On July 18, with the sound of an explosion, the Yuanbaoshan Tunnel on the newly built Chengdu-Dazhou-Wanzhou High-Speed Railway (hereinafter referred to as the "Chengda-Wan High-Speed Railway") was officially holed through, marking that another major and difficult tunnel project on the Nanchong section of the Chengda-Wan High-Speed Railway has been overcome.

Yuanbaoshan Tunnel

It is reported that the Yuanbaoshan Tunnel is located in Xixing Subdistrict, Jialing District, Nanchong City, with a total length of 905 meters and a minimum burial depth of about 2 meters. The tunnel consists entirely of Class IV and Class V surrounding rock and is a single-tube double-track tunnel. Starting from April 11, 2023, excavation of the Yuanbaoshan Tunnel began, and the full breakthrough took 16 months.

According to the introduction, although the Yuanbaoshan Tunnel site is located in the hilly area of central Sichuan, where the terrain undulates only slightly, the surrounding rock has poor stability, a relatively low classification, fractured rock mass, and is prone to softening upon contact with water and easy collapse, making construction relatively difficult. To ensure the steady progress of the project, the project department dynamically adjusted the construction plan. For Class V surrounding rock, the three-bench temporary cross-bracing method and the three-bench reserved core soil method were adopted, laying the foundation for the tunnel's completion on schedule and accelerating the construction of the entire Chengda-Wan High-Speed Railway.

The Chengda-Wan High-Speed Railway is an important component of the Yangtze River corridor of China's "Eight Vertical and Eight Horizontal" high-speed railway network. It has a total length of more than 400 kilometers and a designed speed of 350 kilometers per hour. Once completed, it will connect Chengdu, Nanchong, and Dazhou in Sichuan with Wanzhou in Chongqing, forming an important fast and convenient corridor for Sichuan to exit eastward.