本研究之目的為利用三向度有限元素分析不同扶壁處理方法對連續壁壁體變形的影響。首先針對不同扶壁拆除時機進行一連串的參數研究，研究成果顯示，若扶壁隨開挖逐階段拆除扶壁，其抑制變形成效有限。若開挖至最後開挖面再敲除開挖面以上扶壁，則扶壁可發揮較多摩擦力以減少大量壁體變形。若開挖至最後開挖面後再建造筏式基礎及地樑系統並拆除開挖面以上扶壁，此扶壁拆除方法可減少近一半的無扶壁之連續壁變形，但此方法在實際施工上有介面衝突等複雜問題。若開挖至最後開挖面後再鋪設劣質混凝土並拆除開挖面以上的扶壁，此扶壁拆除方法所抑制連續壁變形成效不遜於前述之各扶壁處理方法，且沒有施工複雜等問題，並針對此扶壁拆除工法進行特性研究。
若在連續壁變形之反曲點以上設置相同高度的扶壁，則可大幅減少壁體變形，且大於反曲點高度的扶壁對抑制變形的成效差異不大。扶壁貫入深度所影響為最終開挖面以下的壁體變形，對抑制整體連續壁變形效益不大。
在本研究中，開挖至最後開挖面後再鋪設劣質混凝土並拆除開挖面以上的扶壁之方法，其使用較短之扶壁高度和貫入深度，即能有極佳的抑制變形成效。

The purpose of this study is to study the effect of different buttress treatment on the wall deflection by using the three-dimensional finite element method. First, a series of parametric studies were conducted for different timing of buttress wall removal. The results show that if the buttress wall is demolished along with the excavation stage, the reduction of the wall deflection is limited. When the excavation reaches to the final excavation surface and the buttress wall above the excavation surface is demolished, it would provide more friction and stiffness to reduce the wall deflection. On the other hand, if the buttress wall is demolished after constructing the raft foundation and ground beam system, then it can reduce the wall deflection two times smaller than those without the buttress wall. However, this method might be difficult to implement in real construction because the buttress wall would affect the construction of the raft foundation and ground beam system.
Therefore, if the buttress wall is demolished after adding the poor concrete below the final excavation surface, then the wall deflection is close to those directly constructing raft foundation and ground beam systems. Meanwhile, this method has no problem in the implementation in real construction. If the buttress wall height is equal to the inflection point of the wall deflection, then the wall deflection can be reduced significantly. However, the buttress wall greater than the height of the inflection point has little effect in reducing the wall deflection. The results also show that the penetration depth of the buttress wall has little effect in reducing the wall deflection. In this study, the method of laying poor concrete and removing the buttress wall above the final excavation surface using shorter buttress wall height and penetration depth than those without the buttress wall, it can provide good performance in terms of reducing the wall deflection and ground settlement.

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