Behavior of Jointed Rock Specimens Reinforced with Bolts under Uniaxial Compression

Discontinuously jointed rock mass is very common in rock engineering, and it has the characteristics of discontinuity, inhomogeneity, and anisotropy. Bolt has been an economic and effective technique to support underground rock mass, but the understanding of the bolt reinforcement mechanism to jointed rock mass remains limited. Uniaxial compression test of multi-joint reinforced rock specimen was carried out with a fully grouting bolt. The mechanical properties and failure modes of these specimens are investigated. The experimental results show that the rock bolts can significantly improve the strength of jointed rock-like specimens. When the joint angle is 30 degrees and the anchorage angle is 0 degrees, the peak strength of the specimen increased by 80.76 %, and Young's modulus increased by 117.83 %. The peak strength of the bolted rock-like specimen decreases with the increase of anchorage angle and increases with the increase of joint angle. The stress at the onset of dilatancy of the rock specimens clearly increases after the rock bolt is applied, and it decreases as the anchorage angle increases. The rock-like specimens after bolting show better ductility and integrity, and the specimens show apparent volumetric dilatation during failure. A strain-softening model of rock and the pile element in FLAC3D are used to carry out numerical simulations (Itasca Consulting Group, Inc. 2012). The mechanical characteristics obtained by the simulation are consistent with the laboratory results.

Automated summary

Bolt reinforcement can significantly improve the strength and modulus of jointed rock mass. The strength of the bolted rock-like specimen increases with the joint angle and decreases with the anchorage angle. The bolted specimens exhibit better ductility and integrity.