Design-Build of Invert Concrete Based on Displacement Automatically Measured in Ground With Potential for Heaving:the Hokuriku Shinkansen, the Kaga Tunnel, Northern Lot

摘要

The Hokuriku Shinkansen Kaga Tunnel is a 5,463m-long mountain tunnel (kilometerage 391km937m to 397km400m from origination of Takasaki) and is located on the border between Ishikawa and Fukui Prefectures in the section from Kanazawa to Tsuruga. Throughout almost ground along this tunnel, Neogene Miocene tuff and mudstone were distributed and there was concern about deformation of invert. The results of laboratory testing using ground samples are normally used as decision indexes for squeezing ground but heaving is confirmed in some tunnels after construction and it is necessary to implement measures at the time of construction works including heaving prevention measures which are particularly difficult to implement after the tunnel opens. Therefore, we installed "Invert Displacement Meter®" that automatically measures vertical trackbed displacement through the differential head, depending on the measurements results, we implemented invert deformation measures giving a cross-section with a larger curvature in order to get closer to a circular-shaped invert for sections where large displacement was confirmed.