Numerical Modeling of Fully Grouted Rockbolts Reaching Free-End Slip

In this study, numerical simulation was conducted to model the behavior of rockbolts with free-end slip in tension. A nonlinear bond–slip relationship was input to the numerical model to represent the interaction mechanism of the interface between rockbolt and grout. The results of the model were validated against laboratory tests. The numerical model matched the experimental results in terms of load–displacement relationship, rockbolt strain distribution, and interfacial shear-stress distribution. This paper indicates that (1) the rockbolt element in the numerical model is capable of describing the strain-softening behavior of the rockbolt–grout interface; and (2) the pullout tests of rockbolts with free-end slip can be used to derive the bond–slip relationship, and thus provide insights into the mechanical behavior of rockbolts with free-end slip.