On March 27, at the construction site of No. 3 shield launching shaft of the Chongtai Yangtze River Tunnel on the Shanghai-Chongqing-Chengdu High-Speed Railway, the cutterhead of the super-large-diameter high-speed railway shield machine "Linghang" (Pilot), jointly developed by China Railway Tunnel Group and China Railway Engineering Equipment Group, was successfully lifted and lowered into the shaft and successfully mated with the main machine, marking that the shield machine assembly has entered the final sprint stage and laying a solid foundation for launching.

　　At 10:18 a.m., under the coordinated operation of two crawler cranes of 800 tons and 400 tons, the 440-ton shield machine cutterhead was slowly lifted from the ground, completed the turning operation, was accurately transported to the predetermined installation position, achieved precise docking with the shield body, and completed the mating.

　　The "Linghang" shield machine has a total length of 128 meters, a cutterhead excavation diameter of 15.4 meters, and a total weight of about 4,000 tons (including about 2,200 tons for the main machine and about 440 tons for the cutterhead). It consists of the cutterhead, main machine, equipment bridge and four trailers, and is currently the world's largest-diameter high-speed railway slurry balance shield machine. Since the assembly of Trailer No. 1 on February 25, the technical service team of China Railway Engineering Equipment Group and the client's project team have worked together to smoothly complete the welding of the 6+1 cutterhead blocks, as well as the assembly of 1 equipment bridge, 4 trailers and the 10+1 main machine blocks, laying a solid foundation for the mating of the shield main machine and cutterhead.

　　Next, the technical service team will carry out the final assembly of the shield tail and segment erector, and at the same time carry out the connection of various lines of the shield machine, the partial commissioning of each system and the integrated commissioning and testing of the whole machine, so as to ensure the launching milestone.

　　The Chongtai Yangtze River Tunnel is a controlling project of the entire Shanghai-Chongqing-Chengdu High-Speed Railway, connecting Chongming District of Shanghai and Taicang City of Jiangsu Province. The tunnel has a total length of 14.25 kilometers, with a shield section of 13.201 kilometers, including a 1.8755-kilometer onshore shield section and an 11.3255-kilometer underwater section. It is currently a *** high-speed railway river-crossing tunnel project with the world's longest single-head excavation distance (11.325 kilometers), the largest railway tunnel shield diameter (15.4 meters), the highest river-crossing speed (350 kilometers per hour), and the deepest underwater point beneath the Yangtze River (89 meters). After the tunnel is completed, it will for the first time achieve the feat of high-speed trains crossing the river without slowing down.