On June 22, the right tube of the Jigongshan Tunnel on the Shenzhen Banyin Corridor, constructed by the Guangzhou Company of China Railway Sixth Group, was successfully holed through, marking major progress and a breakthrough in the project.

The Jigongshan Tunnel is about 2.4 km long and is built to the standard of an urban Class I arterial road. The main works include a 40 m (single-track) subgrade, one 4,800 m tunnel (single-track), and a newly added inclined shaft. The ground elevation in the tunnel area ranges from 147.582 to 349.22 m, with a maximum burial depth of 235.705 m. The portal adopts an end-wall type portal, excavation is by drill-and-blast, and composite lining is used. The surrounding rock is mainly Grade III and IV, accounting for 79% of the total tunnel length. The geological conditions in this section are complex, dominated by migmatitic granite; the rock mass tends to expand and disintegrate after being exposed to air and absorbing moisture. The comprehensive risk rating is Grade III, making it a high-risk tunnel. During construction, the Shenzhen Banyin project team of the Guangzhou Company overcame difficulties and took multiple measures to ensure the smooth holing-through of the tunnel. First, it actively communicated with all parties and held several expert review meetings to continuously optimize and improve the construction plan. Second, it strictly guided on-site construction in accordance with the NATM principles of “advance pipe forepoling, strict grouting, short advance, weak blasting, early closure, and frequent measurement.” Third, it carried out monitoring and measurement and advanced geological prediction work in earnest to keep timely track of the geological conditions ahead of the tunnel face and the deformation of the surrounding rock. Fourth, it scientifically arranged the construction organization plan, rationally allocated resources, and adhered to the safety philosophy of “zero injury, zero accident, zero loss” to ensure the safety, quality, and progress of tunnel construction.

The successful holing-through of the right tube of the Jigongshan Tunnel on the Shenzhen Banyin Corridor demonstrates the Guangzhou Company's firm determination in carrying out the labor competition of “work hard in the second quarter, overcome difficulties and ensure the goal,” and lays a solid foundation for realizing the plan to open the Banyin Corridor to traffic by the end of the year.