On April 9, the A-type prefabricated pipe jacking section of the utility tunnel under the Han-Cai Expressway in the Sino-French Wuhan Ecological Demonstration City successfully completed its breakthrough. The prefabricated pipe jacking section beneath the Han-Cai Expressway is designed with two prefabricated pipe jacking lines, Type A and Type B; this reception marks the successful completion of 50% of the prefabricated pipe jacking section beneath the Han-Cai Expressway.

The utility tunnel project of the Sino-French Wuhan Ecological Demonstration City is located in the Sino-French Wuhan Ecological Demonstration City, Caidian District, Wuhan City, Hubei Province. It is laid out according to the "two horizontal and one vertical" plan (Shengtai Cheng Avenue, Qinrun Avenue, and Zhiyinhu Avenue), forming a "士" shape, with a total trunk line length of about 8.1 kilometers.

The utility tunnel's cross-shaped section has a total length of about 5.7 kilometers. Up to now, the main structure has not yet been completed except for the section beneath the Han-Cai Expressway and the power cable area of Metro Line 4; the main structure of the other sections has basically been completed, and the mechanical and electrical installation works are also being advanced simultaneously. At present, the A-type pipe jacking beneath the Han-Cai Expressway has successfully completed its breakthrough. Next, the pipe jacking machine will be dismantled, relocated, and reinstalled and commissioned. It is expected that the B-type prefabricated pipe jacking construction can begin in early May, the prefabricated pipe jacking section beneath the Han-Cai Expressway can be completed in early June, and the entire utility tunnel can be fully connected by mid-2021.

During the jacking process, the horizontal inclination sensor of the pipe jacking machine is used to monitor the rolling attitude in real time. Through the control of the pre-alarm system and adjustment of the cutterhead rotation speed and direction, deviation of the pipe jacking line can be corrected. Construction is carried out strictly in accordance with the drawings, and the F-type socket-and-spigot waterproofing structure at the joints between pipe segments is carefully implemented to ensure the quality of waterproofing at detailed nodes and reduce leakage defects through quality improvement.

The project chief engineer and deputy project manager of the utility tunnel project stated that the project department will treat joint sealing as a research and development project and plans to jointly develop a new flexible backfill grouting material with Wuhan Construction Research Institute to break through technical difficulties, thereby further reducing or eliminating leakage, ensuring the quality of underground waterproofing works and the functional use of the project, and solving the leakage problems caused by pipe segment joint sealing, foundation settlement, and insufficiently compacted backfill grouting.

The biggest difference between this prefabricated pipe jacking and other prefabricated pipe jacking tunnels is its "square structure" and the large size of the prefabricated components. There is no large prefabricated component factory within 20 kilometers of the Caidian utility tunnel construction area, making transportation inconvenient. The project management department directly adopted on-site prefabrication of pipe segments to solve the problems of large prefabricated component size and inconvenient transportation.

After the utility tunnel of the Sino-French Wuhan Ecological Demonstration City is completed, gas pipelines, water supply and drainage, telecommunications cables, and other pipelines and utility lines will be incorporated into the tunnel. This will solve the problems of "road digging" and overhead "spider webs" caused by the maintenance and capacity expansion of various pipelines, and also avoid repeated excavation during later maintenance, playing a positive role in improving the city's overall image and creating a harmonious urban ecological environment.