潜盾隧道穿越台、高铁下方挡土壁之案例探讨

台北捷运新庄线于松江南京站与忠孝新生站之间，其潜盾隧道工程必须自营运中的台铁与即将营运高铁隧道结构下方通过，且需穿越既有地铁结构下方之六道挡土壁体，包括不规则之连续壁体及非连续性之基桩群等。本项工程由于基地外部环境条件诸多限制，捷运隧道线形与穿越之壁体及基桩群又非正交，壁体无法维持一般完整性与连续性之需求，造成穿越过程中莫大之困扰与风险。本施工案例采取之工法系由潜盾机盾首进行挡土壁体前后之水平灌浆地盘改良，并配合出舱挖掘作业以玻璃纤维喷凝土工法及点井工法搭配使用，以确保挡土壁体敲除作业之安全，敲除过程藉由仅约85cm×55cm之进出通道，进入潜盾机前方狭隘的工作区间内，以人工敲除方式排除障碍。特就穿越前述地下障碍所实行对策与施工方法，以及穿越过程所面临困难、危险状况之发生、因应与克服，做深入之案例探讨。

The Discussion for Bored Tunneling Driving Through the Retaining Wall Beneath the Existent Subway System

Bored tunneling of the project between the Songjiang Nanjiang station and Zhongxiao Xinsheng station in the Xinzhuang line of Taipei MRT was challenged by the conditions of driving through the underground structure of six panels of the retaining wall ,including the irregular continuous walls and non continuous base of foundation piles, beneath the existent tunnels of the Taiwan Railway （TR）and the Taiwan High Speed Rail （THSR）system. As result of the limitation by the external environment condition, non orthogonal between the tunnel alignment and the retaining wall or base of foundation piles. For the safety reason, the construction procedure of this case adopted by the horizontal grouting to improve the soil condition around the domain of the retaining wall from the top head of the TBM, and coordinates with the glass fiber shotcrete method and the well point method to excavate and break up the obstacles and wall bodies through the air chamber and an only approximately 85×55 cm channel enter a very narrow working space at the front of TBM. This article aims at the construction method and countermeasure adopted by this case, as well as the difficulty during the TBM driving through period, furthermore, the widely discussion of the dangerous condition occurrence, countermeasure and overcomes.