連續壁單元分割施工案例檢討

Case Study of Diaphragm Wall Construction

許文和(Wen-Ho Hsu)

指導教授 ： 倪至寬

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2013年)

https://doi.org/10.6841/NTUT.2013.00387

摘要

在深開挖擋土壁的設計多半是設計連續壁外加扶壁或地中壁，但設計者於施工時較難掌握基地扶壁或地中壁單元分割的要素與條件，通常業者都是依照專業施工廠商所建議的方式施工。故本文收集台北盆地及近郊數個工程案例，針對扶壁給予定義、分類。T型單元定義: 扶壁或地中壁與連續壁的混凝土一起澆置，或者扶壁或地中壁的鋼筋與連續壁的鋼筋有搭接，而增加擋土壁的勁度。非T型單元定義: 扶壁或地中壁的混凝土與鋼筋，與連續壁的混凝土與鋼筋分離，不增加擋土壁的勁度。T型單元可分成五種形式，非T 型單元可分成三種型式。並將各型式以圖示將實務上之施工流程、刀法順序來說明，而最後做出優略點比較。
另於各工程處所進行各階段開挖時，連續壁壁體瑕疵的相片採集，將混凝土預估澆置曲線、混凝土實際澆置曲線、連續壁溝槽的超音波檢測結果與逐階開挖後採集相片做比對說明。如此可以加以驗證開挖前與開挖後資訊的真實度，也可分析開挖前施作連續壁時之量測與記錄，依留下的量測與記錄記錄做開挖前之研判，預防開挖時災變產生的可能性，降低鄰損發生的機率。

關鍵字

連續壁 ； 扶壁 ； T型單元 ； 非T型單元 ； 超音波 ； 混凝土澆置曲線

並列摘要

In the retaining wall design for basement excavationi, buttress wall has been adopted along with diaphragm wall. However the diaphragm wall has to be constructed on the base of panel. Two adjacent primary panels are placed leaving out the secondary panel in between. Following the two primary panels, gaps are closed by the secondary panels. Primary panels have smaller width than secondary panels due to the use of end plates. The type of joint between diaphragm wall and buttress wall includes T-shape and non T-shape. There are advantage and disadvantage for each type joint used. In this study, the trench excavation, steel cage construction and concrete placement were recorded for both types of joints from several construction sites. Based on the information collected form these projects, the advantage and disadvantage for each type of joint will be discussed and compared in term of ease of construction, trench wall condition and the ability to minimize the deflection of diaphragm during excation.
During various stages of excavation, the wall defects were observed and were compared with the results of concrete take versus wall depth recorded in concrete placement and trench wall condition recorded from sonic logging. It is verified that the concrete take along with the trench wall condition can be used to estimate the quality condition of diaphragm wall and provide the information about what type of defect in diaphragm wall. Therefore any immediate measures can be taken before basement excavation to prevent any catastrophic foundation failure from happening and to reduce the possible property damage and human life loss.

並列關鍵字

diaphragm wall ； buttress wall ； T-shape joint ； non T-shape joint ； sonic logging ； concrete take versus depth

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