9.4.1 Steel reinforcement

Steel reinforcement members in the form of rock bolts, cable bolts, resin-grouted thread bars, or rock dowels are used to tie the rock mass together to increase its stability. Whereas rock bolts are commonly used to reinforce the surface or near-surface rock of the excavation, rock anchors are used for supporting deep seated instability modes in which sliding or separation on a discontinuity is possible.

Steel reinforcement members can be either active or passive at the time of installation. An active member is one that starts interacting immediately upon installation while a passive member does not play a role in ground support until the rock mass moves and subsequently loads the fixture. The main advantage of the active system over the passive system is that no movement has to occur before the active system develops its full capacity. Thus, deformation and possible tension cracking of the slope are minimized. Three common types of ground inclusions are ground anchors, soil nails and rock bolts.