High Gas Tunnel through the first Tunnel of Chengdu Metro

Chengdu Rail Transit Line 18 starts at South Railway Station and passes through Gaoxin, Huayang and Tianfu New District to cross Longquan Mountain to the new airport. It connects Chengdu City, Tianfu New District and Tianfu International Airport. It is a composite function line integrating the functions of the Market Express Line and the Airport Line. After completion, it will also greatly ease the pressure on Chengdu's north-south passenger flow and provide passengers with more convenient public transportation service.

As the new airport express line, Line 18 is designed not only to meet the passenger flow needs of Tianfu International Airport far from the central city, but also to provide a strong guarantee for efficient and punctual passenger flow at the airport, and to meet the passenger flow needs of Tianfu Avenue. To ease the traffic congestion of the urban development axis in the North and South, the line has put forward three major characteristics of "first speed, first tunnel, and first scale" in its design. Among them, the first speed: China plans to build the first subway line with a design speed of 140 kilometers per hour; The first tunnel: The total length of the No. 1 tunnel in Longquan Mountain is 9.7 kilometers. It is the longest rail transit(subway) mountain high gas tunnel under construction in China; The first scale: is the largest rail transit project implemented by the National PPP model.

As the first rail transit project to cross the high gas strata in the country, Line 18 has a total length of approximately 66.71 kilometers. The key difficulty in construction is to cross Longquan Mountain and open a 9.7-kilometer mountain high gas tunnel.

Before entering the tunnel, the construction staff must touch the electrostatic receiver and absorb the static electricity from the body. The equipment entering the construction site is also explosion-proof products. The excavators and loaders entering the tunnel have been professionally reformed and explosion-proof equipment has been installed. In order to overcome this 2 km high gas tunnel, the participating units also adopted the "simultaneous import and export excavation" method and the "light blasting" process, and actively carried out engineering and technological innovation. For example, negative pressure belt mold grouting, longitudinal stop water belt fixture, vertical arch waterproof plate laying on the three-wire upper wall system, and also set up a wind tube cloth bracket to solve the phenomenon of the wind tube cloth is not straight, fall and so on. Three of these innovative crafts laws have been patented by the State.

At present, the main structure of the entire station on the 18th phase has been capped. According to the plan, it is expected to open to traffic in 2020.