位於可液化砂土層中離岸風機單樁基礎受震反應的離心模擬;Centrifuge Modeling on the Seismic Response of Mono-Pile Foundations for Offshore Wind Turbines in Liquefiable Sandy Soil Subjected to Earthquake Loading

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Title:	位於可液化砂土層中離岸風機單樁基礎受震反應的離心模擬;Centrifuge Modeling on the Seismic Response of Mono-Pile Foundations for Offshore Wind Turbines in Liquefiable Sandy Soil Subjected to Earthquake Loading
Authors:	李崇正
Contributors:	土木工程學系
Keywords:	單樁;p-y曲線;風機;液化;離心振動台試驗;研究領域：土木水利工程類
Date:	2011-08-01
Issue Date:	2012-01-17 17:21:50 (UTC+8)
Publisher:	行政院國家科學委員會
Abstract:	目前離岸風力電場的開發主要集中在歐洲地區，台灣目前尚無運轉之離岸風力發電機組。台灣西部海岸雖然風資源豐富，但是屬於地震帶，加上西部屬於疏鬆砂土海灘，地震時發生淺層砂土液化可能性相當的高。而國外目前離岸風力電廠對於地震時，風力發電機組的基礎土壤發生液化對基礎穩定的評估方法尚未深入研究。離岸風機組基礎型式可分為四大類。(1) 樁基礎可分成單樁及三或四樁基礎；(2)重力式基礎是利用混凝土基礎板或其他鋼筒充填砂石料，直接放置於海床；(3)裙狀或筒狀基礎；(4)浮筒式基礎。不同型式的基礎，適合不同裝機容量的風機組及地質條件，初步研究顯示單樁基礎適用於台灣西海岸的地質環境。風機基礎的設計與一般結構基礎的設計主要的差別，在於風機基礎承受很大的彎矩及較小的垂直力作用，這在地震且基礎土壤發生液化時，土壤抵抗側向變形的能力急速降低，將造成風機更為嚴重的水平變位及傾斜。本研究擬利用離心模型震動台進行風機單樁基礎的模型試驗，在與現場持續承受風力作用的類似受力條件下，進行離心模型振動台試驗，探討基礎土壤發生液化時，單樁基礎的地震反應。模型試驗將在風機結構桿件及樁基礎不同位置裝設各種不同的感測器（應變計、加速度計、位移計及孔隙水壓計），藉由樁身的彎矩分布曲線，計算不同液化程度下，諸如垂直土壤反力係數、水平反力係數，了解在不同液化階段基礎土壤抵抗水平力、樁身彎矩及垂直力的變化，提出動態p-y曲線及隨後在不同超額孔隙水壓下，p-y曲線的演化及評估方法，並建立其函數關係。另外試驗成果也可以了解在不同的試驗條件下，樁頭水平變位及樁頭旋轉量的大小，這對處於地震帶的風機單樁基礎的設計應有助益。 Wind power from offshore wind farms has recently been developed very maturely in Northern European country. Although the wind energy resource in western Taiwan is very abundant, the offshore wind power industry has not been developed. The Western Taiwan coastline is classified to a high earthquake activity zone and the sea bed is deposited with very loose sandy soil that is liquefiable during big earthquakes. The current design code of wind turbine foundation does not give the detailed earthquake resistant design requirements for the support foundations in engineering practices. The mono-pile foundation is suitable to the foundation of wind turbine that is located at Western Taiwan. The loading of an offshore wind turbine is different from the foundations of civil structure like traditional building foundations or bridge foundations. The foundations for an offshore wind turbine are subjected to large moments and small vertical loads at seabed level and the foundations are usually subjected to the strong cyclic loading originating from wind and wave loads on the structure. The situation would be more critical if the part of foundation soil becomes liquefied during big earthquakes. A series of centrifuge shaking table model tests will be conducted to simulate the seismic response of a mono-pile with the same loading conditions as those in the in-situ wind farm and the mono-pile is embedded in liquefiable sandy soil subjected to earthquake loading in the three consecutive projects. Sensors (i.e., strain gauges along the pile, accelerometers, LVDTs and pore water pressure transducers) densely instrumented in the mono-pile, superstructure and surrounding soils will provide valuable information for constructing the p-y curves and examining their evolution at various degrees of liquefaction. The difference of seismic response between the civil structure foundations and the wind turbine foundation would be examined and discussed in detailed. The research results from this project will give the design guidelines of the mono-pile for off-shore wind turbines and be greatly beneficial to the wind energy industry. 研究期間：10008 ~ 10107
Relation:	財團法人國家實驗研究院科技政策研究與資訊中心
Appears in Collections:	[Department of Civil Engineering] Research Project

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