On April 15, the right line of the Longtang Depot Access Line section of Phase I of Hefei Rail Transit Line 6 was successfully holed through, becoming the 29th single-tube shield-driven section to be completed on this line.

　　The right line of the Longtang Depot Access Line section has a total length of approximately 1,071 meters and a total of 784 segment rings were assembled. The shield machine was launched from the Longtang Parking Lot, successively passed beneath multiple gas pipelines and the Sanshibu River Bridge, then bored westward along Heping Road and was received at Dongfeng Avenue Station. Shield tunneling in this section is characterized by small-radius and steep-gradient construction, and it passes beneath multiple risk sources, making construction difficult and safety risks relatively high.

　　To ensure the safe and smooth holing-through of the shield-driven section, Hefei Rail Transit held multiple shield construction planning meetings and invited experts to conduct demonstration and review. In response to the construction difficulties of steep-gradient tunneling and small-radius turning in the section, during shield tunneling Hefei Rail Transit adopted a combination of simultaneous grouting and secondary two-component grouting to ensure that the formed tunnel segment rings in the small-radius circular curve section do not undergo lateral displacement, while promptly filling the surrounding rock voids to ensure soil stability. At the same time, the tunneling posture of the shield machine was monitored in real time on site; based on the soft and hard distribution of the strata, partitioned operation of shield advancement was carried out, thrust and advance speed were set, and intensive monitoring of the surrounding environment such as road surfaces, buildings and pipelines was simultaneously conducted, achieving precise control of shield posture and ground settlement and successfully completing the goal of holing through the section.

　　Up to now, of the 17 stations in Phase I of Hefei Metro Line 6, the main structures of 14 stations have been topped out, and 29 of the 36 single-tube shield-driven sections have been holed through.