Recently, the earth pressure balance shield machine "Yong'an No. 1", jointly built by CRCHI and China Railway 14th Bureau Group, was successfully launched on the right line of the TJ7026 section of Ningbo Rail Transit Line 7. The earth pressure balance shield machine has an excavation diameter of 6.76 meters, an overall length of about 76 meters, an overall weight of about 450 tons, and an installed power of about 1,600 kilowatts.

Launch site of the "Yong'an No. 1" shield machine

The left line of the TJ7026 section of Ningbo Rail Transit Line 7 is about 2,884 meters long, and the right line is about 3,284 meters long. The shield machine mainly passes through strata such as silt, mucky clay, and silty sand, and construction is prone to causing phenomena such as the shield machine floating up and pitching down. The alignment passes alongside multiple high-voltage power towers, passes beneath 3 demolished-and-rebuilt bridge areas, 4 rivers, 1 expressway viaduct, and 1 interchange bridge. During construction, obstacles such as concealed piles and diaphragm walls exist, making shield machine construction highly difficult.

In response to the engineering characteristics of this project, CRCHI R&D technicians carried out targeted design for "Yong'an No. 1". For example, the shield tail grouting pipes adopt an external design, which effectively reduces the excavation diameter and lowers construction costs; the targeted design of the cutterhead and its cutters and the configuration of the low-speed propulsion system effectively solve the construction difficulties of the shield machine cutting piles and passing through diaphragm walls.

"Yong'an No. 1" shield machine rolls off the production line

The "Yong'an No. 1" shield machine launched this time is responsible for the right-line tunneling task from Minghai Avenue Station to Yufan Road Station. CRCHI and China Railway 14th Bureau Group cooperated in an orderly manner and efficiently advanced various tasks, completing the assembly and debugging of the shield machine to high standards in only 18 days, effectively ensuring the smooth launch of the "Yong'an No. 1" shield machine.