By rosebell
Being operated by the China Railway 14th Bureau project team, TBM Yangtze River with 12.61m-diameter has broken through on the Chongqing Caiyuanba Yangtze River Railway Tunnel of the Chongqing-Xiamen high-speed railway project and has dug 11.94km.
Including high water pressure, complex geology, as well as buildings in Chongqing, there were multiple challenges during tunneling, as Herrenknecht that supplied the machine said.
The geolog of tunnel’s path involved a mountain comprising karst, a fracture zone, a coal seam gas area, and goaf, and it also crosses the Yuzhong Peninsula and the South Bank area.
Considering that when the tunnel passes beneath the almost 42m-deep main channel of the Yangtze River, it has a minimum overburden of about 10m, and a maximum water pressure of 9 bar, the water penetration along this stretch was also a challenge.
Due to these challenges, TBM was customised with a series of advanced solutions including a high-precision gas-hydraulic pressure balance system, high-pressure scouring system, and high-wear resistant tools. Automatic monitoring of harmful gases and automatic balancing of main drive seal pressure were also successfully introduced.
Reducing the travel time from Chongqing’s Qianjiang River to the main urban area of Chengdu-Chongqing from four hours to less than one hour, the Chongqing-Xiamen high-speed railway’s some sections of the new line are already in operation.
