On the morning of May 22, as the cutterhead slowly rotated, the "Chengdu-Chongqing" shield machine broke through the ground, marking the successful full-length breakthrough of the Shu'an Tunnel, designed by China Railway Eryuan Engineering Group Co., Ltd. This also signifies the breakthrough of the last tunnel on the Chengdu-Chongqing Central Line—China's fastest-operating and highest-standard high-speed railway.
Located in the section between Jianzhou Station and Chengdu Station in Chengdu, the Shu'an Tunnel is not only the longest tunnel on the entire line but also traverses a dense urban building belt in Chengdu, akin to navigating an "underground labyrinth." The Shu'an Tunnel was constructed using a "shield method + cut-and-cover method," with the shield-driven section extending 9,824 meters. Excavation was carried out by two custom-built, super-large diameter earth pressure balance shield machines, "Shu'an" and "Chengdu-Chongqing," with a maximum excavation diameter of 14.5 meters. It is currently the longest-distance and largest-diameter earth pressure balance shield tunnel ever excavated in China.
The project leader for the Chengdu-Chongqing Central Line High-Speed Railway's Pre-station 1 Bid Section from China Railway 11th Bureau Group introduced that the "Chengdu-Chongqing" machine is equipped with a "thrust-segment assembly" parallel construction technology, enabling time-phased jacking in the thrust and assembly zones to achieve simultaneous excavation and segment assembly. It is also equipped with a muck removal system combining a "horizontal continuous belt conveyor + vertical belt conveyor," setting a record for China's largest bandwidth vertical belt conveyor and possessing a muck transport capacity of 1,700 tons per hour.
It is reported that during the construction period, the two shield machines achieved a record daily advance rate of up to 22 meters, with a maximum monthly advance rate of 432 meters and an average of 380 meters, placing them at a leading level globally for shield construction of the same diameter.
The Chengdu-Chongqing Central Line High-Speed Railway is a crucial component of China's "Eight Vertical and Eight Horizontal" high-speed railway network's Yangtze River Corridor. The line starts from Chongqingbei Station in the Chongqing hub, heads west through Chongqing's Liangjiang New Area, Shapingba District, Bishan District, Tongliang District, and Dazu District, then through Ziyang City and Chengdu City in Sichuan Province, and finally connects to Chengdu Station in the Chengdu hub. The main line has a total length of 292 kilometers and a design speed of 350 kilometers per hour.