箱涵改道之管幕推进设计施工案例

台北市区铁路地下化南港项目为将既有横交排水箱涵避开新建南港地下车站结构体，并依照现行台北市下水道设施标准以5年1次暴雨频率以改善区域排水，将排水箱涵改道，并于穿越南港路二段采用免开挖的管幕钢管及预筑箱涵节块推进工法，以维护公共管线功能及道路交通服务水平。本工程于南港路两侧设置出发井和到达井，各以40 cm预垒排桩及1~2阶H型钢内支撑系统，穿越南港路箱涵推进段长约22 m，且覆土深约3 m，采用水平打设27支216×8 mm管幕钢管，密排管幕钢管内灌注水泥砂浆，水泥砂浆强度fc’=210 kg/cm2；于出发井管幕内采用推进工法将刃口及22个2.1 m×2.4 m预筑箱涵节块逐步推进至到达井，并于预筑箱涵节块间施作连结及背填灌浆，施作2座人孔。

Design and Construction of Box Culvert by Pipe Roofing and Jacking Method for Underground Railway Project

In the construction of the underground railway in Taipei, an existing drainage culvert should be relocated. The new drainage culvert crosses underneath the existing Nankang RD. Pipe roofing method and precast RC box jacking method are adopted to build the new drainage culvert, so as to ensure the normal operation of the existing utility lines and the ground surface traffics. The length of the mentioned drainage culvert is about 22 m, with about 3 m overburden. A launching shaft is installed on one side of Nankang Rd, while an arriving shaft is installed on the other side of Nankang RD. 27 roof steel pipes (216×8 mm) are installed and cement grout (fc’=210 kg/cm2) is injected into the steel pipes, so as to provide advance support; then 22 precast RC boxes (2.1 m×2.4 m) are jacked from the launching shaft to form the box culvert. At last, the jacked precast RC boxes are connected and backfilling grouting is made. 