On January 24, 2022, with a loud explosion, the Yongshun Tunnel of the Guinan High-speed Railway was safely connected, which means that the tunnel project between Nanning and Hechi in the Guangxi section of the Guinan High-speed Railway was fully completed, laying a solid foundation for the track laying in the middle of 2022. .

Yongshun Tunnel, located in Hechi City, Guangxi, has a total length of 11,014 meters. The area where the tunnel is located is a typical karst karst landform. The tunnel body passes through two fault zones successively. The geological conditions are very complex, and it is easy to cause problems such as landslides, water and mud inrush, and rock bursts. The organization is complex, and it is very difficult to ventilate, exhaust and discharge water. It belongs to the first-level risk tunnel with the highest risk level in China's high-speed railway tunnels. If the traditional two-end excavation method is used for construction, it may affect the progress of the tunnel construction.

Yunnan-Guangxi Railway Guangxi Company and China Railway 11th Bureau refer to the construction experience of many extra-long tunnels at home and abroad, and adopt the parallel pilot tunnel construction method for construction. They dug a parallel auxiliary tunnel next to the entrance of Yongshun Tunnel. Through the cross passage between the pilot tunnel and the excavated tunnel, they increased the number of tunnel working surfaces to 10 in one fell swoop. At the fastest time, they can move forward 40 meters per day. Compared with the traditional construction method, it is 5 times higher than that of the traditional construction method, so that the tunnel can be penetrated 3 months ahead of schedule. This tunnel has also become the tunnel with the largest construction work area and the fastest advancing speed on the whole line of the Guinan high-speed railway.

Due to the long length of Yongshun Tunnel, the natural ventilation is not smooth. Even in the current cold winter, the temperature inside is still as high as 30 degrees. Traditional ventilation equipment can usually only meet the construction requirements of a 1-kilometer tunnel. During the construction of a long tunnel, multiple ventilation equipment is required to operate at the same time, which is not only expensive, noisy, but also unsatisfactory.

The construction unit set up a research group on ventilation technology, and developed China's first low-noise frequency conversion tunnel dedicated counter-rotating fan. Each counter-rotating fan can meet the construction needs of 3 kilometers, improve the air quality in the tunnel, and ensure the tunnel construction. Safety, fills the blank of the difficult ventilation problem of China's long tunnels.

Now is the Spring Festival, and many migrant workers have already embarked on their journey home. Although the current tunnel has been completed, there are still more than 100 construction workers sticking to their posts during the Spring Festival. Yuan Zhonghua, the project manager of the Guinan High-speed Railway Project Department of the China Railway 11th Bureau, said that they will concentrate on the comprehensive construction of the tunnel ditch cable trough, inverted arch and secondary lining to ensure that the tunnel construction will be completed by June 2022.

The Guinan high-speed railway runs through northwestern Guangxi and southeastern Guizhou. It is the first high-speed railway in Guangxi with a designed speed of 350 kilometers per hour. At present, 96.3% and 94.4% of the total designed subgrade earth, rock and bridge works of the Guangxi section of the railway have been completed. 41 of the 44 new tunnels have been successfully connected, accounting for more than 90%, and the ballastless track project has been fully started. The entire line of the project is expected to be put into operation in 2023, when the travel time from Nanning to Guiyang will be shortened from the current five hours to about two hours. Editor/He Yuting