On July 18, a resounding blast heralded the completion of the Yuanbaoshan Tunnel on the newly constructed Chengdu-Dazhou-Wanzhou High-Speed Railway. This breakthrough marks the overcoming of another major tunnel engineering challenge in the Nanchong section of the railway.

The Yuanbaoshan Tunnel is situated in Xixing Subdistrict, Jialing District, Nanchong City, spanning 905 meters in length and featuring a minimum burial depth of approximately two meters. It is designed as a single-tube, double-track tunnel. The drifting of the Yuanbaoshan Tunnel began on April 11, 2023, and the full tunnel breakthrough took nearly 16 months.

A relevant person in charge from the Chengdu-Dazhou-Wanzhou High-Speed Railway Project Command of China Railway 12th Bureau Group Co., Ltd. explained that, despite the relatively flat terrain of the Yuanbaoshan Tunnel site in the hilly region of central Sichuan, the construction faced significant challenges due to the low-level stability and classification of surrounding rocks, fragmented rock mass structure, and the rocks' susceptibility to softening when wet, leading to a high risk of cave-ins. In order to ensure the steady progress of the construction project, the excavation of V-grade surrounding rock was carried out using a combination of the three-step temporary cross-bracing method and the three-step core soil reservation method, thus laying the groundwork for the punctual completion of the tunnel and the acceleration of the entire Chengdu-Dazhou-Wanzhou High-Speed Railway project.

The Chengdu-Dazhou-Wanzhou High-Speed Railway constitutes a crucial component of the transportation corridor along the Yangtze River within China's "Eight Vertical and Eight Horizontal" high-speed rail network. Stretching over 400 kilometers and designed to operate at a speed of 350 kilometers per hour, the railway will connect Chengdu, Nanchong, and Dazhou in Sichuan, as well as Wanzhou in Chongqing once completed, paving a vital, swift and convenient route for Sichuan's eastward connectivity.