Photo: Xinhua

A super-large shield tunneling machine rolled off the production line in Zhengzhou, Central China's Henan Province on Tuesday. 

It is the largest-diameter shield machine independently developed by China to date, with an excavation diameter of 16.68 meters, a total length of 125 meters, and a weight of 4,800 tons, CCTV News reported on Tuesday. 

The shield machine was jointly developed by China Railway Tunnel Group, China Railway No 4 Engineering Group, and China Railway Engineering Equipment Group. 

The shield machine adopts a full-face constant-pressure cutter-head, enabling cutter replacement under constant pressure in an eight-bar high-pressure environment, balancing efficient construction with operational safety. 

It is equipped with a circulating slurry discharge system, adopting the industry-leading "screw conveyor direct discharge + out-of-chamber crushing" slurry treatment mode that ensures efficient muck discharge by the slurry pump, and avoids the operational risk of entering the chamber to repair the crusher, building a solid safety defense line for underwater tunnel construction.

The shield machine not only has a large working face but also needs to operate on steep slopes and sharp curves, making the construction environment complex and placing extremely high demands on the equipment's tunneling control precision and posture adjustment capability.

Despite its massive size, the equipment is capable of making small-radius turns because its propulsion system is equipped with hydraulically floating support devices, along with a high-precision guidance system and a segment selection system. Advanced equipment combined with refined control technology together enables the large-diameter shield machine to make agile turns.

China has been developing large shield machines for complex underwater and urban tunnel projects. 

Measuring 13.72 meters in diameter and 145 meters in length, a shield machine, a super-large-diameter slurry balance shield machine, developed by China for high-speed railway projects, rolled off the production line in Hangzhou, East China's Zhejiang Province in August.

Nanjing's first high-speed railway cross-river tunnel has a total length of approximately 20.4 kilometers, of which the tunnel section is about 14 kilometers long, designed as a single-tube, double-track high-speed railway tunnel.

The tunnel runs for an extended distance beneath the Yangtze River bed, with a maximum burial depth of 107 meters and a maximum water pressure of 1.07 megapascals, making it the deepest and highest-pressure railway shield tunnel along the Yangtze River to date.

The cross-river passage will be excavated by two slurry shield machines advancing toward each other from opposite ends, which are scheduled to achieve high-precision docking and on-site disassembly at a depth of 30 meters below the floodplain area on the north bank of the Yangtze River.


Global Times