What machinery is usually used to dig tunnels?

The professional name is shield machine.

1997, China introduced two shield machines from Germany for the first time to excavate the Qinling tunnel of Xikang Railway. At that time, the price of an imported shield machine reached 300 million yuan. Until 2008, China's shield machines were heavily imported. The foreign monopoly technology does not allow the Chinese to participate in the maintenance, and the man-hours required for the maintenance are completely dependent on the foreign side, which seriously affects the progress of the Chinese project.

In order to get rid of the predicament, in August 2002, "China Railway Equipment" set up a research and development team consisting of 18 people. After six years of technical research, China's first composite shield machine with independent intellectual property rights was successfully rolled off the production line in 2008, and it was first applied to Tianjin subway project, realizing the transformation from "using shield to building shield".