On the 29th, the reporter learned from China Railway 12th Bureau Group that a major breakthrough has been made in the construction of the Sanqing Expressway, a key construction project in Yunnan Province. The right tube of the Xishanying Tunnel, the longest tunnel on the entire line, was recently holed through, laying a solid foundation for the entire line to be completed and opened to traffic as scheduled.

The left tube of the Xishanying Tunnel is 6,829 meters long and the right tube is 6,787 meters long. The tunnel is invested in and constructed by China Railway Construction Kunlun Investment Group and undertaken by China Railway 12th Bureau Group. The tunnel is designed with a separated structure and is a major and difficult control project on the entire line, with high technical requirements for water inflow treatment construction and high construction risks.

Facing these difficulties, the project department of China Railway 12th Bureau Group set up a technical research team, adopted advanced technical means, and optimized and innovated a series of construction plans and techniques. Up to now, it has applied for 7 scientific and technological achievements, including "a pipe-roof grouting connection structure for water-rich tunnels" and "research on the top-heading construction technology for large-section tunnels in weak water-rich strata," effectively advancing the project construction.

The Sanqing Expressway starts at Sanbao in Qujing, Yunnan, and ends at Qingshui in Kunming. It consists of the Qujing section and the Kunming section, with a total route length of 128 kilometers. After completion and opening to traffic, it will become a fast corridor from Qujing to Kunming and the central Yunnan industrial cluster area, effectively alleviating the current traffic congestion on the existing Kunming-Qujing Expressway.