On February 1, 2023, the single-pipe double-layer shield tunnel with the largest diameter in China, designed by the Fourth Railway Academy and undertaken by the China Railway Fourteenth Bureau, was successfully completed.

This breakthrough provides a successful case for opening up the city's dead end road, protecting ancient city relics and scenic spots, and developing and utilizing underground space.

Wuchang Snake Mountain is located on the east bank of the Yangtze River. Zhongshan Road cuts off Heping Avenue, making it a dead end road. Therefore, Linjiang Avenue must be detoured from Zhongshan Road to Zhangzhidong Road, resulting in an increase of 4.1 kilometers for vehicles.

In this regard, in the preliminary construction planning, the construction team plans to use a mud-water balance shield machine with an excavation diameter of 16.03 meters for the construction of the southern extension of Heping Avenue. , Vehicles can go directly from Zhongshan Road to Zhangzhidong Road in 5 minutes through the tunnel, which can effectively relieve the traffic pressure in the east-west direction of Wuchang along the river and greatly improve the efficiency of urban traffic.

Effect drawing of single hole two-way six-lane

However, it is not easy to get through this dead end...

Workers operating cranes to install segments

Because it is located in the core area of the city, the tunnel excavation process faces many major risk sources. The tunnel passes through the ancient city of Wuchang, the Beijing-Guangzhou Railway and other places. There are more than 500 old buildings on the line and many former residences of celebrities. Moreover, the geological conditions of shield excavation are complex, including hard rock, uneven soft and hard strata, and karst cave areas, and the karst cave penetration rate is as high as 40.5%. Among them, the maximum rock strength is as high as 200 MPa. During the shield excavation, the machine stopped several times to change the cutting tools.

In addition, the horizontal distance from the tunnel of Metro Line 5 in operation is only 10 meters, and shield tunneling hard rock excavation is likely to cause disturbance to the formed tunnel of Line 5, which is one of the tunnels with relatively high technical content and difficulty in domestic construction.

The shield captain manipulates the shield machine to move forward

In view of the characteristics, difficulties and risks of the above-mentioned projects, China Railway 14th Bureau's large shield machine has given full play to its core technical advantages, designed and optimized the shield machine in a targeted manner, and invited experts such as Qian Qihu, an academician of the Chinese Academy of Engineering, to guide and check the construction problems.

During the excavation process, the construction team applied automatic monitoring construction technology, arranged observation points for sensitive buildings and structures along the line, monitored the settlement data in real time, and adjusted the excavation parameters synchronously to achieve a safe and smooth crossing.

Formed tunnel

It is reported that the south extension project of Wuhan Heping Avenue is planned to be completed and opened to traffic by the end of 2023. It will effectively improve the traffic conditions in the ancient city of Wuchang, relieve the traffic pressure on Zhongshan Road-Baishazhou Avenue, and form a backbone traffic channel in the direction of Wuchang Shunjiang. Editor / Zhao E