近年來加勁擋土結構物受到廣泛使用，具有施工快速、低造價與耐震性佳等 優點，已逐漸取代傳統重力式擋土牆。經由多年來完工案例的驗證下，傳統加勁 設計方法未經修正而顯得過於保守，詳細了解其力學機制與受震反應有助於使設 計方法更為精進，因此本研究以數值方法詳細探討加勁土堤靜、動態之力學行為， 並進行參數分析以了解影響加勁土堤受震行為之要素。 本研究以二維有限差分法分析程式FLAC2D（Fast Lagrangian Analysis of Continua）建立數值分析模型，探討土壤元素組成律與分層堆疊於加勁土堤靜態 分析時之差異，進而考慮不同加勁材料之應力應變行為，加勁材料嵌固模式與滑 動模式對動態行為之影響，以釐清各項因素影響程度之大小。本研究以FLAC2D 內建之Fish 語言建立自動建模之模組，可考慮不同加勁土堤參數，包含坡度、 高度、加勁間距與長度等因素，快速建立數值分析模型進行動態分析，得到各項 參數分析之結果，以進行數據分析與比較，進而歸納結果。動態分析時考慮4 筆不同地震規模之加速度歷時，調整最大加速度值進行分析，探討加勁土堤受震 過程之變形行為，以了解土堤受震之變形機制。 傳統加勁路堤之設計方法均以極限平衡法為基礎，本研究以極限平衡分析法 計算加勁土堤圓弧破壞模式與雙楔形破壞模式之降伏加速度，以Newmark 滑動 塊體法計算加勁土堤之永久位移，與本研究有限差分之分析結果進行比較，最終 將分析之永久位移建立經驗關係式，提供簡易計算之用。 研究結果顯示，加勁材料嵌固模式與滑動模式對土堤之變形影響不大，僅影 響加勁材料之軸力分布，動態分析過程顯示，加勁土堤之變形屬於漸進式破壞， 其潛在破壞面隨著不同受震程度而有所不同，與極限平衡法存在很大的差異，其 受震變形等級受到許多因素影響，為極限平衡法無法模擬的部分，突顯數值分析 模型在加勁路堤耐震性能設計之重要性。;It’s important to understand the deformation mechanism of reinforced embankment during seismic excitation. At the first, this study used FLAC2D to investigate the influences of filling process and constitutive relations on the results of pre-earthquake static analysis. Furthermore, the effects of slip conditions of the interface between soil and reinforced material, and the stress-strain relation of reinforced material are also explored. The auto-mesh program has been developed using Fish subroutine of FLA2D for performing the sensitivity study of different parameters on the dynamic results. The investigated parameters included the slope angle and height, the length and spacing of the reinforced material. Based on the dynamic analysis, the progressive deformation and failure process are clearly observed and recorded. The traditional design of reinforced embankment is based on the limit equilibrium method (LEM). This study used LEM to calculate the yield acceleration of the reinforced embankment by assuming the circular and two-wedge failure surfaces. The permanent deformation is then computed by Newmark sliding block method (NSBM). It is found that the permanent deformation calculated by FLAC2D is significantly larger than that based on LEM and NBSM. Therefore, a more accurate simplified method was established for estimating the permanent deformation of reinforced embankment which is based on the analyzed results from FLAC2D.
