Influence of rock bolt reinforcement on shear behaviour of a nonpersistent joint plane

The impact of rock bolts on the mechanical behavior of nonpersistent joints, including the intricate interactions between the joints, rock bridges, and rock bolts, has received limited investigation despite their effectiveness in reinforcing rock mass discontinuities. In order to tackle this issue, a variety of normal stresses were applied during direct shear tests conducted on artificial rock-like specimens with nonpersistent joints, both bolted and unbolted. Meanwhile, to measure the deformation in the rock bridge and joint plane region, a set of strain gauges were implemented. The findings indicated that the local shear deformation-shear displacement curves, whether with or without rock bolts, can be categorized into five distinct stages. Application of the rock bolts on the nonpersistent joint plane resulted in making the following two important statements: (a) The rock bolts delay the shear stress transmission along the joint plane from the joint parts to the rock bridge area; (b) The rock bolts limit the dilatancy occurring in both the joint parts and at the rock bridge area. Furthermore, the shear displacement of the bolted nonpersistent joint specimen at the peak shear strength was found to be greater than that of the unbolted nonpersistent joint specimen indicating protection of the rock bridge by the rock bolts. Whether bolted or unbolted, the stiffness values seem to be the same for the nonpersistent joint plane for a selected normal stress; this observation is significantly different from that observed for the persistent joint plane.