On July 21, after 1,380 days of arduous efforts, the Heimaguan Extra-Long Tunnel, a controlling project of the Kangxian-Lueyang Expressway built by Gansu Road & Bridge Construction Group, was successfully holed through on both tubes.

The construction of the Heimaguan Extra-Long Tunnel required passing through various unfavorable geological structures, including fault fracture zones, large-deformation soft rock sections, and water-rich phyllite sections, posing great construction difficulty and high safety risks. During construction, the maximum crown settlement reached 51.6 cm, the maximum single-side peripheral convergence deformation at the haunch reached 154.1 cm, and the maximum single-day convergence rate reached 13.2 cm. Large deformation of soft rock persisted for 20 months, with the deformed section extending 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 major collapses and multiple minor collapses occurred, and at the most difficult time on the right tube, the monthly advance was only 15.8 meters. To ensure smooth tunneling, the contractor comprehensively analyzed the safety risks of tunnel construction, formulated risk prevention and mitigation measures in advance targeting the fractured surrounding rock, and carried out in-depth safety technical briefings and risk hazard inspections, safeguarding safe production with advanced geological forecasting, automatic monitoring and measurement systems, pedestrian-vehicle separation systems, and personnel positioning systems. At the same time, the construction organization plan was continuously optimized, safety step distances were strictly controlled, and construction was always carried out according to the principle of "rapid excavation, rapid support, rapid closure," laying a solid foundation for safe and smooth tunnel construction.

The Kangxian-Lueyang Expressway project is one of the key projects in Gansu Province's provincial road network plan. Once completed, it will form a rapid corridor from Kangxian to Hanzhong City, Shaanxi Province, effectively enhancing Longnan City's comprehensive transportation capacity as a link between east and west and its interconnectivity, and is of great significance to accelerating the high-quality economic and social development of Gansu, Shaanxi, and Sichuan provinces.