On Sept. 16, excavation of both tubes of the Yanyuan Tunnel, the longest tunnel along the G7611 Xichang-Shangri-La Expressway (Sichuan section), has surpassed the halfway mark, laying a solid foundation for the full opening of the expressway.

Located in Beishan Village, Liangshan Yi Autonomous Prefecture, at an altitude of approximately 2,500 meters, the Yanyuan Tunnel spans 14.15 kilometers with a maximum burial depth of 1,090 meters. It is the longest tunnel on the entire Xichang-Shangri-La Expressway, the fourth-longest highway tunnel currently under construction in China, and a critical control project linking Xichang to Yanyuan.

Construction Inside Tunnel

Situated in the core area of the Hengduan Mountains, the tunnel traverses complex adverse geological conditions, facing multiple risks including significant surrounding rock deformation, water inrush, and rock bursts. The combination of high-altitude and frigid climate with complex geological structures creates intertwined risks, posing immense technical challenges to construction.

Tunnel Exit Portal

Leveraging mechanized equipment, the construction team established a seamless mechanized workflow integrating "excavation, support, mucking, and lining", increasing the average daily excavation progress by 40% compared to traditional methods.

Meanwhile, a three-in-one risk prevention system featuring "advanced geological forecasting, real-time monitoring and measurement, and dynamic design optimization" was implemented, significantly reducing manual labor intensity and safety risks. Regarding spoil disposal, the team utilized forward BIM design to optimize route alignment and construction organization, processing part of the tunnel muck into subgrade fill material. This approach maximized protection of the Xiaogaoshan natural environment, achieving coordinated advancement of engineering construction and ecological conservation.

Route Schematic Diagram

Invested and constructed by Shudao Group, the Xichang-Shangri-La Expressway has a total length of 233.13 kilometers, with bridges and tunnels accounting for 73.4% of the route. Built to a dual-direction, four-lane expressway standard with a design speed of 80 km/h, the project has an estimated total investment of approximately 58.7 billion yuan and is expected to open to traffic in its entirety by 2029.

Upon completion, travel time from Xichang to Yanyuan will be reduced from three hours to less than one hour, while travel time to Lugu Lake will drop from five hours to under two hours. A self-drive trip from Chengdu to Lugu Lake will take just seven hours nonstop, saving two and a half hours compared to current travel times.

【本篇文字部分内容由 AI 辅助写作，特此声明。Please note: the text in this article was created with the help of AI.】