Computer modeling can be used to explore insights into the effect of rockbolt intersecting joints in rock masses and to estimate the effectiveness of the rock reinforcement system. In this paper, the fully grouted rockbolts are modeled within the frame work of the two-dimensional discontinuous deformation analysis (2D-DDA). In DDA, the rock block is modeled by elastic, perfect plastic behavior, while the rockbolt material is modeled in the elastic, followed by the linear strain-hardening behavior. In addition, the shear force generated by slippage along the interface is assumed to have a linear relationship with respect to the relative slipping distance between the rockbolt and the rock. After the unit shear force reaches to the critical value, the frictional debounding will occur following the assumed interface mechanical behavior. Three pullout tests are simulated to predict fully grouted rockbolt behaviors in different kinds of rock masses. The results show that in hard rock, the mechanical interlock between the rockbolt and the rock dominants the fully grouted rockbolt behavior However, when the rockbolt intersects joints in soft rock, the interface debounding is constrained to a small area. In that case, the interface behavior would be much less effective. It can be seen that the reinforcement efficiency of fully grouted rockbolt is affected by the surrounding rock mass.

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