On November 30, a flow of water passed smoothly from the Zhangjiapo Tunnel in the Yuxi area of Chongqing into the Huangjinpo branch trunk line, marking the successful trial water delivery of the entire western trunk line of the Chongqing Yuxi Water Resources Allocation Project, in which Sinohydro Bureau 9 Co., Ltd. participated.

The Yuxi Water Resources Allocation Project is one of the 150 major water conservancy projects nationwide, and is also a major livelihood water conservancy project in Chongqing with the largest investment, the broadest coverage, and the largest beneficiary population. The project adopts an overall layout scheme of "large centralized clusters in the south, small grouped clusters in the north," with the southern section mainly consisting of the eastern trunk line, the western trunk line, and the Jialing River trunk line. The construction scope of Sinohydro Bureau 9 covers two branch trunk lines, Qingmingqiao and Huangjinpo, including 14 tunnels (totaling about 30 kilometers) such as the Shuangqiao Tunnel—the longest tunnel of the Yuxi project—and the Zhangjiapo Tunnel; 4 pumping stations including the Shijiawan Water Pumping Station and the Huangjinpo Booster Pumping Station; as well as pipe jacking and elevated water tanks, making it an important part of the western trunk line of the Yuxi project.

Since the start of construction, the project team has faced many complex situations and constraints. During the tunnel excavation phase, in response to problems caused by shallow tunnel cover and complex geological conditions, the project team used advanced technical means such as advanced geological forecasting and intelligent monitoring, combined with cantilever roadheader mechanical excavation and drill-and-blast construction techniques, effectively reducing risks and improving efficiency. During the tunnel lining phase, given the tight schedule and heavy tasks of the "11·30" trial water delivery target, the project team actively carried out technical research, using four sets of trolleys simultaneously for pouring at a single working face, greatly increasing the pouring speed while ensuring the flatness and compactness of the lining concrete. In terms of scientific and technological innovation, the project team researched and applied a construction method for large-flow sewage treatment in tunnels, eliminating the direct discharge of untreated wastewater; and innovatively proposed a tunnel dewatering method combining a permeable bottom-slab layer with drainage blind pipes, solving a major problem constraining tunnel progress and quality.

After the Yuxi Water Resources Allocation Project is fully put into operation, it will supply water for urban and rural domestic and industrial use in Yuxi by pumping water from the Yangtze River and the Jialing River, realizing interconnection and mutual adjustment and supplementation between Yangtze River water and Jialing River water. The benefited area will reach 11,800 square kilometers, effectively guaranteeing the domestic and industrial water needs of nearly 10 million people in urban and rural areas of western Chongqing, and solving the problem of the lack of large high-quality water sources in the Chengdu-Chongqing economic circle.

Project schematic diagram (Jiangjin section)

Aerial photo of Shijiawan Pumping Station