, this study investigates the influence of liquid water, differences in W/C, and differences in loading speed, to analyze developing factors on the concrete damage . The results shows that penetration of liquid water from rainfall and snowfall produces a wedge effect, breakdown of the concrete pore skeleton structure, grinding by sludge particle, cavitation and other effects, and leads to rapid deterioration of the anchorage performance of concrete foundation. Based on the knowledge on the deterioration process, rational countermeasures on design and maintenance are proposed.

効率的な劣化調査の実現のため，既設コンクリート構造物に削孔したドリル孔を活用し，塩化物イオンの浸透を検知するモニタリングセンサを孔内に設置する方法について検討を行った。実験によって，既設コンクリートとセンサの境界部における塩分浸透について，エポキシ樹脂の使用により物質移動抵抗性を付与できることを明らかにした。加えて，検討した設置方法を適用したモルタル供試体を用いて塩化物イオン浸透実験を行い，センサが塩化物イオンの浸透を深さ方向に検知できることを確認した。

アンカーリング方式により定着された風車のタワー基礎において，スラッジが噴出し，噴出量が多くなるとタワーが浮き上がる現象が確認された。本研究では，風車基礎の一部をモデル化した試験体を用いて液状水の存在，水セメント 比の違い，加力速度の違いに注目することで，コンクリート損傷の進展原因を解明する。その結果，降雨降雪に由来した。液状水が内部に浸入したことにより，くさび効果，コンクリート骨格破壊，エロージョン，キャビテーション等の作用が生じ，基礎部分におけるコンクリートを急激に損傷させることが明らかになった。

鉄筋腐食ひび割れを有する鉄筋コンクリートはりにおけるせん断疲労挙動を解明するための，基礎的理論の構築を目的とし，コンクリートのせん断力分担分をストラット幅及び角度に及ぼす影響に分離する方法を提案した。せん断スパン内に導入されたひび割れ先端位置を変化させた三次元有限要素解析を行った結果，ストラット幅及び有効圧縮強度係数は，上限荷重比の低下に伴い減少することが明らかになった。静的載荷時，耐力の増加に寄与するひび割れを有するはりは，ストラット幅の減少が支配的な影響を及ぼすことで，繰返し回数の増加に伴い，せん断疲労耐力が急激に減少することが明らかになった。