On March 5, Hefei Xinqiao Airport Line S1 marked new progress as the left line of the section from International Town Station to Aviation Industrial Park Station was successfully holed through, becoming the third single-track shield-driven section of Line S1 to be completed.

　　It is reported that the left line of the "Guohang" (International Town–Aviation Industrial Park) section of Hefei Xinqiao Airport Line S1 has a total length of approximately 1,872 meters and comprises 1,249 assembled ring segments. The shield machine was launched from International Town Station and successively passed beneath multiple risk sources, including Hualian Road, underground pipelines, and a greenway bridge. In particular, between rings 340 and 780, it had to traverse a water-rich sandstone stratum totaling 660 meters, where there was a risk of tunnel water and soil inrush, and where ground settlement and shield attitude control were highly challenging.

　　To ensure the safe and smooth holing-through of this section, in response to the various difficulties encountered during shield tunneling, Hefei Rail Transit made meticulous plans and repeatedly invited experts for demonstration and review. After comprehensive consideration of all aspects, the excavation mode of "critical combination of earth pressure and compressed air, with ring sealing for water stoppage" was ultimately adopted. When the balanced earth pressure provided in the excavation chamber was insufficient, compressed-air pressure-holding measures were promptly taken to maintain balance, effectively controlling the shield tunneling attitude. In addition, "ring sealing for water stoppage" was carried out after every two rings of segment assembly, effectively reducing the risk of tunnel water and soil inrush. Ultimately, the shield successfully passed through the 660-meter water-rich sandstone stratum, achieving controllable tunnel attitude within the bore and ground settlement meeting the design specification requirements, thereby accomplishing the section holing-through objective.

　　As of now, the main structures of six stations on Hefei Xinqiao Airport Line S1 have been topped out; of the 18 single-track shield-driven sections, three have been holed through and ten are currently being excavated.