On the 10th, the first shield machine of the Phase III project of Hefei Rail Transit in Anhui Province, "New Journey No. 1", was successfully launched at Yujiu Road Station on the eastern extension of Hefei Metro Line 2, marking that the Phase III project has fully entered a new stage of shield tunneling construction.

According to reports, the Phase III project of Hefei Rail Transit includes 6 lines and 73 stations, with a total of 92 shield machines. The total designed earthwork volume is 17.096 million cubic meters, the total designed main structure (slabs) is 1,394 pieces, and the total designed retaining piles are 31,297.

The launch station for this shield machine is an underground two-story island-type station. The station has a total length of 208.6 meters and a standard section width of 19.7 meters, and is constructed using the open-cut sequential method. Since the start of construction, the station has progressed rapidly, setting a new speed record for Hefei rail transit engineering construction. The station's retaining piles were completed 38 days after construction began; station earthwork excavation began 82 days after construction began; the station earthwork excavation was completed in 55 days; the shield machine was lowered into the shaft 190 days after construction began; and the main structure of the station was capped 198 days after construction began.

The shield machine at this station was hoisted and lowered into the shaft on May 20. To ensure the smooth launch of the shield machine, Hefei Rail Group led the participating units to safely and efficiently complete the shield machine assembly and debugging, reaction frame installation, negative ring assembly, horizontal probe drilling, launch condition acceptance, and other work. After a successful launch, the shield machine will begin tunneling at a speed of 10 to 15 meters per day under 24-hour informatized monitoring.

In addition, other lines under construction in the Phase III project are also advancing rapidly. Since the start of construction, multiple construction milestones have been completed in succession. For example, the first shield machine on the southern extension of Hefei Metro Line 3 has completed hoisting and lowering into the shaft and is about to be launched for tunneling. The main structure of the first elevated station on the southern extension of Hefei Metro Line 4 has been capped, and the first stations on Phase I of Hefei Metro Line 6, Phase I of Line 7, and Phase I of Line 8 have begun excavation of the main foundation pits.

It is understood that in the first five months of this year, Hefei Rail Transit engineering completed a cumulative fixed investment of 5.176 billion yuan, a cumulative earthwork excavation of 1,908,391 cubic meters, a cumulative pile foundation construction of 16,338 piles, a cumulative concrete pouring of 724,604 cubic meters, and a total track-laying mileage of 35.4 kilometers.

The shield machine is a giant 80 meters long and weighing 400 tons. It is like a giant mechanical pangolin, digging tunnels 20 meters underground. The shield machine will pass under buildings, bridges, and rivers, and will also encounter obstacles such as water inflow, collapse, and karst caves. For a shield machine with a diameter of 6 meters, if the tunneling deviation in the darkness exceeds 5 millimeters, it will cause damage to shield machine components and rupture and water leakage of segment linings, and shield equipment worth tens of millions may be at risk of being scrapped.