On August 25, after 1,144 days, the Wujiayuan Tunnel of the Xi'an-Yan'an High-Speed Railway was successfully holed through, marking the safe and smooth completion of all Grade I high-risk tunnels on the Xi'an-Yan'an High-Speed Railway.

The photo shows the tunnel portal

The Xi'an-Yan'an High-Speed Railway is an important component of the Baotou (Yinchuan)-Haikou Corridor of China's "Eight Vertical and Eight Horizontal" high-speed rail network, running from Baotou and Yinchuan to Haikou. The line has a total length of 299.8 kilometers and is constructed by Xi-Cheng Passenger Dedicated Line Shaanxi Company. The Wujiayuan Tunnel is located in the loess gully and ridge area of Pengzhen, Yijun County, Tongchuan City, Shaanxi Province. It is designed as a single-tube, double-track tunnel, and its geological conditions are extremely complex, passing through sections with extremely high risks such as loess, soil-rock interfaces, shallow cover, and water inflow. The maximum burial depth is 190 meters and the minimum is 2.3 meters, making construction difficult and safety risks extremely high.

Since the start of construction, the construction unit has strictly implemented the standardized construction requirements of Xi-Cheng Passenger Dedicated Line Shaanxi Company, adopting a combination of advanced geological forecasting, surrounding rock monitoring and measurement, and other means to conduct comprehensive analysis and judgment of the tunnel's geological conditions, and to identify in advance the location, nature, and scale of unfavorable strata. At the same time, blasting and mechanical excavation with manual assistance were adopted.

Loess tunnel construction fears water the most; excessive water content causes the soil to become soft and plastic, weakening the self-stabilizing capacity of the surrounding rock. As water inflow brings considerable construction risks, to solve the water inflow problem, the project department adopted measures such as infrared water detection and sealing, plugging, and drainage to treat water outlets in advance, and used methods such as staged pumping stations and automatic pumping to promptly remove water from the tunnel, ensuring a safe working environment.

In addition, the project team increased exchanges and cooperation with research institutes and universities. Through research on the crystallization formation mechanism and prevention technologies of the tunnel drainage system, they summarized and formed three patents, including "A Tunnel Drainage Pipe Cleaning Device," eliminating tunnel defects caused by crystallization blockage of drainage blind pipes and ensuring the physical quality of the tunnel project.

It is reported that after the Xi'an-Yan'an High-Speed Railway is completed, the railway travel time from Xi'an to Yan'an will be shortened from the current two and a half hours to about one hour. This is of great significance for further advancing the Western Development Strategy, supporting rural revitalization in the old revolutionary base areas, accelerating the construction of the Baotou-Haikou High-Speed Railway Corridor, further improving and optimizing the layout of the national high-speed railway network, and enhancing Shaanxi Province's locational advantages and its position as a hub in the national railway network.