On September 19, the Zimuyan Extra-Long Tunnel of the Wulong–Daozhen Expressway ("Wudao Expressway"), constructed by the Road & Bridge Group under Guizhou Transportation Construction Group, successfully achieved double-tube breakthrough, laying a solid foundation for the full opening of the Wudao Expressway.

The Zimuyan Extra-Long Tunnel of the Wudao Expressway successfully achieved double-tube breakthrough.

It is understood that the Wudao Expressway starts on the east side of Wulong District in Chongqing and ends in Daozhen County, Guizhou Province, with a total length of approximately 69 km, of which the Guizhou section is about 38 km. Once completed and opened to traffic, the driving time from Daozhen to Wulong will be shortened from 2.5 hours to 0.5 hours.

Portal of the right tube of the Zimuyan Extra-Long Tunnel.

The Zimuyan Extra-Long Tunnel is the largest controlling project and a major difficult project of the Wudao Expressway. The tunnel starts at the Chongqing–Guizhou border, in the slope zone where the Dalou Mountains' extension transitions toward the Sichuan Basin. It is a separated extra-long tunnel with a total length of 7,407 meters, divided into the Guizhou section and the Chongqing section. The Guizhou section has a left tube of 5,348 meters and a right tube of 5,393 meters, making it the longest reverse-slope tunnel under construction in Guizhou for single-end excavation.

Portal of the Zimuyan Tunnel.

The Zimuyan Extra-Long Tunnel has complex geological conditions. The alignment passes through 2 synclines and 3 fault fracture zones, and during construction more than 40 karst caves of various sizes were encountered, including karst mud inrushes and large karst chambers, making construction extremely difficult. During construction, the project team adhered to the principles of advanced construction technology, feasible construction schemes, scientific and reasonable construction organization, high quality, safety and efficiency on schedule, and leaving no future troubles. Through a series of technologies such as smooth blasting, 3D laser scanning, polymer telescopic end formwork for secondary lining, mobile formwork trolley construction for cable trenches, tunnel cross-passage lining trolley construction, and tunnel informatization management, they safeguarded the quality control of the tunnel.

Rendering of the Zimuyan Tunnel.

At the same time, to better advance the project construction, the Wudao project team actively promoted the integration of industry and research, worked closely with research institutions such as Southwest Jiaotong University, continuously optimized construction techniques and improved technical levels, and carried out a series of research projects such as "Research and Application of Key Technologies for Low-Carbon Green Construction of Extra-Long Highway Tunnels under Complex Geological and Special Environmental Conditions," providing corresponding research results and pioneering experience for the construction of "extra-long" major and difficult tunnels in the province in the future.

It is reported that after the Wudao Expressway is completed and opened to traffic, it will be of great significance for northern Guizhou to accelerate its integration into the Chengdu–Chongqing Economic Zone, support the process of regional industrialization and new urbanization, and promote the rapid development of regional tourism and rural revitalization. Next, the project team will accelerate safe and efficient project construction, promote high-quality project development, and provide a strong guarantee for the smooth opening of the entire Wudao Expressway.