On September 15, the super-large-diameter slurry balance shield tunneling machine "CREC 1662," jointly developed by China Railway Tunnel Group, China Railway No. 4 Engineering Group, and China Railway Engineering Equipment Group, rolled off the production line in Zhengzhou, Henan Province. With an excavation diameter of 16.68 meters, a total length of 125 meters, and a weight of approximately 4,800 tonnes, the equipment is China's largest-diameter shield tunneling machine independently developed to date, primarily designed for large-section, underwater, and high-water-pressure tunnel engineering construction.
The "CREC 1662" adopts a slurry balance construction mode and is equipped with a atmospheric pressure cutterhead, enabling cutter replacement under atmospheric pressure in an 8 bar high-pressure environment. For super-large-diameter shield tunneling through high-water-pressure strata such as rivers and seas, atmospheric pressure cutter replacement can reduce the frequency of personnel directly entering the high-pressure cutterhead working area, maintaining cutter inspection and maintenance efficiency while lowering high-pressure operational risks.
For the muck discharge system, the equipment adopts a "screw conveyor direct discharge + external chamber crushing" slurry treatment mode. Excavated muck is directly discharged through the screw conveyor and then crushed outside the chamber, which can both improve the continuous muck discharge efficiency of the slurry pump and reduce the need for personnel to enter the slurry chamber to maintain the crushing equipment. This system primarily addresses the issues of large muck volume, high difficulty in handling boulders, and high equipment maintenance risks during super-large-diameter shield tunneling.
From the equipment parameters, the 16.68-meter excavation diameter means that a single tunneling pass can create a super-large-section tunnel space, placing higher demands on cutterhead drive, main bearing load capacity, slurry circulation, attitude control, segment assembly, and overall structural strength. The total length of 125 meters and weight of approximately 4,800 tonnes also make it one of the largest models among domestically produced shield tunneling equipment.
This rollout marks the further development of China's super-large-diameter shield tunneling equipment toward larger sections and higher pressure-bearing capacity. The equipment will subsequently be used for super-large-section tunnel construction and can serve complex underground projects such as river-crossing and sea-crossing traffic tunnels and urban underground passages.