シールドトンネル(7)

[VI-959] Excessive frozen soil thickness control at two brine temperatures.-Construction of U-turn road on the Yokohama Highway Ring Northwest Line-

〇Hiroshi Ogura¹, HIROYUKI IWASAKI², YOSHIHIRO INOUE³, SATOSHI HIRAYAMA¹ (1.SEIKEN CO.,LTD, 2.HAZAMA ANDO CORPORATION Tokyo branch, 3.HAZAMA ANDO CORPORATION)

Keywords:Artificial ground freezing method, Control of frozen soil thickness, Frozen soil, Freezing expansion pressure

In the construction of the High Speed Yokohama Ring Northwest Line Shield Tunnel, the freezing method was adopted as an auxiliary method when constructing a U-turn road.
The construction will connect the two shield tunnels with a rectangular cross section of 7.0m x 10.2m. The mudstone layer occupies 80% of the ground to be frozen, and there is a concern that large freezing expansion pressure will occur. Therefore, at this site, two brine temperatures were created to control the increase in frozen soil thickness during the freeze maintenance period, and excess frozen soil was suppressed while maintaining the safety of the frozen soil.