土石壩受震反應分析

Seismic Response Analyses of Embankment Dam

吳俊賢(Chun-Hsien Wu)

指導教授 ： 倪至寬

國立臺北科技大學/工程學院/土木與防災研究所/博士(2007年)

https://doi.org/10.6841/NTUT.2007.00171

摘要

本研究以有限元素法分析與離心機模型試驗，來探討土石壩的受震行為。首先以文獻回顧來探討反覆載重對土壤性質的影響、剪力破壞時之應力應變行為，然後藉由定義開裂能量Ef與函數B，以modified Oka model來模擬土壤承受反覆載重之勁度衰減特性。引用文獻所述的動/靜態三軸試驗結果以此組成律模式來進行模擬，並與原Oka model及P-Z mark III model之動/靜態三軸試驗的模擬結果相比較，初步評估此組成律模式適合選用為動態分析時之材料組成律模式。
藉由文獻之說明進行控制方程式推導，以釐清數學控制方程式與數值分析程式之對應關係，方便進行數值分析程式LIQCA原始碼的更新與功能改良，並將上述三種組成律模式寫入此程式中。
由VELACS與SEJYT離心機土石壩模型試驗結果與動態有限元素分析結果之比較，可觀察到以下結論：(1)水平加速度從壩底傳遞至壩頂有振幅放大的現象。(2)超額孔隙水壓的激發幅度與本研究定義之初始應力距有正相關。(3) modified Oka model在超額孔隙水壓力之模擬較為合理，P-Z mark III model的加速度模擬較可靠。

關鍵字

土石壩 ； 開裂能量 ； 改良Oka組成律模式 ； 有限元素法 ； 離心機試驗

並列摘要

The aim of the thesis was to study seismic response of embankment dam by finite element method and centrifugal modeling test. First, literatures on soil behavior during cyclic loading and shear failure were reviewed. Secondly, the cracking energy and B-function were defined in the modified Oka model to simulate the soil stiffness degradation under cyclic loading. Thirdly, each numerical simulation of the Oka model, modified Oka model and P-Z mark III model was compared with the results of cyclic/monotonic triaxial testing to assess the property of each constitutive model. The suitability of the modified Oka model to simulate cyclic loading was proved by this assessment.
Furthermore, the controlling formulas were derived from literatures and checked with the numerical source code, LIQCA. Then, based on that, three constitutive models described above were implemented in this numerical code.
Finally, the numerical analysis results of each constitutive model were compared with the centrifugal testing results from VELACS and SEJYT projects. These results led to the following conclusions: (1) the horizontal acceleration from bottom to top of embankment was amplified; (2) the excess pore pressure and the initial stress gap defined in this study were positively correlated; (3) the excess pore pressure predicted in the modified Oka model was more reasonable and the acceleration predicted in the P-Z mark III model was more reliable.

並列關鍵字

embankment dam ； cracking energy ； modified Oka model ； finite element method ； centrifugal modeling test

參考文獻

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