On August 23, the low-pressure tunnel of Shaft No. 3 of Construction Section II of the Xianyang Plateau Tunnel and Box Culvert works on the northern trunk line of Phase II of the Han-to-Weihe River Water Diversion Project was successfully holed through. The on-schedule completion of this major milestone marks the successful holing-through of the low-pressure tunnel of the deepest shaft on the northern trunk line of Phase II of the Han-to-Weihe River Water Diversion Project.

The main construction content of Phase II of the Han-to-Weihe River Water Diversion Project consists of three parts: the Huangchigou water distribution hub, the southern trunk line works and the northern trunk line works. The deepest shaft holed through this time belongs to Section II of the Xianyang Plateau Tunnel on the northern trunk line, with a shaft depth of 42.5 meters; the tunnel geology consists entirely of extremely unstable Class V surrounding rock and loess-like structures. The tunnel has poor geological conditions, high construction difficulty and high safety risks.

To ensure safe and efficient tunnel construction, the construction personnel carried out real-time monitoring of the surrounding environment, conducted thorough research and formulated a feasible construction plan, and for the first time applied "TPS + advanced detection technology" to this type of geological structure, further strengthening the geological sketching and geological forecasting of the excavation face, and implementing in a targeted manner the construction requirements of "strict water control, strong support, short advance, frequent measurement and early lining," thereby ensuring the smooth holing-through of the tunnel.

The Han-to-Weihe River Water Diversion Project is a backbone project of the national water conveyance and distribution works and one of the 150 major water conservancy projects that the state is accelerating from 2020 to 2025. According to the current project progress, the northern trunk line of the Han-to-Weihe River Water Diversion Project is expected to be fully completed by the end of 2025, and the southern trunk line is striving for completion in 2026. Once Phase II is fully completed, it will undertake water supply tasks for key cities such as Xi'an, Xianyang and Weinan, as well as 11 counties (cities and districts) and five new towns in the Xixian New Area, diverting 1.5 billion cubic meters of water from the Han River each year and benefiting more than 14 million people.