On the 7th, two shield tunneling machines, "Shaoshan No. 1" and "Shaoshan No. 2," were successfully launched at Yuntang Station and Huanbao Avenue Station respectively, marking that the first phase of Changsha Metro Line 7 has officially entered the shield tunneling stage. This project will further improve Changsha's rail transit network and drive economic development along the route.

Two shield tunneling machines launched on the same day

The first phase of Changsha Metro Line 7 is a north-south backbone line of Changsha's rail transit network. It starts at Yuntang Station and runs along Huijin Road, Shaoshan Road and Bayi Road, with a total length of 16.836 kilometers. All stations are underground, with 16 stations in total, including 9 transfer stations, comprising 18 shield tunneling sections and 1 depot access line. The "Shaoshan No. 1" and "Shaoshan No. 2" composite earth pressure balance shield tunneling machines launched on the 7th have an excavation diameter of 6.44 meters, a total length of 83 meters, and an overall equipment weight of about 450 tons.

"The 'Shaoshan No. 1' shield tunneling machine was launched from the north end of Yuntang Station, tunneling northward along Huijin Road, passing through Huanbao Avenue Station before continuing to Wanfunan Road Station where it will be lifted out," said Zhang Hong, project manager of Work Zone 4, Section 1 of Changsha Metro Line 7 under China Construction Fifth Engineering Division. The section is about 2 kilometers long, with geology consisting of strongly and moderately weathered argillaceous siltstone; the section passes beneath the pedestrian passage of Changsha University of Science and Technology, the roadbed of the South Third Ring Expressway, and a rainwater box culvert, and passes alongside residential communities such as Fengchangyuan and Jinhuiyuan.

According to reports, the "Shaoshan No. 2" shield tunneling machine was launched from the north end of Huanbao Avenue Station to the ground level of the South Third Ring Depot. The section has a total length of 438.1 meters. The tunneling process passes through strongly and moderately weathered argillaceous siltstone and faces difficulties such as "small radius," "shallow cover," and "large slope." The plan adopts an extreme small curve radius of 250, the tunnel burial depth at the shield receiving end is less than 4 meters, and the longitudinal slope is 32‰, making construction relatively difficult.

It is Changsha's first fully automated operation line

According to reports, in response to complex construction conditions, the construction team gave full play to the leading role of Party building, established a technical task force and a joint support team with Party members as the backbone, formulated special construction plans and emergency response plans, organized emergency drills, advanced refined on-site management, and strictly controlled the shield machine admission, approval of hazardous major plans, operator qualification, material entry, and equipment maintenance, safely and efficiently completing key links such as shield machine hoisting, installation and commissioning, and acceptance of launch conditions, ensuring that the shield machines were launched safely and smoothly on schedule.

Line 7 passes through the Provincial Government Cluster, Muyun Cluster, Hedong Center and Xingsha Area, connecting three transportation hubs—South Bus Station, Changsha Railway Station and East Bus Station—and three important commercial districts—Hongxing, Dongtang and Yuanjialing. It also links four large hospitals—Changsha Central Hospital, the First Affiliated Hospital of Hunan University of Chinese Medicine, Changsha Hospital for Maternal and Child Health Care, and the Second Xiangya Hospital—and four universities—Changsha University of Science and Technology, Central South University of Forestry and Technology, Central South University, and Hunan University of Chinese Medicine. It is Changsha's first line to adopt a fully automated operation system.

Up to now, all 16 stations of Line 7 have started construction. Among them, the main structures of 2 stations (Huanbao Avenue Station and South Bus Station) have been topped out, 11 stations including Yuntang Station are undergoing main structure construction, 1 station (Zhengtangpo Road Station) is undergoing earthwork excavation, 1 station (Yuanjialing Station) is undergoing construction of the station's main retaining structure, and 1 station (Dongtang Station) is undergoing traffic diversion construction.