By rosebell
China Railway 1659, a 16.68m-diameter slurry tunnel boring machine (TBM), has completed factory assembly ahead of construction of twin double-deck road tunnels beneath Dongpu Reservoir in Hefei, Anhui Province.
The machine completed assembly on 22 October at a manufacturing facility in Hangzhou, Zhejiang Province. China Railway Group announced the milestone on 30 October.
Jointly developed by China Railway Fourth Engineering Group, China Railway Tunnel Group and China Railway Engineering Equipment Group (CREG), China Railway 1659 will operate alongside China Railway 1662, an identical-diameter TBM that completed assembly in Zhengzhou on 15 September.
The two machines will be deployed on the G4001 North Second Ring Road western extension. The scheme includes an approximately 2.9km shield-driven tunnel section, which represents the main engineering challenge within the wider 3.8km road construction package.
The project involves twin tunnels with a double-deck configuration designed to accommodate traffic in both directions. The wider road scheme will provide eight traffic lanes.
Weighing approximately 4,800 tonnes, China Railway 1659 is designed to generate a thrust force of nearly 30,000 tonnes. It will excavate through challenging geological conditions, including hard rock and fractured ground, while negotiating steep gradients and tight-radius curves.
The alignment also passes close beneath the West Second Ring Road viaduct and the Dongpu Reservoir dam, as well as beneath a protected drinking-water source. These constraints will require careful control of excavation pressures, ground movements and groundwater inflows to safeguard existing infrastructure and the surrounding environment.
The project represents an unusual application of large-diameter shield tunnelling beneath a reservoir used for both flood control and water supply.
Once completed, the North Second Ring Road western extension is expected to improve road connectivity between several western development areas of Hefei, including Canal New City, the High-tech Industrial Development Zone and the Shushan Economic Development Zone.
