本研究針對離岸風機單樁基礎於液化地盤下之受震反應進行數值模擬與分析。研究中建立整合 FLAC2D 軟體與 PM4Sand 模型之模擬分析流程；透過單元素反覆單剪模擬，驗證其動力性質與抗液化表現呈現擬合文獻經驗之適用性。進一步引入 NREL 5-MW 參考風機模型，並以系統性之幾何簡化與等效處理配置目標結構系統；經自然頻率檢核後，整體模型呈現合理之動態特徵。 模擬結果顯示，上部結構慣性反應對地盤孔隙水壓發展與剪應力分佈具顯著影響，突顯土壤-結構互制效應於動態受震分析中之重要性。而結構之關鍵反應區段集中於 RNA 至塔柱上半段、塔柱底部至轉接段，及液化層至土層交界面之樁段，為設計檢核與耐震評估上需關注之部位。 綜上所述，本研究建構之模擬分析方法，具液化問題模擬之可行性，並展現離岸風機單樁基礎於液化場址下之受震反應特徵，期能作為後續設計評估與相關研究之參考。 ;This study conducts numerical simulations and analyses on the seismic response of offshore wind turbine monopile foundations in liquefiable ground. A simulation framework integrating FLAC2D and the PM4Sand model was established. Through single-element cyclic simple shear simulations, the model’s capability in reproducing dynamic soil properties and liquefaction resistance consistent with empirical correlations was verified. The NREL 5-MW reference wind turbine model was further introduced, in which systematic geometric simplification and equivalent treatment were applied to configure the structural system. After natural frequency identification, the overall soil–structure model exhibited reasonable dynamic characteristics. The simulation results indicate that the inertial response of the superstructure has a significant influence on the development of pore water pressure and shear stress distribution in the ground, highlighting the importance of soil–pile interaction in seismic response analysis. The critical structural response zones were found in the RNA to the upper tower section, the tower base to the transition piece, and the pile segment at the interface between the liquefied and overlying soil layers, which are key regions to be considered in design verification and seismic evaluation. In summary, the proposed simulation approach demonstrates feasibility in liquefaction analysis and reveals the seismic response characteristics of offshore wind turbine monopile foundations in liquefiable sites, providing a useful reference for future design assessments and related research.
