Rock bolt

It transfers load from the unstable exterior to the confined (and much stronger) interior of the rock mass.

Rock bolts were applied to civil tunneling support in the U.S. 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-meter-long expanding anchor rock bolts while working on the Snowy Mountains Scheme.

[2] Rock bolts are an essential component of the New Austrian Tunneling method.

As shown in the photo, rock bolts may be used to support wire mesh, but this is usually a small part of their function.