軟弱地盤之深開挖工程中，近年來常以設置扶壁之方式來控制壁體之變位，扶壁對連續壁變位之影響，受到土層與挖撐程序以及扶壁勁度、長度、間距、角隅距離等設置參數之影響，屬於三維之工程問題。 本研究採用三維彈塑性有限元素程式進行分析，以台北基隆河基一區(K1區)之四個深開挖工程監測資料進行回歸分析，取適當土壤參數後，再以二個假設案例進行分析，其中基地面積30M×60M為案例，以改變單一扶壁之位置與長度等參數，來探討角隅及單一扶壁之影響範圍。而基地面積45M×90M為案例，則用來探討多組扶壁之長度、厚度、深度、間距等設置參數，本研究的結果顯示扶壁之厚度大小，對變位量貢獻不大；而扶壁深淺對變位量有影響，但達到一定深度後，其影響貢獻反而不再隨比例增加，而內扶壁之配置間距愈小或長度愈長，都可進一步抑制壁體變位量。此外與TORSA之內扶壁簡化分析法結果比較，發現變位量折減率趨勢相同。且在基一區使用TORSA之簡化分析法中α、β值應分別取為0.25及4。最後本研究提供扶壁之間距、長度與變位折減率之圖表，供使用者在進行設計前，參考本研究之圖表，取得較經濟之內扶壁配置。 In recent years the buttresses has been frequently adopted to control the deformation of diaphragm wall for deep excavation in soft ground. The effect of buttresses on the deformation of diaphragm wall depends upon properties of soil stratum, excavation process, stiffness, length and spacing of buttresses, and distance from corner of diaphragm wall, and it is thus a three-dimensional problem. In this study, we adopted a three-dimensional elasto-plastic finite element model to analyze the deformation of diaphragm with buttresses. Three sets of measured results in K1 region of Taipei basin are used to calibrate the parameters used in the analysis first, followed by varying length and spacing of buttresses to investigate its effect of the deformation of diaphragm by comparing the results of the case without buttress. The length of influence zone of buttresses is approximately the length of buttress, and the deformation of diaphragm wall decreases with increasing length or decreasing spacing of buttresses. The relation among the reduction ratio of deformation, length and spacing of buttresses found in this study can be used to determine the economical layout of buttresses.
