Study on grout cracking and interface debonding of rockbolt grouted system

Tensile tests and numerical analysis of failure models of rockbolt grouted system were conducted in the contribution. The cohesive zone model (CZM) was employed to simulate the interfacial behavior of rockbolt-grout interface and the plastic damage model was adopted for the grout materials. The effects of the interface bond strength and grout compressive strength, etc., on the failure patterns and the load-displacement curves were investigated in detail. Three failure modes of the rockbolt grouted system, namely (1) rockbolt-grout interfacial debonding, (2) complete grout cracking, and (3) a combining pattern of interfacial debonding and grout cracking were identified. The results indicate that there exists a critical bond strength, which controls these failure modes. With the increasing of the bond strength, the failure patterns change from the interfacial debonding to the grout cracking.