On the morning of January 20, the shield machine for the shield tunneling section between Shiqiao Station and Zhongyi Road Station (hereinafter referred to as the Shi-Zhong section) of Wuhan's first metro loop line, Line 12, successfully passed beneath Shiqiao Station of Line 6, marking that the shield machine has successfully broken through a Level-1 risk source and officially begun its "underground journey."

The shield launching station—Shiqiao Station of Line 12—is located on the east side of the intersection of Gusaoshu Road and Houhu Avenue, with a total length of 186 meters, a standard width of 22.7 meters, an end-shaft width of 27 meters, and a depth of about 32 meters, equivalent to the height of an 11-story building. It is the deepest station under construction on the Wuhan Metro and will, upon completion, provide a transfer with the already-operating Shiqiao Station of Line 6.

The shield machine had to pass beneath an existing line right from launch. This section is located on the first terrace of the Yangtze River, in water-rich soft soil strata, placing extremely high demands on tunnel settlement control. According to reports, during construction, how can the existing line be protected while allowing the line under construction to pass through smoothly? The construction contractor invited industry experts to repeatedly review the construction plan and, in stages, establish the construction parameters and control indicators for the shield passing beneath the existing line. At the same time, the currently safest shield launching technique—steel sleeve launching—was adopted.

According to reports, using a steel sleeve for the shield is equivalent to fitting a sealed steel sleeve over the shield machine, enclosing it within. During the launching stage, the shield machine can then tunnel entirely using normal excavation parameters, ensuring safe entry into the tunnel.

To ensure the smooth construction of the section's shield tunneling, the construction contractor deployed an experienced management and operations team and set up two specialized shield tunneling crews, upholding the principle of "safety and quality in parallel, efficiency and speed together," strictly controlling excavation parameters and shield machine attitude to ensure "zero settlement" in construction.

To guarantee on-site construction quality, Wuhan Metro Group, China Railway Construction Investment Group, and the construction contractor implemented graded risk management and control, with 24-hour on-site monitoring, strict control of process quality, duration, and coordination for key procedures, and daily monitoring and measurement to track safety conditions and ensure the safe completion of milestone targets. A simulation platform was also established to review the entire construction process through simulation, especially during the shield machine's passage through major risk sources, with experimental sections simulated in advance. The simulation replicates the same geological conditions to be excavated, followed by trial tunneling; after summarizing the data from the experimental stage, the actual crossing is then carried out. Shiqiao Station has four shield machines launching, all of which will use steel sleeves. The shield machine for the right line of the Shi-Zhong section, as the first shield machine launched at this station, will accumulate valuable experience for subsequent shield tunneling.