Abstract: Triaxial compression tests were conducted on marble specimens to obtain a single fully-penetrated cracked surface under different confining pressures, and fractured specimens were reinforced by "cement grouting" and "bolting-grouting" with a self-made fixture. Triaxial compression tests were carried out again on the reinforced specimens under the original loading failure confining pressure. By combining with the laser scanning technique and scanning electron microscopy, we analysed the reinforcement effect and mechanism of grouting and anchoring. Experimental results show that the bonding effect of grouting reinforcement causes the cohesion of the fracture surface of the fractured marble, and the shear and tensile effect of the anchor can further improve the strength of the fractured surface. The shear displacement corresponding to the peak shear stress of marble cracked surface strengthened by grouting is almost equal to that of marble strengthened by bolting-grouting, which indicates that the shear and normal loading effects of anchors can be effective when there is a certain shear deformation. Finally, based on the Mohr-Coulomb strength criterion, a shear strength formula of cracked marble bolting-grouting surface with low surface roughness and filling degree greater than 1 is proposed, which is proved to be reliable. To some extent, the experimental results could provide reference for support optimisation of deep hard rock engineering.

Key words: cracked marble, grouting reinforcement, bolt reinforcement, strengthening mechanism, shear strength