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As the cutterhead of the 'Guangqu No. 1' shield machine broke through the soil

Constructed by China Railway 14th Bureau Group

Beijing Subway Line 17 Project Lot 12

Left line of the southern section between Guangqumenwai Station and Yong'anli Station

Successfully completed

During the period, it passed beneath an operating station, a super-risk source

The maximum settlement data was only 0.9 mm!

△ Shield machine breakthrough scene

△ Group photo at the breakthrough of the southern section shield tunnel

The project is located between the 2nd and 3rd Ring Roads in Chaoyang District, Beijing, in a bustling urban area near the CBD core, surrounded by numerous buildings with a complex geographical location. The lot includes one station and one section: Guangqumenwai Station and the section from Guangqumenwai Station to Yong'anli Station (referred to as the Guang-Yong section), with a total length of 1.7 km.

△ Lot project route map

During the construction of the left tunnel of this section, a super-risk source had to be tackled: the shield passing beneath the existing operating Guangqumenwai Station of Line 7. The closest distance between the outer edge of the left line shield cutterhead and the auxiliary No. 2 ventilation duct structure of the existing station was only 3.85 meters. After completing the crossing, the shield was received beneath the existing operating station, posing great construction difficulty and high operational risk.

During shield tunneling, the project department strictly implemented various risk control measures, strictly controlled shield advancement parameters, maintained stable earth chamber pressure, controlled shield attitude, reduced ground loss during shield advancement, timely performed synchronous grouting of segments, established a sound construction coordination mechanism, conducted daily inspections inside the station, and intensified settlement monitoring of the existing line structures.

Through the efforts of the project team, the shield successfully completed the task of passing beneath the super-risk source and was smoothly received beneath the existing operating station. According to monitoring data from a third-party monitoring unit, the maximum settlement of the existing line's auxiliary structures was only 0.9 mm, and during the tunneling of the left line of the southern section, settlement values were all controlled within 5 mm.

△ Segment tightening measures in the empty-push section

In addition, during construction, to ensure optimal shield launching conditions, mined tunnels using the mining method were set up on the north and south sides of the launching shaft. The shield was launched, pushed empty, and segments were assembled inside the mined tunnel, making it difficult to control segment forming quality. To ensure segment forming quality, the tunnel company organized an expert meeting on shield empty-push launching construction, optimized the construction measures for shield empty-push launching, and took measures to prevent segment uplift. In the empty-push section, on the basis of the original design tightening measures, radial and circumferential tightening measures were added, successfully completing the shield empty-push section construction with good segment forming quality.

Beijing Subway Line 17 is located in the eastern part of Beijing and is a north-south rail transit trunk line. The line connects four administrative districts: Changping, Chaoyang, Dongcheng, and Tongzhou. It supports and promotes the development of Future Science City, CBD, Chaoyang Port, Fatou Industrial Zone, and the station front area of Yizhuang New Town. It also serves key residential areas such as Tiantongyuan, Wangjing West, Taiyanggong, and Panjiayuan, bringing convenience to residents in the eastern part of the city and enabling rapid guidance and evacuation of passenger flow.