At 9:00 a.m. on October 27, after 34 months of construction, the right tube of the 3,517-meter Lishi Extra-Long Tunnel, built by the Yuchu Project of China Railway No.2 Engineering Group Co., Ltd. First Company under Contract Section TJ-11, was safely and successfully holed through.

It is reported that Lishi Tunnel is located in Tongchang Township, Yimen County, Yuxi City, Yunnan Province. Lishi Tunnel is a separated four-lane extra-long tunnel, with the left tube 3,535 m long and the right tube 3,517 m long. The left tube runs from mileage ZK95+275 to ZK98+810, including 455 m of Grade V surrounding rock, accounting for 13%, and 3,080 m of Grade IV surrounding rock, accounting for 87%. The right tube runs from mileage YK95+293 to YK98+810, including 451 m of Grade V surrounding rock, accounting for 13%, and 3,066 m of Grade IV surrounding rock, accounting for 87%. There are 5 pedestrian cross passages, 4 vehicular cross passages and 8 emergency parking bays, totaling 400 m. The design speed is 100 km/h, the clearance height of the construction limit is 5 m, and the maximum buried depth is 460 m.

The reporter learned that the tunnel has poor geological conditions, and the broken rock mass is highly prone to local collapse. The project also faced many difficulties, including the need to transport materials over mountains and a tight construction schedule. Since construction started in January 2019, the project department has adopted a safe construction plan featuring advance reinforcement, short advance, rapid sealing and frequent measurement, and has optimized the construction organization to reduce the cycle time of each process. More than 600 construction workers overcame numerous difficulties and worked day and night. After 34 months, they laid the foundation for achieving the goal of opening the entire line to traffic by the end of 2021. At the same time, during construction, the project department actively innovated, and four devices developed in-house, including the "adjusting device for steel arch installation in tunnel construction", won national invention patents.

The Yuchu Expressway is the Yuxi-Chuxiong section of the Mile-Chuxiong Expressway of Highway G8012 and also a component of the outer ring of the Central Yunnan urban economic circle. Its main line is 190.6 km long, with a design speed of 100 km/h and an estimated project investment of 34.987 billion yuan. The route starts at Duoyishu Village, Yanhe Town, Yuxi City, intersects with the Kunming-Mohan Expressway and connects to the Mile-Yuxi Expressway under construction. It ends at Daba Village, Chuxiong City, intersects with the Hangzhou-Ruili Expressway and connects to the starting point of the Chuxiong-Dayao Expressway. A total of 15 interchanges will be built along the line. Once completed, it will open a fast corridor from Yuxi to Chuxiong, realize interconnection among Yuxi, Chuxiong and surrounding cities and counties, and play an important role in promoting economic development in Central Yunnan.

The breakthrough of Lishi Tunnel will accelerate the overall construction progress of Contract Section TJ-11 and lay a solid foundation for the early opening of the Yuchu Expressway.