Experimental Study of Reinforced Layered Rocks with a Hard–Weak–Hard Structure under Compression

Abstract

The failure mechanisms of unreinforced and reinforced layered rocks with various layer dip angles were analyzed using acoustic emission (AE) activities, failure modes, and load–displacement responses. The results indicate that the failure mode for both unreinforced and reinforced specimens changes from splitting in the hard layer to shearing in the weak interlayer as the interlayer dip angle increases. The presence of a rock bolt can greatly influence the load–displacement responses and the evolution of AE activities of reinforced layered rocks when the interlayer dip angle ranges from 45° to 60°. Only in this angle range can the rock bolts delay or prevent the formation of splitting cracks. There is a critical interlayer dip angle (60° in this study) at which both strengths for the unreinforced and reinforced specimens can achieve their lowest values. At this critical angle, the most significant reinforcement effect can be obtained. Further analysis indicates that at this critical angle the reinforcement effect decreases as the interlayer thickness and interlayer strength increase.