台北市忠孝橋托底工程案例介紹

Underpinning for Pier A15 of Chunghsiao Bridge of Taipei

蘇信淵(S. Y. Su) ； 彭嚴儒(Y. J. Peng) ； 朱旭(H. Ju) ； 陳鴻濤(H. T. Chen)

《地工技術》 53期 (1996/02) Pp. 55-64

https://doi.org/10.30140/SG.199602.0006

摘要

台北市忠孝橋橋墩A15的基礎原係由16支直徑0.5公尺、長度35公尺之鋼管樁支撐，由於捷運隧道路線通過該橋墩下方，必須於潛盾隧道通過前對橋墩先進行托底工程及切除北側之6支鋼管樁。托底作業期間橋墩之容許沉陷量為10公厘。主要工程項目包括設置直徑1.2公尺、長度50公尺之基樁5支及深2公尺、寬1.5公尺之支承梁。並於新設之托底支承梁之樁及帽梁施作時，開挖深約8公尺。橋墩荷重轉移作業期間採用自動監測系統即時監控轉移過程。監測項目計有基樁、帽梁、千斤頂及橋墩之位移量，千斤頂荷重及以鋼筋計監測基樁荷重。觀測結果顯示轉移期間千斤頂最大總荷重達483噸，最大衝程約3公厘，基樁最大沉陷約0.2公厘。整個荷重轉移過程中，橋墩隆起約1.5公厘。而捷運南港線下行線潛盾通過期間，橋墩僅產生約1公厘之沉陷。

關鍵字

托底 ； 地盤改良 ； 荷種轉移

並列摘要

Pier A15 of Chunghsiao Bridge is founded on 16 steel pipe piles with a diameter of 500mm. Six of them blocked the way of two stacked tunnels of the Taipei Rapid Transit Systems and had to be removed before the shield machine passed under the pier. The bridge structure is a continuous prestressed beam. The settlement of the pier was limited to 10mm. A pit was made first to expose the pile cap and to provide sufficient headroom for subsequent operations. Five cast-in-place concrete bored piles were installed and cast into a load-transfer slab. The load from the bridge was transferred to these new piles by jacking the pile cap against this transfer slab before the cutting of the old piles. A total jacking force of 483 tones was applied. After all these six piles were cut, the transfer slab was structurally connected to the pile cap to form a composite cap and the operation was then completed. Instrument readings indicate that the pier heaved up by an insignificant amount of 1.5mm during underpinning. The settlements of new piles were only 0.2mm. The lower tunnel has been completed and the settlement of the pier during the passing of the shield machine was only 1mm.

並列關鍵字

underpinning ； soil improvement ； load transfer