Soil nailing is used as a remedial measure to treat unstable soil slopes.  The technique involves the insertion of relatively slender reinforcing elements into the slope – these ca be standard solid reinforcing bars (rebar) or hollow-system bars are also available. Solid bars are usually installed into pre-drilled holes and then grouted into place using a separate grout line, whereas hollow bars may be drilled and grouted simultaneously by the use of a sacrificial drill bit and by pumping grout down the hollow bar as drilling progresses.