Core Viewpoint - The successful completion of the shield tunneling section of the Chongqing Caiyuanba Yangtze River Tunnel marks a significant milestone for the Yuxia High-Speed Railway, which is a key project in the high-speed rail network of China [1][3]. Group 1: Project Details - The Chongqing Caiyuanba Yangtze River Tunnel is the first high-speed rail tunnel crossing the Yangtze River in the upper reaches, with a total length of 11,942 meters [1][3]. - The tunnel features a single-hole double-track design, starting from Chongqing Railway Station and passing under various infrastructures, including municipal roads and the main channel of the Yangtze River [3][5]. - The shield tunneling section of the tunnel is 3,845 meters long, with 1,282 meters crossing the Yangtze River, utilizing the "Yangtze" mud-water balance shield machine with a diameter of 12.66 meters [3][5]. Group 2: Technical Innovations - The construction faced challenges such as high water pressure and complex geological conditions, prompting the development of advanced technical solutions, including a high-precision gas-liquid pressure balance system and a high-pressure flushing system [3][5]. - The technical team from China Railway Second Institute introduced an innovative structural design that combines upper arch cover composite lining with lower side wall anchor retaining wall, addressing assembly challenges for large-diameter shield machines [5]. Group 3: Strategic Importance - The Yuxia High-Speed Railway is an essential part of China's "eight vertical and eight horizontal" high-speed rail network, enhancing connectivity between major cities [5]. - Segments of the Yuxia High-Speed Railway, including the sections from Chongqing East to Changsha and from Ganzhou to Xiamen, are already operational, with further segments under construction to complete the high-speed corridor from Chongqing to Xiamen [5].