The kiruna bolt is a rock reinforcement element comprised of a smooth steel bar with a number of deformed sections that act as anchor points along its length. The collar end of the D-Bolt® is threaded and is designed to be used with a face plate, spherical washer and a nut that fastens the bolt. The bolt is fully encapsulated in a borehole, but it is only constrained to the grout or resin along the anchor points. This allows the smooth sections of the bolt, between the anchor locations, to deform without constraints and absorb energy as the rock mass dilates.