On July 8, China's largest-diameter earth pressure balance shield machine, the Shu'an (China Railway No. 1313), was successfully launched at the shield launching shaft of the Shu'an Tunnel on the Chengdu-Chongqing Middle Line project. This marks a push of the accelerator button on the construction progress of the Chengdu-Chongqing Middle Line high-speed railway project, injecting strong momentum into the smooth advancement of this major project.

Launch ceremony for China's largest-diameter earth pressure balance shield machine "Shu'an"

The Chengdu-Chongqing Middle Line Shu'an Tunnel is located in the section between Jianzhou Station and Chengdu Station, with a section length of 10.380 km. The "Shu'an" shield machine will be used in the Tunnel Lot 2 of the Chengdu-Chongqing Middle Line Shu'an Tunnel; the shield-driven section has a total length of approximately 5.265 km and a maximum burial depth of about 43 m. During excavation, the equipment will pass beneath railways and multiple important surface buildings, mainly crossing strata of weakly weathered mudstone intercalated with sandstone, and will face construction challenges such as ultra-long distances, mud cake formation on the cutterhead, water and soil ingress (blowout) in deep-burial strata, and ground settlement control, placing extremely high demands on equipment stability.

China's largest-diameter earth pressure balance shield machine "Shu'an"

Based on the project's geological conditions, China Railway Equipment (CREG) tailor-made the "Shu'an," China's largest-diameter earth pressure shield machine, with an excavation diameter of 14.5 m and a total length of about 122 m. The equipment overcomes multiple key technologies and is designed to solve the challenges of safe and efficient excavation in complex geological environments such as super-large cross-sections and ultra-long distances.

Relying on its outstanding product quality and high-quality technical services, China Railway Equipment (CREG) completed the assembly, commissioning, and split-launch work of the "Shu'an" shield machine in just 25 days, setting a precedent in China for the split launch of the main machine of a super-large-diameter shield machine.

It is reported that the Chengdu-Chongqing Middle Line high-speed railway, as an important railway line connecting Chengdu and Chongqing, is also the high-speed railway project with the fastest target operating speed under construction in the world. The line is designed for a speed of 350 km/h, with conditions reserved for raising the speed to 400 km/h. It is an important support for the CR450 scientific and technological innovation project and an important pilot project for the Smart High-Speed Railway 2.0 construction plan. After completion and opening to traffic, it will further improve the road network structure of the Chengdu-Chongqing region, further shorten travel time between Chengdu and Chongqing, greatly facilitate travel for people along the line, and be of great significance for supporting the construction of the Chengdu-Chongqing Twin-City Economic Circle and forming a new pattern of large-scale development of the western region.