On July 19, the cutterhead of the "Qianjin No. 15" shield machine broke through the wall at the north end of Minzu University Station, marking the breakthrough of the right line of the Minzu University Station–Dongjiayan Station section of Guiyang Rail Transit Line 3. The section has now achieved double-line breakthrough.

The right line of the section is 1,631.4 meters long, with a burial depth of 8.6 to 14.7 meters. The section consists of fully weathered dolomite in full-face mode, and the stratum is relatively hard, causing severe wear to the shield machine's cutters during excavation. At the north end of Dongjiayan Station, dual-line shield construction is underway, and the station is handling segment hoisting, muck transport and other operations for four shield machines, making cross-operation construction difficult and risky. The section passes beneath buildings and structures including the Huaxi Avenue main traffic artery, the underpass trench and pedestrian passages, with a minimum vertical clearance of 3 meters, posing considerable safety risks.

The shield machine for the right line of the Minzu–Dongjiayan section was launched from Dongjiayan Station in late November 2020. During construction, the project department took multiple measures to overcome difficulties: first, it used in-tunnel HSP advanced detection to investigate the geological conditions around the tunnel face and took measures in advance; second, it reinforced the cutterhead for wear resistance to improve its durability and reduce cutter wear during excavation, and reasonably used foam agent to condition the muck and improve excavation efficiency; third, it formulated special construction plans and adopted continuous excavation and rapid passage methods to ensure the shield machine safely passed beneath risk sources; fourth, it adjusted the shield machine's attitude in a timely manner according to stratum conditions to ensure segment assembly quality met design specification requirements; fifth, for cross-operations, it organized special coordination meetings to effectively reduce the impact of cross-operations and ensure smooth construction.

Next, the project department will organize the safe hoisting, assembly and commissioning of the shield machine, and launch it again from the south end of Minzu University Station to ensure smooth excavation of the Guizhou University Station–Minzu University Station section and achieve tunnel breakthrough on schedule.