扶壁應用於深開挖工程之目的為改善連續壁體之變形，並增加開挖工程之穩定性。本研究探討扶壁增加連續壁抵抗變形之能力以及相關之力學行為，並檢討扶壁之設計方式。在做法上係採用RIDO程式作為分析的基本工具，藉由三個施作扶壁的實際案例，對扶壁之力學行為進行模擬，以驗證本分析方法之可行性，並瞭解扶壁之設置對改善擋土壁體變形行為之效果。另外，本研究假設各種案例，進行不同設計情況之分析，探討扶壁設置深度及數量對連續壁變形行為之影響。 經一系列之分析後得知，扶壁確能明顯減少深開挖工程中連續壁之變形與彎矩，而減少之幅度則視扶壁之長度、深度、數量及地層狀況而定。扶壁設置之數量愈多，則壁體變形與彎矩之減少幅度愈大，但採用適當之扶壁設置間距即可改善壁體之變形，過於密集之扶壁並未能明顯提高設置之效果。且由分析結果亦可得知，扶壁之設置雖可大幅減少連續壁之變形量，但並無法完全解決連續壁之變形問題，適度的支撐仍屬必要。 Diaphragm walls with buttresses are used in deep excavation projects to reduce the wall deformation and to increase the stability of excavation. This research investigated the resistances of wall deformation proposed by the buttresses, and the mechanical behaviors of wall deformation due to different designs are also studied. Computer program named RIDO is used as a basic tool for analyzing the wall deformation. Three case studies of deep excavation were performed to simulate the mechanical behaviors of buttresses, and the feasibility of this analysis method was examined to provide further understandings of the wall deformation with buttresses. Furthermore, different setting methods of buttresses proposed by this research were used to study the influences of embedded depth and number of buttresses. From the analytical results, it is understood that the construction of buttresses will reduce the deformation and moment of diaphragm wall, and the amount of reduction depends on the number, length and depth of the buttresses and the condition of soil layers. The more buttress constructed, the more it reduces the deformation and moment of diaphragm wall. Appropriate number of buttresses may offer significant effects to the deep excavation, but it cannot reduce the deformation of diaphragm walls completely. To avoid the wall deformation, appropriate struts are still necessary for deep excavation.
