先撐管幕工法應用於台灣隧道工程案例探討

Case Study on Application of Tunnel Forepoling Method in Taiwan

郭奇正(C. C. Kuo) ； 劉弘祥(H. S. Liu)

《地工技術》 66期 (1998/04) Pp. 25-36

https://doi.org/10.30140/SG.199804.0002

摘要

台灣位處於板塊碰撞交界處，地層年代及地質構造變異性高。近年來大部份隧道工程均位於地層及構造複雜之西部麓山帶、中央山脈帶及雪山山脈帶，因此隧道洞口必須面臨岩盤強度不足及偏壓問題；而隧道沿線亦經常遭遇斷層、剪裂帶及軟弱地盤問題，為克服此種困難地質，除了加強支撐措施之外，另外必須採取各種輔助工法才能順利通過，其中先撐管幕工法是一種較先進而有效的工法，其原理是在未開挖的隧道頂拱部份預先打入一系列先撐鋼管，並施以固結灌漿，使隧道頂拱預先形成一傘狀保護環，俟隧道開挖後，先撐管幕即與鋼支保、鋼線網及噴凝土形成三度空間支撐系統。本文除了詳細說明先撐管幕工法之施工過程之外，回顧國內施工案例並詳細介紹鐵路新觀音隧道施工實例，敘述先撐管幕工法應用於破碎機開挖隧道的情形，最後依據施工經驗提出檢討與建議，以供隧道工程先進們參考。

關鍵字

洞口 ； 斷層 ； 剪裂帶 ； 軟弱地盤 ； 先撐管幕工法 ； 先撐鋼管 ； 固結灌漿

並列摘要

Taiwan, located at the contact edge of two colliding tectonic plates, is composed of geological formations highly variable in geologic age and geologic structures of high complexity. In recent infrastructure development, many tunnel projects are concentrated within the western foothill and Hsuehshan Range geologic areas both of which are complicated in their geological features. Tunnelling in these areas is inevitably expected to encounter difficulties at two localities: at the portal areas where shallow overburden of friable rock mass is present; and along the alignment, where adverse effects arising from occurrence of faults and numerous shear zones tend to aggravated the situation. To overcome these difficulties, additional measures besides strengthening of the tunnel support have to be adopted to enable smooth execution of the projects. Tunnel forepoling method, among these additional measures, is one of the promising methods which have been implemented in tunnel construction for years in foreign countries. In tunnel forepoling method, a series of steel pipes is installed at the crown of the tunnel ahead of the driving face and then followed with consolidation grouting to form a protection vault or umbrella in the rock mass before excavation. With the subsequent tunnel excavation and support, the forepoled vault combined with the transverse support has, thus, established a 3-dimensional tunnel support system. This article, besides the details of the construction procedures of the forepoling method, is to introduce some tunnel construction projects, one by TBM and the other using backhoe and hydraulic breaker, those through application of tunnel forepoling method. Finally, we submit a discussion and suggestion according to the construction experience to tunnelling engineer for reference.

並列關鍵字

portal areas ； fault ； shear zones ； tunnel forepoling method ； steel pipes ； consolidation grouting