Hengyang Second Ring Road Hejiangtou Xiangjiang Tunnel
Release time:
2025-12-24
Abstract
Construction unit: China Construction First Bureau Group Co., Ltd.
Device Number: ("China Construction Pioneer" Tunnel Boring Machine) China Railway Construction Heavy Industry
Cutting disc diameter: 11.65 meters
Tunneling length: 935 meters
Project Features:
The longitudinal gradient design presents a level of difficulty rarely seen nationwide. With a tunnel gradient reaching 5.0%, this is China’s largest “V-shaped” longitudinal-gradient, large-section slurry shield tunnel crossing the river. Such an extreme gradient poses extraordinarily high technical challenges for shield launching, and makes it particularly difficult to adjust the shield’s attitude during excavation—especially during the “upward” driving phase, where precise control of parameters is crucial. The geological conditions are exceptionally complex: the tunnel is located at the confluence of three major rivers—the Xiangjiang, Leishui, and Zhengshui—and must pass through unfavorable geological formations including karst regions, fractured zones, and strata that are soft above and hard below. Moreover, the tunnel faces the challenge of groundwater corrosivity. Additionally, the launch shaft is situated close to the eastern embankment of the Xiangjiang River, raising the risk of river water seeping into the excavation pit and compromising structural stability. The core technologies employed here are internationally leading; notably, the innovative use of silane impregnation technology for corrosion protection of tunnel segments—a technique commonly used in port engineering—is being applied for the first time to underground tunnel corrosion protection. Furthermore, the newly developed “grouting and compaction method for replacing low-density fill materials in riverbed cavities” has also reached an internationally advanced level.
Year of commencement: February 2017
Year of completion: May 2018
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