Recently, the section from the entrance of the Wujiayuan Tunnel to No. 1 inclined shaft of the Xi'an-Yan'an High-speed Railway, constructed by China Railway No. 3 Engineering Group Co., Ltd. under the commissioning of the Xi'an-Chengdu Passenger Dedicated Line Shaanxi Company, was successfully holed through, marking another major progress in the construction of a long tunnel on the entire Xi'an-Yan'an High-speed Railway line and laying a solid foundation for the subsequent construction of ballastless track.

The Wujiayuan Tunnel of the Xi'an-Yan'an High-speed Railway is located in the loess gully and ridge area of Yijun County, Tongchuan City, Shaanxi Province. In this area, gullies are developed and the terrain is undulating; the gullies are all V-shaped with varying cutting depths. The ground elevation ranges from 890 to 1,210 m, with a relative height difference of about 320 m. The tunnel generally has a burial depth of 50 to 100 m, with a maximum burial depth of 190 m and a minimum burial depth of 2.3 m. The tunnel passes through a loess ridge and mound area, where the terrain is complex, the soil is soft, and the soil has low cohesion, poor self-stability and high safety risks.

To ensure the safety and quality of tunnel construction, the construction party strictly implemented construction standards and continued to deepen the creation of premium projects. During tunnel construction, the advance footage was strictly controlled; in shallow-buried sections, the CRD method was used to divide the cross-section, effectively controlling settlement and ensuring construction safety. Adhering to the principle of "advanced pipe forepoling, short excavation, strong support, frequent measurement and early closure," the project adopted mechanical excavation assisted by manual work, applied shotcrete to promptly seal the excavated face, and used advanced small conduit support, steel arch support and wire mesh hanging to enhance the self-stability of the surrounding rock. At the same time, regular investigations were carried out to identify hidden risks in tunnel construction safety and quality, and real-time monitoring and feedback were conducted on in-tunnel and surface monitoring measurements as well as the condition of the surrounding rock at the tunnel face. During construction, the project department scientifically optimized the construction organization plan, using the three-bench method with temporary invert to achieve rapid excavation and rapid support with timely closure, thereby enhancing the overall deformation resistance of the tunnel and strictly controlling tunnel settlement and deformation. This effectively solved the difficulties of low bearing capacity and easy deformation of collapsible loess foundations, ensuring the smooth holing-through of the tunnel.

The Xi'an-Yan'an High-speed Railway is the first high-speed railway in the old revolutionary base area of northern Shaanxi and an important part of the Baotou (Yinchuan)-Haikou high-speed railway corridor in the national high-speed railway network. Together with the Xi'an-Chongqing High-speed Railway under construction, it forms a major north-south corridor. It is an important component of the main framework of Shaanxi Province's "米"-shaped high-speed railway network and a key construction project during the 14th Five-Year Plan period. The line has a total length of 299.8 km and is built to the standard of a double-track high-speed railway with a design speed of 350 km/h. After the line is completed and put into operation, the travel time from Xi'an to Yan'an will be shortened from the current 2.5 hours to about 1 hour. This is of great significance for further advancing the Western Development Strategy, helping 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 hub status in the national railway network.