Development of new deformation-controlled rockbolt: numerical modelling and laboratory verification

To prevent large tunnel deformations caused by rock bursts or squeezing ground conditions, rockbolts need to satisfy both strength capacity and the required deformability. Currently, energy-absorbing rockbolts, such as the cone bolt and the D-bolt, have been successfully used in deep mining to avoid sudden tunnel collapses. This paper proposes a new energy-absorbing rockbolt, referred to as a deformation-controlled rockbolt (DC-bolt). The performance of the proposed DC-bolt was verified by numerical simulations using discontinuous deformation analysis (DDA) and by prototype laboratory tests. As a result, it is concluded that the DC-bolt possesses both high loading capacity and deformation capacity. Additionally, the DC-bolt can limit rock surface movement when it reaches a certain displacement. Thus, it can be a useful tunnel support for tunnels that are to be excavated in squeezing ground conditions.