At 9:58 on April 20, construction of the second extra-long tunnel of the Shenyang-Baihe High-Speed Railway undertaken by China Railway 23rd Bureau Group Co., Ltd. reached a new milestone: the 3.714-kilometer section from the Changqing Tunnel entrance to No. 1 inclined shaft was successfully holed through, leaving only 452 meters to achieve the goal of breaking through the tunnel's "last kilometer." This will win valuable time for accelerating the construction progress of this extra-long tunnel and for subsequent ballastless track construction.

　　The Changqing Tunnel in Section TJ-6 of the Jilin portion of the Shenyang-Baihe High-Speed Railway undertaken by China Railway 23rd Bureau is both the second extra-long tunnel of the Shenyang-Baihe High-Speed Railway and one of the controlling works of the entire line. Located in Jiangyuan District, Baishan City, Jilin Province, it has a total length of 11.3 kilometers and is a single-tube double-track tunnel with a maximum burial depth of 320 meters. It includes two inclined shafts and two evacuation passages.

　　In the three years since construction began, under the guidance and full support of the construction unit, the contractor has continuously strengthened construction organization and made every effort to promote high-standard construction, high-efficiency advancement, and high-quality completion. Following the holing-through of the 4.129-kilometer section from No. 2 inclined shaft to the exit on March 28, another breakthrough was reported on April 20 with the holing-through of the 3.714-kilometer section between the tunnel entrance and No. 1 inclined shaft. It is understood that the entrance-to-No. 1-inclined-shaft section of the Changqing Tunnel holed through this time passes through multiple faults and their influence zones, is located in Class III, IV, and V surrounding rock areas and Class I and II high-risk areas, and has an inclined shaft gradient of 12%, the highest on the entire line; it is also the section of this extra-long tunnel with the most complex geological conditions and the greatest construction difficulty.

　　The Shenyang-Baihe High-Speed Railway Project Department of China Railway 23rd Bureau Group overcame the impact of adverse geological conditions, planned ahead, organized meticulously, and actively carried out technological innovation, optimizing the standardized wet spraying construction method for large-section tunnels of high-speed railways in alpine regions, as well as the tunnel insulation and waterproofing/drainage methods for alpine regions. In domestic tunnel excavation construction, special equipment such as double-boom drill jumbos was used for the first time. At the same time, safety and quality control were strictly enforced, with the three-bench method and bench method adopted for construction, and with a "short, tight, fast, and frequent" mode, strictly achieving "advance detection, advanced pipe roof support, short advance per round, weak disturbance, strong support, rapid sealing, and frequent measurement." At the peak of on-site construction, more than 100 workers were deployed, cycle times were continuously optimized, and work proceeded 24 hours without interruption, with all processes advancing in parallel, ensuring safe, smooth, and on-schedule holing-through. The tunnel is expected to achieve full holing-through before June 30.