工程線上 Status Report 信義線潛盾鏡面連續壁 玻璃纖維補強筋取代鋼筋

為降低施工風險，捷運信義線安和路以東之工區，在潛盾機進出連續壁鏡面處採用GFRP玻璃纖維補強筋（Glass Fiber Reinforced Polymer）取代鋼筋，由於潛盾機可直接進出連續壁鏡面，而大幅縮短破鏡時間及減少破碎振動，避免擋土結構破壞，導致土壤側向解壓滲水造成土壤流失之情況發生，因此提高了工程安全性。該工區有19單元處潛盾連續壁鏡面，其中有15單元採用GFRP，均已施工完成。

　

潛盾隧道傳統施工法因潛盾機無法鑽除連續壁鋼筋，於發進及到達時為使潛盾機得以穿越連續壁鏡面，須以人工或機械打除，不但產生噪音及空氣污濁，且在過程中因僅依賴土壤改良體的自立穩定，若稍有不慎，極易造成土壤崩塌下陷，導致已完成之隧道環片崩落，或鄰房產生傾斜、倒塌等狀況。

　

潛盾機進出連續壁鏡面處鋼筋改採GFRP，乃運用其高硬度但屬脆性材料特性，並配合調整潛盾機刃齒，使潛盾機可直接進出連續壁鏡面，解決潛盾機無法切削鋼筋的問題，加上其為高強度材料，亦能符合使擋土壁斷面穩定之勁度要求，除可改善傳統鏡面的破除方式缺點，更可提高施工之安全性。本工區所採用的GFRP在國外已超過300個破鏡成功案例。

　

傳統鋼筋鏡面破鏡

　

GFRP為棒狀，根據ACI Code（美國混凝土協會規範）規定計算配筋量，材料均需在工廠定尺完成，尤其是剪力筋等為彎鉤材料，訂料時就需決定尺寸，工地僅能裁切無法彎曲加工，而且GFRP筋無法以電焊固結，須以綁紮固定，且搭接於上、下部鋼筋籠之搭接區域須採用U型螺栓固結，吊放入槽溝時則另須拆除GFRP鐵材工作架，因此施工時間需3~4天，較一般鋼筋籠時間長。

　

GFRP筋鏡面破鏡
　

　

Polymer Replaces Steel Ends of Concrete Diaphragm Walls

During traditional mirror-face excavation operations, a steel structure at the end of a concrete diaphragm wall needs to be broken through by manual labor or mechanical means instead of the shield tunneling machines in a highly risky process. During the construction of the Xinyi line, glass fiber reinforced polymer (GFRP) was used to replace the steel structures. GFRP is applied on both ends of diaphragm walls where shield tunneling machines perform mirror-face excavation so as to lower the possibility of tunnel leaks or damage occurring to the excavator while solving the problem arising from the shield tunneling machines being unable to break through the steel structure.

In addition, GFRP is strong enough to meet the demands of maintaining the retaining wall section integrity. The replacement not only improves the traditional break-through process but also enhances construction safety. Thus far, there are more than 300 examples of successful application of GFRP worldwide.


　

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