風力發電為再生能源中，技術最為成熟且發展較為快速的發電方式之一。而根據我國之環境條件與施工能量限制，發展群樁基礎作為離岸風力發電之支承基礎為相對較可行的方法之一。由於離岸風機長期承受風力、波浪作用力與海流等側向作用力等反覆載重，將可能造成周圍土壤承載力下降之現象，並進而影響整體結構之安全。
本研究針對群樁基礎埋置於非凝聚性土壤中，受反覆側向載重後之群樁承載之效率行為進行探討。以有限元素法建置ABAQUS程式之數值模型，並導入Kuo (2008)之勁度衰減模型(Degradtion Stiffness Model)之概念進行分析。
經由本研究之方法，可合理的評估不同反覆載重次數與載重大小下群樁效率之折減情形，在半對數座標中，隨載重次數的增加群樁效率將呈現負斜率斜直線之衰減方式；而本研究亦探討了群樁效率受側向位移、樁數以及樁帽對群樁效率之影響，可提供設計離岸群樁基礎時之參考。

Due to the energy crisis we have encountered this decade, the wind power becomes an important resource of electricity. It is the maturest and the most rapid-expanded power generation method in all of the renewable energy. According to the environmental conditions and construction limitation in Taiwan, adopting pile groups is a applicable way to be the foundation of offshore wind turbines.
In this study, we are going to discuss about the group pile behavior under cyclic lateral loading in cohesionless soil. Finite element method and the ABAQUS program are used to calculate the soil-pile system response. Furthermore, the degradation stiffness model was also adopted in this numerical model to consider the loss of soil resistance after cyclic loading caused by winds and waves.
By means of the method which is developed in this study, we can reasonable estimate the foundation behavior and the group efficiency under different loading condition and cyclic number.

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