At 5 a.m. on July 7, the shield machine on the left line of the Yangli Station–Intermediate Ventilation Shaft section of the Fuzhou Metro Line 2 East Extension Project undertaken by China State Construction Engineering Corporation (CSCEC) completed excavation and segment assembly of the 565th ring, marking that the shield machine has successfully crossed the F1/F2 fault zone. At this point, both shield tunnels in the section have successfully crossed the major risk source of the fault zone.

The single-line length of this section is about 1.7 km, crossing one fault zone (the combined action of the F1/F2 fault zones) and 16 densely jointed and fissured zones. The strata within the tunnel range are mainly slightly weathered granite (average rock strength about 160 MPa, with a maximum of 245.5 MPa), with locally occurring moderately weathered granite and silt mixed with boulders. Two EPB/TBM dual-mode shield machines were used for excavation, and the construction was highly difficult. The F1/F2 fault zone is about 31 m long (left line: rings 540–565; right line: rings 537–562), with broken rock strata. The ground surface above is the plant of Haiwang Pharmaceutical Factory, and the zone is prone to collapse, shield jamming, water inrush and other hazards, making it a major risk source in this section.

The project attached great importance to risk control for crossing the fault zone and organized Civil Works Section 1 to strictly adopt various measures: First, detailed investigation and verification—multiple on-site surveys were organized and coordination was carried out with the property owner, supplementary geological exploration and pumping tests were conducted in advance at the fault zone location, and the geological conditions and ground conditions were investigated in detail; Second, full discussion and demonstration—expert consultation meetings were organized multiple times to plan in advance pretreatment measures for the risk source and technical measures for the shield tunneling underneath; Third, advance reinforcement and pretreatment—the design was coordinated to refine the ground grouting reinforcement scheme, and grouting reinforcement pretreatment was arranged before crossing; Fourth, ensuring the shield machine's working condition—a comprehensive inspection of the shield machine was carried out before crossing, the tool wear replacement standard was raised, and the tunneling parameters during crossing were strictly controlled; Fifth, close monitoring and supervision—a 24-hour leadership duty system was implemented, all tunneling parameters were monitored throughout the process, and settlement monitoring of the pharmaceutical factory plant and the completed tunnel was intensified.

Through the above series of measures, the right-line shield machine crossed the F1/F2 fault zone between May 7 and May 10 (72 hours in total), and the left-line shield machine crossed the F1/F2 fault zone between July 3 and July 7, 2024 (79 hours in total), with an average crossing performance of more than 9 rings per day. This created a good foundation for the subsequent construction and breakthrough of the shield tunneling in the Yangli Station–Intermediate Ventilation Shaft section, and also won unanimous praise from the owner and all participating construction units.