Displacement-Based Approach for Assessing Earthquake-Induced Shallow and Deep Slope Failures

Newmark位移評估法為一種常見的邊坡穩定性分析方法，其中降伏加速度為該分析一項非常重要的影響參數，其意義為邊坡在承受多大之地震力條件下邊坡會開始產生滑動，然而邊坡分析中通常無法直接計算降伏加速度而必須經過反覆的疊代運算才能夠得到，使得Newmark位移評估法需花費較多時間與金錢，尤其是針對區域範圍評估更是一巨大花費。為了提升分析之效能，本研究基於圓弧形破壞模式發展了一套簡易方法以評估邊坡受震位移。 本分析方法共分成兩個部分。第一部分為以大量數據建立土層參數與安全係數FS之關係式，同時亦建立不同破壞面幾何與降伏加速度ky之間的關係式。經由本研究發展之關係式即可不需經由疊代運算而直接使用邊坡的土層參數與幾何條件算出降伏加速度。第二部分本研究使用集集地震的地震紀錄回歸製作Newmark位移之預測模型，有別於Newmark假設邊坡為剛性塊體，本研究考量實際上邊坡是屬於柔性塊體，因此使用一維等值線性分析不同自然週期的地層對預測模型參數之影響，進而對剛性位移評估模型進行修正，以應用於受震邊坡之深層與淺層位移破壞之評估。結合第一部分建立之降伏加速度與第二部分建立之位移預測模型即可不需要使用邊坡穩定分析軟體，而只需要試算表進行簡易邊坡受震之位移評估。Newmark's displacement method is a common method for slope stability analysis under seismic loading. Yielding acceleration (ky), defined as a threshold acceleration, is an important parameter for the analysis of slope stability in the Newmark's displacement method. When the earthquake-induced acceleration exceeds the yielding acceleration, the slope begins to slip. Usually, the yield acceleration cannot be calculated directly but be obtained through an iterative analysis. The iterative calculation makes the Newnmak method time-consuming and costly, which results in a huge expense especially for a region-wide assessment. In order to enhance the effectiveness of the Newmark analysis, this study developed a simple method to assess earthquake-induced displacement. This study includes two main parts. The first part is, based on large amounts of data of slope stability analysis, to develop the relationship between the safety factor (FS) and the soil parameters and to define the relationship between the shape of failure and ky. By means of the developed relationships, we could directly calculate FS and ky based on soil parameters and slope geometry. The second part is to develop a prediction model for Newmark's displacement using the data of Chi-Chi earthquake. In reality, the slope is a flexible block but it is assumed as a rigid block in Newmark's method. Therefore, this study uses one-dimensional equivalent linear analysis to account for the influence of flexible slope on the incident motion and access how it modifies the rigid-displacement model. By combining the ky in the first part and the developed model in the second part, it is easily to predict the displacement of earthquake-induced shallow and deep slope failures.摘要 i Abstract ii 目錄 iii 圖目錄 iv 表目錄 vi 符號說明 vii 第一章 緒論 1 1.1 研究背景 1 1.2 研究動機與目的 1 1.3 研究方法及流程 2 1.4 論文內容 5 第二章 文獻回顧與理論背景介紹 6 2.1 邊坡安全係數與降伏加速度ky 6 2.2 安全係數圖表法 8 2.3 Newmark's method 12 2.4 地震位移之預測模型 13 2.5 剛性與柔性邊坡修正 16 第三章 非迭代之Ky估算方法 19 3.1 概述 19 3.2 安全係數FS之估算 19 3.3 滑動面角度α之估算 28 3.4 圓弧形邊坡ky之估算 39 3.5 驗證 45 第四章 柔性邊坡位移量之估算方法 49 4.1 概述 49 4.2 建立剛性塊體之永久位移評估模型 49 4.2.1 位移資料庫之建置 49 4.2.2 位移預測模型 53 4.3 柔性塊體之交互作用之研究 59 4.4 建立柔性塊體之永久位移評估模型 69 4.5 總述 77 第五章 結論與建議 78 5.1 結論 78 5.2 建議 79 參考文獻 81 附錄 8