All 14 shields along the west extension of Line 7 started.

Text/Figure Jinyang Net reporter Wang Haijun

Correspondent Xu Shufan Tang Yongmao

Recently, with the huge roar of the cutter head of the "Endeavour" shield machine rotating, the right line shield of Lintou to Nanyong Station (hereinafter referred to as "Linnan Section") in the west extension section of Line 7 started smoothly, marking that all the shields on the whole line have started. On the same day, the shield machine "Urban Rail Youth" on the left line of the section from Meidi Avenue to Beijiao Xincheng Station (hereinafter referred to as "Meibei Section") successfully went out of the tunnel after overcoming multiple construction challenges (all tentative names of the project).

All shields on the whole line have been launched.

According to the subway company, the west extension section of Line 7 has a total length of 13.447 kilometers, with a total of 8 stations. Among them, there are 3 transfer stations and 1 Yifeng parking lot. According to the construction plan, a total of 14 shield machines were put into tunnel excavation in the west extension section of Line 7, and the smooth start of the right line shield in Linnan section marked the completion of all shield start-up work in the whole line.

It is understood that the left tunnel of Linnan section in the west extension section of Line 7 is 1002 meters long and the right tunnel is 998 meters long. The shield machine starts from Lintou Station and extends eastward along National Highway 105. It will pass through Tanzhou Waterway with a length of about 135 meters, pass through the pile foundation of 110KV overhead electric tower and Lintou Bridge, and finally reach Nanyong Station. In order to ensure the smooth excavation of Endeavour, subway builders have formulated safe and feasible construction schemes and measures in combination with the previous initial experience to ensure the safety and order in the initial and excavation process.

Establishing systematic risk prevention and control system to overcome multiple construction problems

It is reported that the left line shield between the North and the United States started in March this year. The "Urban Rail Youth" used is an earth pressure balance shield machine, with a total length of 85 meters, an excavation diameter of 6.47 meters and a total weight of about 500 tons. In the process of shield tunneling, subway builders reinforced the stratum with triaxial mixing piles for 15 months, and the total length of interval reinforcement was 2.3 kilometers, accounting for 60.2% of the total length of interval lines, which greatly improved the geological conditions of shield tunneling and successfully solved many problems such as soft stratum construction.

In order to ensure the smooth progress of the shield machine, the project invited experts to demonstrate the major hazards and risk points of the project for many times, analyzed and demonstrated the risk points, and established a systematic risk prevention and control system. For example, according to the risk characteristics of shield construction, a special emergency plan for safety is compiled. According to the characteristics of shield initiation construction risk, an emergency leading group for shield initiation was established to prevent shield construction risk and solve shield construction problems. In addition, targeted safety and technical disclosure training has been given to field workers for many times to ensure the safety of shield construction.

Up to now, 46% of the civil works in the west extension section of Line 7 have been completed. Among the eight stations, three main structures have been capped, and the remaining five are under civil construction; Of the eight sections, two have been connected, and the remaining six are under civil construction. Yifeng parking lot and access section line shall be subject to civil construction.