On January 18, the right tube of Jiangcheng No. 2 Tunnel on the Yunnan Menglü Expressway, constructed by China Railway Construction Engineering Group Co., Ltd., was successfully holed through, marking another breakthrough in the key and difficult control works along the entire line of the Menglü Project Section 7 and achieving a "good start" with the first victory of the project in 2024.

Jiangcheng No. 2 Tunnel is a separated long tunnel, with a right tube totaling 2396.96 m in length, excavated from both ends. The tunnel is a standard two-lane tunnel. The surrounding rock is dominated by quartz sandstone and argillaceous siltstone, strongly to moderately weathered, with thin to medium-thick layered structure, broken rock mass, relatively developed joints and fissures, and strong water-bearing property. Geophysical exploration results indicate that it is mostly a high-resistivity zone; the rock mass has relatively strong water-bearing property. The designed surrounding rock grades are Grade V and Grade IV, and the maximum buried depth of the tunnel is 197.25 meters. The project is highly difficult to construct and carries high safety risks.

To ensure the smooth holing-through of the tunnel, the construction party strictly followed the construction principles of "early forecasting, water control first, pre-reinforcement, weak blasting, short excavation, roof support first, strong support, early sealing, frequent measurement, and rapid lining," planned ahead, exercised scientific management, continuously optimized resource allocation, improved on-site construction organization, and overcame various difficulties encountered during construction such as unfavorable geology and difficult material transportation, ensuring the safe and smooth holing-through of the tunnel.

The Menglü Expressway is about 211 km long, starting from Menglun Town, Mengla County, Xishuangbanna Dai Autonomous Prefecture, passing through Jiangcheng County, Pu'er City, and ending at Lüchun County, Honghe Hani and Yi Autonomous Prefecture. It plays an important role in China's expressway network of "linking the provincial territory, bordering the southwest border, and radiating to both sides of the national gateway."