Construction site of the Saimamen Tunnel on the Kangyu section of the Xi'an-Chongqing High-Speed Railway

At around 10 a.m. on August 26, with the final excavation, the Saimamen Tunnel on the Ankang-Chongqing section (hereinafter referred to as the Kangyu section) of the Xi'an-Chongqing High-Speed Railway was successfully holed through. This is the first tunnel to be holed through within Chongqing's territory on the Kangyu section of the Xi'an-Chongqing High-Speed Railway, marking that tunnel construction along the entire line has entered a critical stage.

The Xi'an-Chongqing High-Speed Railway is an important component of the Beijing-Kunming corridor and the Baotou (Yinchuan)-Haikou corridor of China's "Eight Vertical and Eight Horizontal" high-speed railway network, and holds a very important position in the road network. The main line of the Kangyu section of the Xi'an-Chongqing High-Speed Railway has a total length of 478 kilometers. Starting from Ankang West Station, it passes through Ankang City in Shaanxi Province, Chengkou County in Chongqing, Dazhou City and Guangan City in Sichuan Province, and Hechuan District and Beibei District in Chongqing, before being introduced into Chongqing West Station of the Chongqing hub.

The Saimamen Tunnel is located within Hechuan District, Chongqing, with a total length of 850 meters. It is a single-tube double-track tunnel designed for a speed of 350 kilometers per hour. The tunnel area features hilly terrain, with relatively large ground undulations and a complex surrounding environment. The adverse geological conditions of the project mainly include asymmetrical loading and shallow cover, dangerous rockfall, goaf areas, and harmful gases such as methane. Grade IV and V surrounding rock account for as much as 96.5% of the entire tunnel, resulting in high construction safety risks.

To this end, the builders optimized the construction plan, innovated processes and methods, and used technical means such as advanced geological forecasting, monitoring and measurement, and an information-based platform for advanced support. Through full-process monitoring of construction, they effectively ensured tunnel construction safety and achieved a smooth holing-through after 425 days and nights.

After the Xi'an-Chongqing High-Speed Railway is completed and opened to traffic, the project will connect with the already completed and operating Chengdu-Chongqing High-Speed Railway and Zhengzhou-Chongqing High-Speed Railway, as well as multiple lines under construction, including the Chongqing-Kunming High-Speed Railway, Xi'an-Yan'an High-Speed Railway, and Xi'an-Shiyan High-Speed Railway. It will further improve the road network structure in the central and western regions, greatly facilitate travel for the people along the line, and be of great significance for consolidating and expanding the achievements of poverty alleviation, comprehensively advancing rural revitalization, promoting urban-rural integration and coordinated regional development, and shaping a new pattern of large-scale development of the western region.