The surrounding environment of Dongjing Station of the west extension project of Shanghai Rail Transit Line 12 is extremely complex. The turnback line behind Dongjing Station has a total length of 266.6 meters and successively crosses beneath the elevated bridge piles of Line 9, Jiasong South Road, the No. 7 Bay water pipe lifting area, the Jiasong Landscape River, etc., before finally connecting to the receiving shaft.

To ensure the safety of structures such as the elevated bridge piles of Line 9 during the crossing process, the world's first quasi-rectangular pipe-jacking/shield integrated machine, built by tunnel engineers, came into being.

The quasi-rectangular pipe-jacking/shield integrated machine can complete mode switching in narrow underground spaces to adapt to tunnel boring needs under different environments and working conditions. Among them, the crossover section of the project will be constructed using the quasi-rectangular pipe-jacking method, while the remaining mileage will be constructed using the quasi-rectangular shield method. After the "organic integration" of pipe-jacking construction and shield construction, one machine can serve two purposes, combining the advantages of both methods, breaking through the limitations of applying a single method, greatly reducing project time and economic costs, and providing strong support for tunnel construction.

In the research, development, and manufacturing of the shield, Shanghai Tunnel Engineering Urban Construction Equipment innovatively developed three key technologies for it:

Develop equipment possessing all functions of both pipe-jacking mode and shield mode, and determine the overall layout of the pipe-jacking/shield integrated machine and the conversion process between pipe-jacking and shield modes.

In pipe-jacking mode, the thrust cylinders serve as the force transmission and support system. Therefore, Shanghai Tunnel Engineering Urban Construction Equipment developed a thrust cylinder force transmission monitoring system to monitor the force transmission situation in real time.

After rolling off the production line, the pipe-jacking/shield integrated machine will be put into the construction of the turnback line behind Dongjing Station, making new contributions to the development of Shanghai rail transit construction.