On June 7, after more than 1,300 days and nights of intensive work, the left tube of the Baiyashan Tunnel—a high-altitude loess extra-long tunnel on the Zhuoni-Hezuo Expressway, a major provincial construction project in Gansu Province—was holed through. With this, both the left and right tubes of the extra-long tunnel have been successfully holed through, removing a major obstacle to the expressway's early completion and opening to traffic.

The 121.308-kilometer Zhuoni-Hezuo Expressway is an important component of the second transverse line of Gansu Province's expressway network. The project connects directly with the Dingxi section of the expressway from Feng County, Shaanxi Province, to Hezuo in Gannan Prefecture, Gansu Province. Running from east to west through Zhuoni County and Lintan County to Hezuo City, it connects via a T-shaped interchange with the proposed Hezuo-Sairilong section of the Wuhai-Maqin Expressway.

The Baiyashan Tunnel, which passes through Tawa Village in Yangyong Town, Lintan County, and Pocha Village in Karqin Town, Zhuoni County, is a separated extra-long tunnel with a left tube 3,680 meters long and a right tube 3,660 meters long, at an average altitude of 2,776 meters. It is a key and difficult control project in Phase I of the Zhuoni-Hezuo Expressway. The tunnel site area features a terraced plateau loess hilly landscape with high mountains and deep valleys and a dense network of crisscrossing gullies. The alignment passes through plateau loess silt and fissure zones. The tunnel portal is located in a landslide body section on a mountain slope. The tunnel passes entirely through Grade IV and Grade V surrounding rock, with well-developed rock joints and fissures and extremely poor integrity and self-stabilization capacity. Mud bursts, water inflow, rockfall, collapse, instability and deformation are highly likely to occur, posing major safety risks to tunnel excavation.

According to Mi Yongzeng, the on-site project manager of the Municipal Engineering Company of China Railway 20th Bureau Group, in the face of construction challenges such as the variable plateau climate, a scientific research task force was set up to repeatedly demonstrate special plans and formulate response measures for each type of risk one by one. During construction, "total quality management" was implemented; strictly following the principles of "advance pipe forepoling, short advance per round, rapid sealing, and frequent measurement," measures featuring "horizontal coverage to the edges, vertical coverage to the bottom, three-dimensional networking, and effective control" were adopted to strengthen whole-process control. The full-staff safety production responsibility list system was implemented, common quality problems were overcome, and the "dual zero" safety goal was pursued. Work quality was used to ensure process quality, and process quality to ensure project quality, ensuring all-round standardized construction and safe production and achieving first-time quality excellence in the project. On May 28 this year, the right tube of the Baiyashan Tunnel was holed through first.