It was recently learned that the Jinping Mountain Tunnel, a key project controlling the girder-erection schedule of the Jinan-Laiwu High-Speed Railway, has broken through, clearing the last bottleneck for girder erection in civil works Section 3 of the railway.

The Jinping Mountain Tunnel is 2,515 meters long and is a single-tube, double-track tunnel. According to the construction plan, the 108 precast box girders for four bridges—the Zhangqiu South Extra-Large Bridge over the Beijing-Shanghai Expressway, the Zhangqiu South Extra-Large Bridge over S242, the Xitianguang Village Extra-Large Bridge, and the Tianguang Village Bridge—must pass through this tunnel before they can be erected.

Because the tunnel passes through a denuded hilly area, the geological conditions are complex and the surrounding rock grade varies greatly, making construction difficult and risky, and the schedule extremely tight. To ensure the tunnel broke through on time without affecting box girder erection, the construction unit planned ahead, worked to a reversed schedule, and optimized the plan, adding an open-cut section to enable simultaneous construction on four working faces, greatly accelerating the excavation progress.

During construction, the construction unit followed the principles of "advance pipe forepoling, strict grouting, short excavation, rapid sealing, strong support, and frequent measurement," strictly controlled the safety step distance, and in particular adopted the "micro-bench method" of construction, which greatly improved the progress and safety quality of Grade V surrounding rock construction. At the same time, by optimizing the construction sequence and adding measures such as a second-lining trolley, the construction progress was greatly accelerated and the construction task was successfully completed.

Since the beginning of this year, the Jinan-Laiwu High-Speed Railway has密集ly reached multiple project milestones, including the breakthrough of several tunnels such as Lanyu, Shimoding, Baijiazhuang, and Majiazhuang; and the closure of multiple continuous girders, including the swivel continuous girder of the extra-large bridge over the Wat-Ri Railway, the Shawancun Bridge, the extra-large bridge at Ganggou Station over Century Avenue, the Xiaoyi Reservoir Extra-Large Bridge over the Beijing-Shanghai Expressway, and the Zhangqiu South Bridge over the Beijing-Shanghai Expressway.