At around 15:00 on April 22, the "Qianjin No. 1" shield machine finally broke through the surface. The shield tunnel section of the Shi-Gao interval of Section 14 of Guiyang Metro Line 3, constructed by China Railway Sixth Group, was safely and smoothly completed by Guizhou Province's first "Qianjin No. 1" shield machine, currently the longest tunnel in the region.

According to reports, since the "Qianjin No. 1" shield machine was launched in September 2020, it has overcome various difficulties such as a large design slope, high water pressure, numerous karst caves, hard rock layers, and the fact that this section is located in residential areas. The entire process took 240 days, with 1,482 linear meters excavated and over 190 structures crossed underneath.

This interval has a 27‰ upward slope. Due to the abundant confined groundwater in the karst landscape, segment uplift was relatively serious. To overcome this problem, the construction unit conducted multiple grouting mix ratio tests and debugged the optimal ratio suitable for Guiyang's strata, increasing the slurry consistency and shortening the initial setting time, thus solving the problems of incomplete slurry filling and segment uplift in water-rich strata. The minimum curve radius of the tunnel is 500 mm. To control tunnel quality, strict control was exercised over segment quality, type selection, and segment installation, achieving zero misalignment and effectively controlling tunnel quality. In response to karst caves, the construction unit applied two treatment methods: the first was ground supplementary exploration, grouting the karst caves from the ground surface; the second was the shield machine's advanced prediction system. The shield machine's built-in advanced prediction detects the strata ahead through vibrations generated by the cutterhead cutting the tunnel face. Upon discovering karst caves, grouting was performed through advance grouting holes. This effectively prevented a series of hazards such as the shield machine pitching downward.

At the same time, to ensure the safe and smooth completion of this interval, the project department optimized various construction plans and emergency plans in advance, and constantly monitored various surface data during construction: settlement and noise at each monitoring point, as well as vibrations caused by the shield machine, striving to optimize all values to the extreme and minimize the impact of construction on residents' living environment.