直接土壓力模式應用於側潰影響之樁基波動方程分析

Study on Lateral Spread Affected Piles Using Direct Earth Pressure Model and Wave Equation Analysis

劉凱方(Kai-Feng Liu)

指導教授 ： 張德文

淡江大學/工學院/土木工程學系碩士班/碩士(2009年)

https://doi.org/10.6846/TKU.2009.00324

摘要

本研究係以日本道路協會(JRA)之方法，模擬樁基礎於液化地盤內受側潰流動之動態反應。吾人使用Fortran程式語言開發程式為分析工具，藉Excel試算表程式表示Tokimatsu and Yoshimi 液化潛能評估準則進行地盤液化分析。研究採直接土壓力模式進行波動方程分析，利用有限差分法求解，並使用簡易Bouc-Wen 模式進行樁身剛度值迭代分析，而了解樁基礎於地盤側潰時之變形行為與破壞機制。研究結論如下：（1）針對未液化底層土壤之處理模式，本研究建議以Ishihara土壓力模式將底層土壤之柔度納入分析，進行模擬其土壤非線性行為，以取代傳統完全束制之模擬方式。（2）進行液化潛能評估吾人可得知液化潛能指數與推算液化土層之厚度。液化潛能指數乃JRA法參數之一，對液化土層頂部上方之土層土壓力影響甚大；本研究結果證實液化土層厚度對於樁體反應之影響相當密切。（3）本研究樁頂採固接端，所得結果最大位移量發生於樁頂；於樁頂與液化層底部附近，將發生較大之彎矩值，以上模擬結果可針對地盤受震後土壤發生液化使土層發生流動，對樁基礎頂部變位量與彎矩破壞之影響，亦可考量液化層底部附近將產生彎矩破壞之情形。

關鍵字

液化、土壓力、側潰、樁基礎、波動方程

並列摘要

This study following the methodology suggested by JRA, is to study the single pile dynamic behavior under lateral spreading of soil. It applies the programming language of Fortran to exploit the analysis. Liquefaction potential analysis in this study is Tokimatsu and Yoshimi method, which applies by Microsoft Excel. The research result is essentially founded on the model of wave equation analysis, and the difference equations are used to solve the problem. The stiffness of piles are started iterative analysis by using simplified Bouc-Wen model. This study aims to examine the deformation and destruction of the pile foundation. Three research results are derived in this conclusion: First, this study suggests adopting Ishihara’s theory of lateral earth pressure, in replace of the traditional fixed head, into consideration in order to the flexibility of non-liquefiable and base layer. Second, the data of the liquefaction potential index and the depth of liquefiable layer by calculating can be gathered by Liquefaction potential analysis. The liquefaction potential index is one of the JRA method parameters, and it can influence the earth pressure of the layer which is upon the liquefiable layer very much. The result of this study proves that the depth of liquefiable layer influences the behavior of pile foundation a lot. Third, the head of pile in this study is fixed head. The max displacement of pile occurs on the head of pile foundation. The larger value of the bending moment of pile occurs on the head of pile foundation or near the base of the liquefiable layer. According to the result of this study, the layer liquefies and make the soil flow when the earthquake is happened. The result of this study make us know well that the displacement and the deformation of pile foundation, and can consider that the destruction owing to the bending moment of pile foundation which is near the base of the liquefiable layer.

並列關鍵字

liquefaction, earth pressure, lateral spreading, pile foundation, wave equation

參考文獻

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1. Abdoun, T. and Dobry, R. (2002), “Evaluation of Pile Foundation Response to Lateral Spreading,” Soil Dynamics and Earthquake Engineering, Vol. 22, pp.1051-1058.