加勁土堤受震反應之離心模型試驗;Centrifuge modeling on seismic behavior of reinforced earth embedment

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/53656

Title:	加勁土堤受震反應之離心模型試驗;Centrifuge modeling on seismic behavior of reinforced earth embedment
Authors:	邱益增;Ciou,Yi-zeng
Contributors:	土木工程研究所
Keywords:	顯著頻率;振動台試驗;加勁土堤離心;centrifuge shaking table test;predominant frequency;reinforced earth embedment
Date:	2012-08-14
Issue Date:	2012-09-11 18:05:06 (UTC+8)
Publisher:	國立中央大學
Abstract:	加勁擋土結構在1980年代後期引進台灣，自此加勁材料及各式加勁結構蓬勃發展。台灣屬於地震頻繁地區，結構物設計須考慮地震作用下之安全性，若要將耐震性能設計觀念應用於土堤耐震設計，則有必要掌握土堤結構在不同等級地震作用下之變形性，以及影響其動態行為的相關參數。本研究利用離心模型試驗研究加勁土堤動態反應，改變不同加勁材強度、加勁材長度及加勁間距，變化土堤坡度及高度，探討不同幾何條件與加勁材料配置下，在不同強度振動力作用下，加勁土堤加速度與變形性之差異。研究結果顯示：(1)模擬現地4m高的加勁土堤試驗結果顯示土堤顯著頻率在10Hz左右，8m高的加勁土堤試驗中，土堤顯著頻率約在5.7Hz，改變加勁間距、加勁長度及土堤坡度對土堤顯著頻率影響不大。模擬現地12m高加勁土堤的試驗顯著頻率為4.5Hz，顯示加勁土堤顯著頻率與高度有明確的相關性。(2)少數1Hz振動事件中的加速度變化會呈現縮小反應，縮小反應與土堤大量變形有關。(3)8m高的加勁土堤試驗中，加勁材強度112kN/m及62.5kN/m的試驗結果顯示加勁土堤耐震性能均十分良好。(4)由8m高加勁土堤內部斷裂破壞連線可知，斷裂位置與坡面水平距離最遠的加勁材大多位於土堤頂部，破壞面類似圓弧破壞。(5)由試驗後破壞土堤回收的加勁材可知，土堤底部往上約0.2~.03H的加勁材伸長量最大。A series of centrifuge model tests was conducted to simulate the dynamic response of reinforced earth embedment. The variables considered in the centrifuge testing program were the reinforcement tensile strength, reinforcement spacing, reinforcement length, embedment height, and slope inclination. The main objectives were to investigate reinforced earth embedment in different reinforced type, and geometry. According to model test results, the following conclusions are made：(1) For a 4m-high embedment, the predominant frequency is about 10Hz, for an 8m-high embedment, the predominant frequency is about 5.7Hz, and for a 12m-high embedment, the predominant frequency is about 4.5Hz, which means predominant frequency had a significant association with the height of embedment. (2)There are some acceleration attenuation phenomenon occurs at 1Hz event and related to the significant movement of the embedment. (3)For all 8m-high embedment, model conducted with the reinforcement tensile strength 112kN/m and 62.5kN/m performed very well under seismic loading.(4) According to the rupture point of reinforcement we can draw a failure surface, the failure surface it similar to a circular failure surface.
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