Recently, the blind-tunnel excavation at the exit of the Baoyun Tunnel on Section 5 of the Yungui (Yunnan-Guizhou) segment of the Chongqing-Kunming High-Speed Railway, constructed by China Railway 18th Bureau Group, surpassed the 1,000-meter mark.

According to reports, the Baoyun Tunnel on the Chongqing-Kunming High-Speed Railway is located in Huize County, with a total length of 16,797 meters and a design speed of 350 km/h. The area where the tunnel is located features dramatic topographic relief and complex geological structures, with karst development and a fragile ecology; the tunnel body passes through multiple fault fracture zones, and the construction geological conditions are complex, with frequent cross-operation of procedures. Adverse factors include low-gas emission, large deformation of soft rock, bedding-plane collapse, and landslides. The technical requirements for ventilation and drainage are high, and construction management is difficult. It is a key project and a Class II risk tunnel on the entire line.

This breakthrough in excavation at the tunnel exit will provide valuable experience for the subsequent construction of the Baoyun Tunnel and marks that the construction progress of the Chongqing-Kunming High-Speed Railway will be further accelerated.