Construction of Shaft Tunnel by Slurry Pipe Jacking through Sedimentary Ground under High Water Pressure

摘要

A shaft tunnel driven by pipe jacking was adopted in order to provide ventilation to the undergroundrnreservoir tunnel under the national highway in Yokohama, Japan. Downward excavation of thern2000mm ID ventilation tunnel starts from ground surface and reaches to the crown of the existingrnreservoir tunnel, which is located 87.8m deep. Depression angle of the tunnel is set as 75.6 degree.rnPore water pressure at the arrival is 0.66MPa. This project is one of the largest in this type of tunnelsrnin Japan. As Oogihara et al. (2003) described on details of the shield machine, this paper focuses onrnequipment and facilities adopted in the project and construction methodology of the inclined pipernjacking.