Project name: Beijing Zhangjiakou High speed Railway Tunnel
Constructor: China Railway 14th Bureau
Shield model and diameter: Herrenknecht 12.64m slurry shield
Product used: CONDAT WR89 NG; CONDAT HBW; CONDAT EP2

Project overview:

The total length of Qinghuayuan Tunnel is 6020m (including open cut section and U-shaped groove), of which the shield section is divided into two sections, namely 3 #~2 # and 2 #~1 #. 2 #~1 # section is 2707.5m long, and 3 #~2 # section is 1741m long
2 sets φ 12.64m shield machine tunneling, segment outer diameter 12.2m, inner diameter 11.1m, width 2.0m, shield tail clearance 45mm. The longitudinal section of 3 #~2 # shield tunnel section is downhill at a gradient of 12.9 ‰ after entering the tunnel; The buried depth of the entrance hole is 6.8m, and the buried depth of the exit hole is 19.14m. The exit hole is the lowest point in the section
The longitudinal section of 2 #~1 # shield section is downhill at a gradient of 20 ‰ after entering the tunnel; The buried depth of the tunnel entrance is 21.4m, the buried depth of the tunnel exit is 5.8m, and the buried depth of the lowest point in the section is 28.68m.

Project characteristics and difficulties:

The whole section of the tunnel is composed of silty clay and silty soil with a length of about 750m; The stratum section with silty clay and silt content of 30%~35% is about 1200m long; The rest is pebble soil layer
Relatively speaking, the self stability of silt and silty clay is good, while the self stability of sandy soil and pebble soil is poor, and collapse is easy to occur.
The tunnel also passes through 3 super risk sources and 80 first level risk sources, passes through Metro Line 10 in operation with a clear distance of 5.4 meters, passes through Metro Line 13 on the side with a minimum clear distance of 3.4 meters, and passes over Metro Line 15 with a minimum clear distance of 0.8 meters. The construction organization has many risks, high standards and great difficulties.
In order to ensure the safety management of these high standards, the project uses the CONDAT series of products throughout the project. We also started to focus on following up from the beginning of the project to record the use. The following is the whole process consumption control settlement, which I believe can also provide a reference for more and more large diameter shield construction projects.