Rock bolt
（重定向自Rockbolt）
A rock bolt is a long anchor bolt, for stabilizing rock excavations, which may be used in tunnels or rock cuts. It transfers load from the unstable exterior, to the confined (and much stronger) interior of the rock mass.
Rock bolts were first used in mining starting in the 1890s, with systematic use documented at the St Joseph Lead Mine in the US in the 1920s. Rock bolts were applied to civil tunneling support in the US and in Australia, starting in the late 1940s. Rock bolts were used and further developed, starting in 1947, by Australian engineers who began experimenting with four metre long expanding anchor rock bolts while working on the Snowy Mountains Scheme.