After the two shield tunneling machines in the Meiyin shield tunneling section of the Meishan segment of the Chengdu-Meishan S5 Line were started up, two more shield tunneling machines were hoisted and lowered into the shaft in the section from Yinyue Square Station to Meishan East Station.

The tunnel on the Meishan segment of the Chengdu-Meishan S5 Line passes beneath the core area of Meishan's urban district, connecting three stations: Meishan East Station, Yinyue Square, and Meishan North. The underpass tunnel in the Meishan urban area has a total length of approximately 4.5 kilometers, with a complex construction environment and high construction risks. To ensure the smooth launching and tunneling of the shields, the project team of the Chengdu-Meishan S5 Line under Shudao Group carefully planned and conducted multiple studies to formulate a tunneling scheme, thereby ensuring good equipment performance. The two shield machines No. 8 and No. 9 deployed this time were launched in both directions from Meishan East Station and are tunneling simultaneously toward Yinyue Square, so that the Meishan segment will have four shield machines tunneling at the same time, ensuring that the tunnel on the Meishan segment of the Chengdu-Meishan S5 Line is completed and holed through with guaranteed quality and quantity.

The shield machine used in the project has a maximum excavation diameter of 8.24 meters, a total length of 110 meters, a weight of 1,000 tons, and a total installed power of 4,100 kilowatts. It is equipped with 118 cutters of various types, and the cutterhead opening ratio is 38%, maximally meeting the demands of the complex strata encountered during tunneling. The overall assembly of the shield machine has reached an advanced level in the industry. What was hoisted and lowered into the shaft this time is the main drive part, the "heart" of the shield machine and its core component. It is equipped with 12 sets of motors and 38 telescopic cylinders, providing a continuous source of kinetic energy for the shield machine during tunneling, playing the role of power conversion and output, and serving as the power output center of the shield machine's cutterhead. The No. 4 trailer lowered into the shaft at the same time is the rearmost end of the shield machine's backup trailer system, carrying components such as the pipe changer, pipe-changing crane, and water and air hose reels, and mainly responsible for extending the various pipelines of the shield machine.