潛盾隧道鋼筋混凝土環片循環載荷試驗與分析

有鑑於都會區大眾地下運輸系統、地下電力管道及衛生下水道主幹線工程等，近年來大多規劃採潛盾工法施工，並普遍使用預鑄之鋼筋混凝土環片支承，以穩定開挖面。鋼筋混凝土環片設計一般皆由以往之經驗傳承，環片鋼筋用量之設計是否恰當，須仰賴在環片製造時裝設監測儀器。藉由環片內之監測系統記錄環片製造、環片工地組立、背填灌漿及營運階段的計策結果回饋設計，以提昇設計之品質。此外，由於都會區內施工用地取得困難，隧道線型設計採上下堆疊方式已屢見不鮮，或近接施工所產生之互制影響，也可於施工期間藉由環片監測提供設計參考。環片內監測儀器以往曾採用光纖感測器作為應變之量測工具，但由於其價格較高，故傳統監測儀器預置在環片之預鑄過程，其表現行為頗具探索價值。本研究係藉由環片試體內裝設鋼筋計，以了解環片製造過程中，混凝土水化作用對環片溫度、鋼筋應變變化情形及透過環片循環載重試驗過程，了解鋼筋應力及應變變化情形，再利用結構及鋼筋混凝土力學理論分析結果與實測結果進行比對，進而深入了解傳統監測儀器預置於鋼筋混凝土環片內之適用情形，在研究過程中發現了鋼筋計在鋼筋混凝土環片監測中，具有良好之適用性。

關鍵字

混凝土環片；循環載荷試驗；振弦式鋼筋計

並列摘要

This study is used to verify the suitability of conventional rebar strain meter to monitor the behaviour of shield segment. Four vibrating wire rebar strain meters and thermistors are installed in a steel cage of test segment before concrete placement, steam and water curing. Both temperature and strain of rebar are recorded through out the manufacturing process. The results indicate that the variation of rebar strain is consistent with the temperature. Then, this test segment is tested by cyclic two points loading, in which the strains of rebar and deflections at center point on both sides of test segment are also monitored. The samples of rebar and concrete cylinder are tested in lab to produce the stress-strain relations, respectively. The comparison of moments and deflections of segment during cyclic loading between analytical solutions and measured results are presented in this paper. The results indicate that the conventional rebar strain meters are not only intact after extreme curing processes but also functioning well during cyclic loading.

並列關鍵字

Precast Reinforced Concrete Segment ； Cyclic Loading ； Vibrating Wire Rebar Strain Meter

參考文獻

[15]Wen-Chieh Cheng, James C. Ni, Feasibility study of applying SOFO optical fiber sensor to segment of shield tunnel.Tunnelling and Underground Space Technology, (2009).24(3) ,pp.331-349.

[16]Gilbert R.I., “Tension Stiffening in Lightly Reinforced Concrete Slabs”, Australian Journal of Structural Engineering, Institution of Engineers Australia, Vol 8 No 3, 2008, pp 189-196.

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