On September 12, the Nanjing Metro Line 11 project completed the rectangular pipe jacking machine construction for ancillary Entrance 10, marking the breakthrough of Entrance 10 of Pukou Wanhuiting Station into the main station structure.

Pukou Wanhuiting Station of Nanjing Metro Line 11 is located on the south side of the intersection of Pubin Road and Pukou Avenue, and ancillary Entrance 10 is located on the east side of the station, with the entrance passage running across Pubin Road. Once completed, pedestrians will be able to use this passage from Kangping Road under Pubin Road to Pukou Wanhuiting Station to transfer to Line 10.

The Entrance 10 pedestrian underpass at Pukou Wanhuiting Station crosses the Pubin Road expressway, where traffic is heavy and the surrounding environment is complex, making open-cut construction unfeasible. Therefore, the rectangular pipe jacking method was adopted, with a 5×7 m extra-large cross-section earth pressure balance pipe jacking machine advancing from Entrance 10 toward the station.

The pipe jacking passage lies in water-rich mucky silty clay with only 5.1 m of cover, and the geological and hydrological conditions are complex, making advancement difficult. Before launching, the project department anticipated the adverse geological and water level conditions by adding emergency dewatering, reinforcing the portal, and increasing the frequency of monitoring and measurement. Combined with analysis and summary of monitoring data, the stability of the excavated face soil was maintained by controlling the front earth chamber pressure and the volume of excavated material. In addition, construction parameters were continuously optimized based on jacking thrust and monitoring data during advancement, and subsequent construction parameters as well as grouting and mud injection measures were adjusted in a timely manner to further control deformation of the surrounding environment and ensure smooth pipe jacking.

Since preparations for pipe jacking construction began, the Nanjing Metro Line 11 project team has carried out scientific planning and meticulous deployment for the early-stage site layout and the investigation and demonstration of equipment selection for pipe jacking construction, and organized experts to demonstrate and improve the special construction plan for the safe tunneling of the pipe jacking machine and the plan for large equipment lifting operations. At the same time, in response to thorny issues such as the high difficulty, high requirements, tight schedule, and heavy tasks of pipe jacking construction, technical briefings were conducted at all levels and work instructions were prepared.

By fully staffing strong technical teams and construction crews with rich experience and strong execution, the project team successfully overcame a series of unfavorable factors, including the lifting and transport of extra-large components, a narrow construction site, cross-operation at the site, and a tight construction schedule. They promptly coordinated and resolved various problems arising at the construction site, ensuring that the disassembly, lifting-in, transfer, lowering into the shaft, assembly, and commissioning of the pipe jacking machine, as well as other supporting facilities, were efficiently completed within the established time, ultimately achieving smooth breakthrough and reception as planned.

After 26 days of continuous jacking, the project's rectangular pipe jacking machine construction was successfully completed, laying a solid foundation for the early completion of the project's ancillary works and subsequent work, and fully demonstrating the company's new advantages in the field of trenchless technology for underground engineering. At present, the project has entered the comprehensive sprint stage, and the project department will maintain its momentum and uphold the determination to overcome difficulties and fight to win, ensuring high-quality project delivery.