The progress has been updated again! The right line of the Yuanbaoshan Extra-long Tunnel was successfully connected

On January 17th, the right line of the Yuanbaoshan Long Tunnel of the XJ19 contract section of the Yichang-Panzhihua Expressway's Yichang-Jinchuan section, which was constructed by the Road and Aviation Company, was successfully connected. This marks a breakthrough in the project's construction and lays a solid foundation for the smooth completion and opening of the Yichang-Panzhihua Expressway's Yichang-Jinchuan section.

The Yuanbaoshan Long Tunnel is located 200 to 300 meters east of the Ebian-Jinyang Fault, nearly parallel in layout. A large section of the tunnel body is within the fault fracture zone or the fault influence zone. The left line of the tunnel is 5,747 meters long and the right line is 5,739 meters long. Among them, the proportion of V-grade surrounding rock is as high as 75%, and the maximum daily average water inflow is 45,694 cubic meters. The geological conditions of the tunnel are extremely complex, the stability of the surrounding rock is very low, the construction period is long, and the organization difficulty is high. It is one of the key control projects with extremely high construction difficulty and high safety risks in the Yijin section.

Facing challenges, the project team took multiple measures and rose to the challenge. In response to the tunnel excavation crossing fault zones and large deformation of soft rock, the project team focused on the target tasks, clarified responsibilities, reversed the construction schedule, established a technical breakthrough team and a youth assault team, and conducted on-site supervision throughout the key procedures. By observing the rock properties of the tunnel surrounding rock, they promptly adjusted the support parameters and continuously optimized the construction plan and organization. The first is to actively promote intelligent construction of tunnels. We have successively introduced intelligent mechanical equipment such as intelligent arch frame trolleys, two-arm rock drilling trolleys, large wet shotcrete machines, and intelligent secondary lining trolleys, effectively solving technical problems encountered in tunnel excavation, such as the gradual softening of surrounding rock, the decline in overall stability, the collapse of tunnel arch roofs, and sudden mud and water gushing. The second is to vigorously implement smooth blasting. Strictly adhering to the construction principles of "pipe advance, strict grouting, short advance, weak blasting, less disturbance, frequent measurement, and tight closure", technical breakthroughs were made on blasting parameters, drilling procedures, and improving the acceptance rate of smooth blasting in the soft surrounding rock of the tunnel based on the surrounding rock conditions at the tunnel face. This effectively controlled the disturbance of the surrounding rock and over-excavation and under-excavation, ensuring the flatness and stability of the tunnel excavation face. Third, strictly implement the monitoring and measurement system as well as the advanced geological prediction system. The surrounding rock conditions ahead are detected by means of TSP203, geological radar method, infrared detection method, geological horizontal drilling and other technical means, so as to adopt different measures and correct construction methods. Fourth, strictly implement the tunnel safety management system. By setting up access control, video surveillance and other security management systems, the progress of tunnel construction is monitored in real time and dynamically in all aspects, effectively ensuring the safety and reliability of the tunnel excavation process. The fifth is to comprehensively carry out innovation and efficiency creation. Based on the actual situation of the Yuanbaoshan Extra-long Tunnel, the project team has intensified efforts in scientific and technological innovation. They have successively developed one leading domestic construction method, applied for one invention patent and two utility model patents, won two first prizes of provincial QC achievements, and published two professional papers.

It is expected that by the end of 2025, the Yuanbaoshan Extra-long Tunnel will be fully connected in both directions. After the project is completed, it will be of great significance for promoting the development of the Yi areas in Liangshan, connecting with the Yunnan region, facilitating the integrated development of "transportation + agriculture and tourism", promoting ethnic unity and progress, consolidating the achievements of poverty alleviation, assisting in resource development and rural revitalization, and improving the quality of life of residents.