On July 21, after 1,380 days of arduous efforts, the double-line breakthrough of the Heimaguang Extra-Long Tunnel, a control project of the Kanglue Expressway built by Gansu Road & Bridge, was successfully achieved.

The construction of the Heimaguang Extra-Long Tunnel required passing through various unfavorable geological structures such as fault fracture zones, large-deformation soft rock sections, and water-rich phyllite sections, posing great construction difficulties and high safety risks. During construction, the maximum crown settlement was 51.6 cm, the maximum single-side peripheral convergence deformation at the haunch was 154.1 cm, and the maximum single-day convergence rate was 13.2 cm. Large deformation of soft rock persisted for 20 months, with the deformed section reaching 1 km, accounting for 20% of the total tunnel length. The intrusion of the initial support due to soft rock deformation led to a arch replacement rate as high as 14%. During construction, 6 relatively large collapses and multiple small collapses occurred, and at the most difficult time for the right line, the monthly advance was only 15.8 meters. To ensure smooth tunneling, the project department comprehensively analyzed the safety risks of tunnel construction, formulated risk prevention and mitigation measures in advance for the problem of broken surrounding rock, carried out in-depth safety technical briefings and risk hazard investigations, and safeguarded safe production with advanced geological forecasting, automatic monitoring and measurement systems, pedestrian-vehicle separation systems, and personnel positioning systems. At the same time, it continuously optimized the construction organization plan, strictly controlled the safety step distance, and always carried out construction according to the principle of "fast excavation, fast support, fast closure," laying a solid foundation for safe and smooth tunnel construction.

The Kanglue Expressway project is one of the key projects in the provincial highway network plan. After completion, it will form a rapid corridor from Kang County to Hanzhong City, Shaanxi Province, effectively enhancing the city's comprehensive transportation capacity for linking east and west and achieving interconnectivity, and is of great significance to accelerating the high-quality economic and social development of Gansu, Shaanxi, and Sichuan provinces.