On January 17, the first ultra-long tunnel on China's Sichuan-Tibet Railway—the Sangzhuling Tunnel—officially broke through. The tunnel is 16.449 kilometers long, with a maximum rock temperature of 89.9°C, the highest ever encountered in Chinese railway tunnel construction.
The Sichuan-Tibet Railway is one of the five railways for 'the heavenly road into Tibet.' The Lhasa-Nyingchi section connects Lhasa and Nyingchi and will be the first electrified railway in Tibet. This section has 47 tunnels, with a total bridge-tunnel length of 301 kilometers, accounting for 75%.
The Sangzhuling Tunnel is a very important controlling project on the Sichuan-Tibet Railway, located in the Sangjia Canyon area of Shannan City, Tibet. Construction began in December 2014. After 1,125 days of continuous work by more than 1,200 builders, overcoming challenges such as high rock temperature and strong rockbursts, the tunnel was finally completed.
The maximum rock temperature inside the tunnel reaches 89.9°C, and the maximum ambient temperature in the tunnel reaches 56°C. Due to the high temperature, workers cannot work continuously for more than 2 hours in the operation area. To solve the high rock temperature problem, Zhu Xuren, project manager of the Sangzhuling Tunnel for China Railway No.5 Engineering Group, introduced construction measures including installing relay fans to enhance ventilation, installing automatic sprinkler systems for water spraying, and placing ice blocks inside the tunnel.
Li Chuanhai, captain of the Sangzhuling Tunnel team of China Railway No.5 Engineering Group, said that the rockburst area in the tunnel is about 9.5 kilometers long, including a strong rockburst area of 1.5 kilometers; more than 16,000 rockbursts occurred during construction. The construction team used expansion-shell anchor bolts to lock the rock mass and high-pressure water spraying to reduce rock surface temperature and release stress, ensuring construction safety.
It is reported that the Sangzhuling Tunnel has an extremely deep burial depth. Burial depth refers to the depth from the mountain top to the tunnel; over 1,000 meters is considered ultra-deep, making construction difficult. The Sangzhuling Tunnel has a burial depth of 1,347 meters.
Wu Dengfeng, technical supervisor for the exit direction of the Sangzhuling Tunnel, introduced that emergency rescue stations are set up at the exit and entrance directions to ensure the safety of personnel and vehicles. The rescue station at the exit is a three-track passing station, and at the entrance is a double-track passing station. The exit direction of the Sangzhuling Tunnel will connect to a river-crossing bridge.