On August 30, 2024, as the shield machine's cutterhead broke through the wall, the right-line tunnel of the shield-driven section from Hechuan Road Station to Hanchuan Road Station (hereinafter referred to as the "He-Han Section") of the second phase of Qingdao Metro Line 2 was completed. This is the work area of the second phase of Qingdao Metro Line 2 that **successfully completed shield construction across the entire line, and also the work area of the third phase of Qingdao Metro that **successfully concluded the shield construction process.

The double-line He-Han Section has a total length of 1,135.1 meters. The construction team deployed two shield machines simultaneously for excavation of the left and right lines. The "Liu Shuai" and "Qi Jie" shield machines both launched from Hechuan Road Station, bored eastward, and were received at Hanchuan Road Station.

Up to now, the main structure construction of Hechuan Road Station and Fo'erya Station of the second phase of Qingdao Metro Line 2 has been completed. The section from Fo'erya Station to Hechuan Road Station (the "Fo-He Section") and the section from Hechuan Road Station to Hanchuan Road Station (the "He-Han Section") have both achieved double-line breakthrough, consistently maintaining a "bellwether" position across the entire line. Since entering the site, the project has closely centered on the target requirements of safety, quality, schedule, and management, meticulously planned construction organization, scientifically coordinated resource allocation, and infused refined management into every aspect of construction. It has successively achieved important project milestones such as the **opening of the traffic diversion road, the **start of enclosure structure construction, and the **completion of excavation condition acceptance.

The He-Han Section features dense buildings, hard rock, and strong geological karst development. The shield tunnel has a total length of 567.55 meters. During construction, the project faced the problem of frequently crossing soft-over-hard strata over long distances. The section tunnel lies beneath roads with densely distributed surrounding pipelines, imposing stricter requirements on surface settlement control. Construction also had to overcome difficulties such as work stoppages during the high school and college entrance examinations. Heavy-duty disc cutters with strong rock-breaking capability were selected to solve the cutterhead "mud cake" problem, and technical challenges such as difficulty in maintaining pressure at the tunnel face and failure of segment sealing and waterproofing also had to be overcome.

During shield tunneling, one technical staff member was assigned inside the tunnel to monitor segment assembly and grouting on site, consolidating routine process management. For the quality of formed segments, the 10-ring挂牌 inspection and acceptance system by quality inspectors was strictly implemented. In addition, the project team carried out strict monitoring, re-measuring the axis of the formed tunnel once every 10 rings, with a 5-ring overlap required between successive re-measurements, so as to adjust the tunneling attitude and grouting parameters in a timely manner. Testing work also systematically carried out comparative selection of synchronous grouting mix proportions, with slurry quality sampled and tested every 5 rings to dynamically track parameters such as pumpability and consistency, ensuring project quality.

In response to the construction difficulties of the section, the shield machine was equipped with multiple intelligent innovative technologies—a newly added advanced geological prediction system to effectively detect adverse geology, achieve early detection and early warning, and fully guarantee safety during tunneling; in response to complex and variable stratum geology, the shield machine was also equipped with three intelligent systems including a new-type grout stop plate, a shield gap measurement system with accuracy of less than 5 millimeters, and a real-time muck weighing system, which can effectively control ground settlement and improve project quality through multiple measures. Through test sections, the expert team summarized the tunneling parameters for passing beneath fracture zones and soft-hard uneven composite strata, and during construction derived control measures for segment uplift in granite strata, enriching shield construction techniques and methods and laying a solid foundation for ensuring efficient and safe shield construction.

The second phase of Qingdao Metro Line 2 has a total length of 8.9 kilometers, including 8 stations and 10 sections. It is a major transportation artery connecting eastern Licang with the central urban area of Licun, and is of great significance for improving the network structure of the east coast urban area and driving the planned development of eastern Licang District and the Expo Park area. Once put into use, it will greatly improve the traffic environment along the line and the travel conditions of citizens.