本研究探討風機套筒式支撐結構在土壤液化狀態之受震結構行為。根據2019年「縮尺比例套筒式基礎離岸風機結構模型振動台實驗」成果，本研究以空樁條件（無飽和砂土）模擬土壤因完全液化後失去側向阻抗之極限狀態，探討地震與土壤液化對風機套筒式支撐結構之影響。實驗試體共分為兩組，第一組為前次試體經修復後且保留相同樁長、第二組為主控模態之週期與前次實驗液化狀態相同週期之試體，但改變樁長。此外，亦搭配與前次實驗相同的調諧質量阻尼（TMD）於頂端，本研究之實驗組別包含兩種試體及TMD的開啟與鎖固，共分成四階段進行。輸入地震波為集集地震與花蓮地震，最大檯面加速度由0.1g逐步增加至1.5g。實驗結果顯示，檯面加速度達1.5g時試驗結束，風機套筒式支撐結構已產生永久變形，但結構體本身並無產生肉眼可見之降伏破壞，說明結構並不會受水平地震力所控制。而當土壤液化發生時將造成系統週期與阻尼比等物理量變化，影響結構體之加速度與位移峰值反應。值得一提的是，採用空樁條件（無飽和砂土）進行實驗，隨地震強度漸增過程可模擬土壤完全液化之結構反應，尤其在塔柱位移反應具有非常良好的相似度。因此，液化狀態時土壤之側向勁度及強度可忽略。

This experiment follows the " Shaking Table Test on a Scaled Model of Offshore Wind Turbine on Jacket Foundation " to discuss the effect of soil water in the incomplete soil liquefaction and complete soil liquefaction on the offshore wind turbines structure, and simulate the structural behavior under the soil liquefaction with increasing the seismic force to the extreme under this limit state condition, and observe the reaction change of the structure under the combined action of extreme seismic force and extreme conditions. Besides, it is also equipped with the same seismic mitigation system (tuned mass damping, TMD) as the previous experiment to complete the offshore wind turbine seismic mitigation.
There are two kinds of specimens in this experiment, which are the scale model that has been restored after the previous experiment and the new scale model with the modified length of pile and same superstructure.
The shaking table experiment group includes two specimens and TMD divided into four stages. Analysis and experiment results show that when soil liquefaction occurs, the system period will change, which will affect the physical quantities of the reaction such as damping ratio or peak response. The presence of soil and water will cause a significant impact on the offshore wind turbines structure even if the site condition is complete soil liquefaction during the earthquakes, making the acceleration response intense and suppressing displacement. The results of the specimens simulating the occurrence of soil liquefaction without soil water can have a good fit in the displacement response, and as the seismic force gradually increases to the limit, the displacement response will converge more slowly and slower than the acceleration peak. At the end of the test with a maximum PGA of 1.5g in this experiment, the scaled model wind turbine support structure had permanently deformed, but the structure itself did not cause visible damage, indicating that the structure will not be controlled by horizontal seismic forces.

[1]Support structures for wind turbines,DNVGL-ST-0126，2018
[2]Shiue-Der Lu, Wu-Chi Ho, Wei-Hsien Lu, Che-Kuei Hu, Mei-Lan Chen, Yung-Shun Lien ,”A research on the potential energy of offshore wind power and preferable offshore blocks in Taiwan”，電力工程研討會，2015.
[3]Cheng-Yu Ku, ChienLien-Kwei. 離岸風力機組之基礎支撐型式介紹. 擷取自 Geoengineering & Scientific Computation Lab國立臺灣海洋大學. , Vol. 9, No.8, pp. 625, 2016.
[4]J. Jonkman Butterfield, W. Musial, and G. ScottS. “Definition of a 5-MW Reference Wind Turbine for Offshore System Development”. National Renewable Energy Laboratory. 2009.
[5]樊庭宇、林晉宇、黃金城、朱棟樑，「5MW離岸參考風機桁架式支撐結構之時域疲勞分析與損傷評估」，中國土木水利工程學刊，Vol 30，No.4，頁243-253， 2018。
[6]Shen-Haw Ju, “Design of Large-scale Offshore Wind Turbines with Appropriate Jacket-type Support Structure”. 2019.
[7]薛惠文，「縮尺比例套筒式基礎離岸風機結構模型振動台實驗研究 Shaking Table Test on a Scaled Model of Offshore Wind Turbine on Jacket Foundation」， 碩士論文，國立成功大學土木工程研究所，2019
[8]Lyan-Ywan Lu, Ging-Long LIN, “Experimental study on seismic vibration control of an offshore wind turbine using TMD with soil liquefaction effect”，2020 (In review)
[9]「台灣離岸風機支撐結構設計準則」，財團法人國家實驗研究院國家地震工程研究中心，2018年10月
[10]陳家漢、翁作新，「可能液化地盤中模型樁振動台試驗」，地工技術，第125期，頁35-44，西元2010
[11]Christian Bak, Frederik Zahle, Robert Bitsche, Taeseong Kim, Anders Yde, Lars Christian Henriksen, Anand Natarajan, Morten Hartvig Hansen.“Description of the DTU 10 MW Reference Wind Turbine” DTU Wind Energy Report-I-0092, 2013.
[12]國家地震工程研究中心台南實驗室，https://www.ncree.org/Ncree.aspx?id=4#S。
[13]Ko, Y.Y., Li, Y.T. ,”Response of a scale-model pile group for a jacket foundation of an offshore wind turbine in liquefiable ground during shaking table tests”, Earthquake Engineering & Structural Dynamics. 2020