On the morning of October 16, after approximately 22 months of challenging construction efforts, the Huangjiashan Tunnel along the Chengdu-Dazhou-Wanzhou High-Speed Railway (hereafter referred to as the “Chengda-Wan Expressway”) successfully broke through. This milestone marks the beginning of a critical phase in tunnel construction for the entire project.
The Chengda-Wan High-Speed Railway is a vital part of China’s “eight vertical and eight horizontal” high-speed rail network, particularly along the river corridor. Spanning 477 kilometers, the line starts at the Tianfu Station in Chengdu, Sichuan Province, passes through several cities including Ziyang, Suining, Nanchong, Dazhou, and the Kaizhou and Wanzhou districts of Chongqing, ultimately connecting to the existing Zhengzhou-Chongqing High-Speed Railway at the Wanzhou North Station. The design speed for the railway is set at 350 kilometers per hour.
The Huangjiashan Tunnel, located in Nanchong City, Sichuan Province, is a single-tube dual-track tunnel with a total length of 3,106 meters and a maximum depth of 125 meters. It is considered a pivotal engineering challenge due to its complex construction conditions, including crossing beneath the under-construction Jiufengshan Tunnel of the Nantuo Expressway and the G318 National Highway, as well as various pipelines and channels. Rough geological conditions are prevalent, with 90% of the surrounding rock being classified as Grades IV and V, which poses significant construction difficulties and safety risks. Yang Hua, the chief engineer at the China Railway 12th Bureau for the Chengda-Wan project, noted, “The Huangjiashan Tunnel is the longest and most complex tunnel in the Chengdu to Yingxian West section.”
In order to minimize the impact of blasting on existing roads and pipelines and to manage risks such as collapses, mechanical excavation methods were predominantly employed, limiting the blasting scope. Approximately 300 meters of the tunnel were excavated using machinery, which has somewhat slowed progress. Additionally, to ensure timely completion of the tunnel construction, the team utilized an “one tunnel, nine lines” strategy, equipping each work area within the tunnel with various mechanized devices, including multifunctional work platforms and arch installation vehicles. This approach has led to a 30% increase in work efficiency while allowing for more than a 20% reduction in workforce.
The Chengda-Wan High-Speed Railway is being constructed in two segments: from Chengdu East to Yingxian West and from Yingxian West to Wanzhou North. The Huangjiashan Tunnel is the longest in the Chengying section, and its completion was achieved two months ahead of schedule. To continuously monitor the gas concentration within the tunnel, the project team has installed an advanced automated gas monitoring and alarm system, enhancing safety measures significantly. Currently, of the 133 tunnels along the Chengda-Wan high-speed railway, 79 have been successfully completed.
Upon completion, the Chengda-Wan High-Speed Railway will provide a convenient passenger transport corridor directly linking Chengdu to the Central Plains and the Beijing-Tianjin-Hebei region, greatly facilitating travel for local residents and playing an important role in promoting the economic and social development of the areas along the route.
