China’s largest domestic TBM ready for Hefei reservoir drive

A 16.68m diameter slurry TBM has completed factory acceptance ahead of a 2.9km drive beneath Dongpu Reservoir in Hefei, China. Named China Railway 1662, the machine completed factory acceptance in Zhengzhou on September 15 and will be deployed on Lot 1 of the Hefei G4001 Link, also known as the North Second Ring Road West Extension. The TBM was developed and manufactured by China Railway Engineering Equipment Group (CREG) in collaboration with Lot 1 contractors China Railway Tunnel Group and China Railway No.4 Engineering Group. The RMB3.17bn (US$445m) Lot 1 contract has a construction period of 1,460 days. The wider North Second Ring Road West Extension crosses Hefei’s Shushan and Luyang districts and extends approximately 10.6km from the North Second Ring interchange to the Bailianyan Road expressway interchange. Lot 1 runs approximately 3.8km from the West Second Ring Road/Qingxi Road interchange to Kexuedao Road and will provide eight traffic lanes. Its principal tunnelling element is a 2.9km shield-bored crossing beneath Dongpu Reservoir, constructed as twin, double-deck tubes. The reservoir provides both flood-control and drinking-water functions, making the crossing an unusually sensitive application for a super-large diameter TBM. China Railway 1662 has an excavation diameter of 16.68m, an overall length of 125m and weighs approximately 4,800t. Its accessible cutterhead system is designed to allow cutter replacement at atmospheric pressure with chamber pressures of up to 8bar, avoiding the need for hyperbaric cutter interventions. The alignment presents a series of demanding tunnelling conditions, with the TBM required to pass close to the West Second Ring elevated highway and the reservoir dam, as well as beneath a protected drinking-water area. The machine also has to negotiate steep gradients and tight-radius curves. Its thrust system incorporates hydraulic floating supports, together with high-precision guidance and segment-selection systems designed to maintain alignment and reduce loading on the thrust cylinders and segments when negotiating curves down to approximately 600m radius. The TBM is fitted with a 38% opening-ratio accessible composite cutterhead and a dedicated muck-removal system. Excavated material is discharged by screw conveyor before being crushed outside the excavation chamber, allowing crusher maintenance to be carried out without personnel entering the pressurised chamber. Construction of the reservoir crossing is already under way, with excavation of the TBM launch shaft and construction of the working-shaft base slab previously completed. The project is one of a relatively small number in China to combine a super-large diameter shield-bored crossing beneath a major water-supply reservoir with a twin-tube, double-deck highway tunnel configuration. CREG CREG (China Railway Engineering Equipment Group Co., Ltd.) is a worldwide underground solutions provider for a full range of mechanized... More Information | [email protected] | +86 371 6060 8680 Comments: