Recently, the "Xinyue" shield tunneling machine, jointly developed by CRCHI and China Railway 14th Bureau Group, slowly arrived at the Jiangnan receiving shaft, helping the Nanjing Jiangxinzhou Sewage Collection System Phase II Construction Project (Jiajiang River Crossing Section) achieve successful breakthrough.

Breakthrough ceremony

It is understood that the "Xinyue" shield tunneling machine has an excavation diameter of 9.15 meters, a total length of 117 meters, and a total weight of approximately 1,400 tons. The equipment was applied in the Nanjing Jiangxinzhou Sewage Collection System Phase II Project, where the shield tunnel is 693 meters long, with segment outer diameter of 8.8 meters, maximum burial depth of 23.4 meters, and maximum water pressure of 0.34 MPa. Located in the "Jiajiang River Drinking Water Source Protection Zone," the tunnel needed to cross beneath the Jiajiang River as well as the levee, bridge abutments, and municipal pipe networks. The minimum cover thickness at the riverbed was only 10.23 meters, and due to the structural size constraints of the launch shaft, the shield machine had to be launched in split sections, involving numerous and highly difficult construction procedures.

Tunnel breakthrough site

It is reported that domestic shield tunnels currently basically use reinforced concrete segments connected with bolts, with different types of bolts assembling and connecting the segments. However, this project's shield tunnel adopted "new socket-type segments" for the first time, where longitudinal joints of segments use plug-in connectors and circumferential joints use insert-type connectors, placing extremely high demands on the assembly precision of the segment erector.

In response to issues such as shallow cover and soft strata, and the construction of new socket-type segments, the CRCHI R&D team carried out a series of targeted designs for the "Xinyue" to address construction difficulties including high settlement requirements and high precision requirements for segment assembly, ensuring the smooth breakthrough of the project.

Factory acceptance site of the "Xinyue" shield tunneling machine

Since the full launch of the "Xinyue" shield tunneling machine on March 1, 2023, the CRCHI R&D and service teams have remained at their posts, overcome difficulties, and responded promptly to customer needs, providing solid guarantees for the smooth breakthrough of the tunnel project.