CNR Shanghai, August 7th (Reporter Yang Jing) The entry line of Shanghai Rail Transit Line 18 from Shenmei Road Station to the working well, which was constructed using the new technology of "New Metro Shield Tunnel Segment Assembly and Connection" for the first time in China, went smoothly. This marks the complete success of the test. This has positive significance for improving the quality of Shanghai rail transit shield tunnels and improving the level of automated construction technology in the domestic rail transit field.

It is reported that in urban rail construction, tunnel segment assembly is the final link of tunnel forming. The quality of segment assembly is directly related to the quality of the tunnel, and has an important impact on the normal operation of the tunnel section.

At present, the domestic rail transit shield tunnel construction generally uses prefabricated lining segments as the bearing structure of the tunnel. Through seam assembly has the advantages of low construction difficulty and high efficiency. However, through seam assembly also has shortcomings, especially in soft soil layers, which are prone to problems such as difficult treatment of tunnel water leakage and tunnel deformation.

It is understood that there are currently 17 rail transit lines in Shanghai, with a total operating mileage of 705 kilometers (including 29 kilometers of maglev lines), and a total of 4 lines under construction, namely Line 10 Phase II, Line 14, and Line 15. and Line 18, with a total mileage of 128 kilometers under construction. Most of these subway tunnels that have been put into operation and are under construction are assembled through joints.

Is there a way of assembling tunnel segments that is more suitable for soft soil layers in Shanghai, instead of the current traditional way of assembling through seams?

In 2017, Shanghai Shentong Metro Group Co., Ltd. took the lead in presiding over the research on the new shield tunnel segment assembly method and new technology, which was implemented by the Shanghai Line 18 Project Company, Shanghai Tunnel Engineering Rail Transit Design Institute, Tongji University, China Railway First Bureau, Shanghai Pudong Concrete Products Co., Ltd. and other units participated in the research.

After researching and innovating and improving the similar foreign segment assembly and connection methods, a "new subway shield tunnel segment assembly connection method" is designed, that is, the segment assembly adopts a plug-type connection in the ring direction and a plug-in connection in the longitudinal direction. It has changed the domestic traditional segment bolt connection method and segment structure.

"This new segment assembly method has high requirements for segment installation accuracy. It must be assembled in place at one time and cannot be disassembled. Therefore, it has higher requirements on the accuracy of shield equipment and the level of shield operation." China Railway First Bureau Shanghai Metro 18 Chen Biao, the person in charge of the Line 5 project, said.

Since this process is applied in China for the first time, in order to ensure the successful assembly, the project department has conducted research and discussions with the owner and the design unit for many times. On the other hand, the construction personnel were carefully selected, experienced shield operators and construction personnel in key positions were selected, and foreign experts were invited to provide technical guidance to deepen the theoretical understanding of the new segment construction technology. In addition, a series of safeguard measures have been formulated to deal with emergencies.