在傳統能源及核能產生的環境問題仍難以解決的情況下，風力發電的低成本與對環境的低汙染特性成為各國重點發展的替代能源之一。台灣位於季風地區，蘊含豐富的風力資源，唯地理位置較為特殊，位在環太平洋地震帶，界於歐亞板塊與菲律賓板塊之間，常有頻繁的地震發生，對於風機設計上需要更嚴謹，且迄今離岸風機支承基礎研究鮮少考慮到土壤液化問題，然而在具有液化潛能土壤區域與地震頻繁之台灣西部外海是不容忽視的問題。
本研究將採用三維有效應力分析模式，針對離岸風機單樁式基礎與管架式基礎進行地震力反應分析，觀察發生土壤液化時對離岸風機基礎的影響，模擬土壤之非線性效應以及樁基礎與土壤間非線性之行為，再藉由Matlab軟體將液化後離岸風機結構頂端受震之加速度進行快速傅立葉轉換，找出離岸風機結構在可液化地層液化後之結構自然振動頻率。
離岸風機單樁式基礎(Yu et al., 2015)離心機試驗與模擬結果在發生液化後之水平加速度與側向位移方面彼此相近，驗證本程式應用在分析離岸風機基礎地盤液化行為之可行性；離岸風機管架式基礎(Passon & Branner, 2014)數值模擬結果顯示液化發生後，若基樁未貫入較堅硬的地層，樁底於地震過程中抑或地震結束後皆有出現明顯滑動。比對各角度地震波入射造成之影響，發現地震波以15度及30度入射對風機基礎影響較大，0度及45度則相對安全，欲開發之離岸風場可根據附近之斷層資料，調整風機底部基礎方位，避免地震波以15度及30度入射。

The purpose of this research is to establish the numerical wind turbine structure model and perform the soil and structure interaction under earthquake loading at the soil liquefaction area. For numerical analysis, original tool was developed by Japanese researcher group (Oka et al., 1994). There are two kind of numerical wind turbine structure in this research. One is monopile wind turbine structure referenced from centrifuge test that Yu et al. (2015) had performed before. Another is jacket wind turbine structure referenced from the result of Passon & Branner (2014).

Comparing the results with numerical analysis and centrifuge test in monopile model, the data show that horizontal acceleration and final lateral displacement of wind tower are quite consistent. We can see that the feasibility of simulating the offshore wind turbine structure is reliable. Whenever the earthquake is happening or has happened, the results of jacket wind turbine structure model show that the bottom of pile is obviously sliding when the piles are not penetrated into the hard layer. It shows that the seismic wave has a great influence on the offshore wind turbine structure at the horizontal incidence angle of 15 degrees and 30 degrees, while the 0 degree and 45 degrees are quite safe. The offshore wind turbine structure foundation can be adjusted according to the nearby fault data to avoid the seismic wave incoming at the horizontal incidence angle of 15 degrees and 30 degrees. The natural frequency of jacket wind turbine structure model is 0.325Hz.

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