What is the longest tunnel in China?

The longest tunnel in China is the Zhong Nanshan Highway Tunnel in Qinling Mountain, Shaanxi Province.

Zhong Nanshan Highway Tunnel in Qinling Mountain, Shaanxi Province is the second longest highway tunnel in the world at present, and it can cross Qinling Mountain in 15 minutes.

Qinling Zhongnanshan Tunnel is located in Xi 'an-Zhashui section of the national trunk line from Arun Banner in Inner Mongolia to Beihai in Guangxi, and crosses the Qinling Mountains between Qingcha and Yingpan. The tunnel entrance is located in Qingcha Village, Shibanyu Township, Chang 'an County, Shaanxi Province, and the exit is located in Xiaoyu Street Village, Yingpan Town, Zhashui County, Shaanxi Province, with a total length of 18.4 km. The road grade is designed as expressway, and the safety grade is the first.

The pavement in the tunnel is cement concrete pavement. Combined with geological conditions, the tunnel lining is designed as a composite lining, except for the entrance and exit ⅱ surrounding rock section and ceiling fan section. Tunnel operation ventilation is provided with three vertical shafts, and longitudinal ventilation is performed in sections.

Brief introduction of tunnel

A tunnel is a building built underground, underwater or in the mountains, laying a railway or building a highway for the passage of motor vehicles. According to the location, it can be divided into three categories: mountain tunnels, underwater tunnels and urban tunnels.

In order to shorten the distance, avoid the big ramp, and cross under the mountain or hill, it is called a mountain tunnel; An underwater tunnel that passes under a river or seabed in order to cross a river or strait is called an underwater tunnel. In order to meet the needs of railway crossing big cities, it is called urban tunnel. Among these three types of tunnels, the mountain tunnel is the most built.