壓重對離岸風機單樁基礎液化行為之影響-離心模型試驗結果

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Title:	壓重對離岸風機單樁基礎液化行為之影響-離心模型試驗結果
Authors:	曾紹倫;Tseng, Shao-Lun
Contributors:	土木工程學系
Keywords:	離岸風機;單樁基礎;土壤液化;離心振動台試驗;offshore wind turbine;mono-pile;soil liquefaction;centrifuge shaking table test
Date:	2020-04-13
Issue Date:	2020-06-05 16:28:41 (UTC+8)
Publisher:	國立中央大學
Abstract:	近年來政府推廣綠色能源建置離岸風場，離岸風力發電機於台灣屬於剛起步階段，有別於其他國家在離岸風機基座的設置上，還需考慮受震後行為及對抗液化的能力，本研究以拋石方式作為研究對象，探討其對液化地盤的影響。主要以探討離岸風機樁基礎於不同厚度之液化砂土層中，受震時，施作拋石範圍大小對樁基礎之影響。在80 g 的離心加速度下，使用積層版試驗箱作為本研究試驗箱，土層上方使用相對密度50%來模擬液化層，下方使用相對密度90%來模擬承載層，並於樁周放置礫石，來模擬現地拋石之情形。試驗結果顯示: 1.於此試驗液化土層20m及30m Hanning wave 1Hz 事件中，放置拋石試驗的上部結構加速度會較無放置拋石試驗出現顯著的放大。2.於本試驗 Hanning wave 1Hz 震動事件中，當拋石範圍愈大，液化土層內的樁身彎矩值會愈大。3.於此試驗Hanning wave 1Hz 震動事件中，上部結構與樁身最大彎矩值呈現高度正相關。得出上部結構出現較大加速度(慣性力)有較大的樁身彎矩值。由於樁身彎矩值會隨著震度加大而變大，遂於設計時，上部結構要抵抗較大震度時，基礎結構能夠承受最大彎矩值也需要做增加。4.於此試驗Hanning wave 1Hz 震動事件中，有拋石試驗孔隙水壓比會較無拋石試驗中的超額孔隙水壓比大。位於液化土層深層的位置，樁周圍之超額孔隙水壓比會大於自由場之超額孔隙水壓比。5.於本試驗液化土層20m及30m試驗中有拋石的情況下，塔架所產生的殘餘位移量會大於無拋石的情況。 ;In recent years, the government of Taiwan has encouraged the construction of green energy and wind farms. Offshore wind turbine technology is at an early stage in Taiwan. At the foundation, offshore wind turbines have some differences compared to other countries, it must take into account earthquakes and liquefaction capacity. In this thesis, the topic of riprap improves the impact of liquefaction on the foundation of the structure. This study focuses on the foundation of the offshore wind turbine at different depths of the liquefaction layer and uses different sizes of riprap range. Using a laminar box in a gravity field eighty times to prepare experiments. The relative density 50% above the soil layer is used to simulate the liquefied layer and the relative density 90% is used to simulate the bearing layer. Then, the gravel is placed around the pile to simulate the riprap on the seabed. Based on the model test results, the following conclusions are made: 1. In 1Hz Hanning wave of 20m and 30m liquefaction layer, com-pared to the acceleration of the upper turbine without riprap, the one with riprap is obviously increased. 2. In 1Hz Hanning wave, when the riprap area is larger, the bending moment of the liquefaction layer will be larger. 3. In 1Hz Hanning wave, the acceleration of upper turbine and the bending moment maximum of pile are highly relevant. For ex-ample, when the acceleration of upper turbine is larger, the bending moment will also be larger. As a result, when the upper turbine needs to resist larger acceleration, the capacity of bending moment maximum for the pile should be increased. 4. In 1Hz Hanning wave, excess pore water pressure ratio of the experiment with riprap is larger than the one without riprap. At the deep liquefaction layer, excess pore water pressure ratio around the pile is larger than in the free-field. 5. In the experiment of 20m and 30m liquefaction layer, the residual displacement caused by tower of the condition with Riprap will be larger than the one without Riprap.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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