Investigating dynamic fracture in marble-mortar interface under impact loading

Abstract

• Compared with the M-S-750 series specimens, the transgranular phenomenon is more common in the M-R-750 series specimens. • The crack propagation velocity in the BSCT specimen is lower than the speed of Rayleigh wave in the M40 mortar. • With the increase of loading rate, the crack propagation speed between CPG adjacent wires does not necessarily increase. • The discrepancy of wave impedance between marble and mortar results in the existence of shear stress in the interface zone of the BSCT specimen. • Compared with the BSCT specimens with smooth interfaces, the fracture properties ( K 1 and G ) of the BSCT specimens with rough interfaces are improved significantly. The mechanical property of the mortar-rock interface is a key factor in dominating the effectiveness of many reinforcement measures in rock mass engineering. Investigating the mortar-rock interface is of important practical consequences. In this paper, a bi-material single cleavage triangle (BSCT) configuration, composed of marble and mortar, was employed in a split Hopkinson pressure bar (SHPB) experiment with interface roughness and loading rates considered. The experimental–numerical method was used to obtain the crack initiation energy release rate G and the complex stress intensity factor ( K = K 1 + i K 2 ) of the onset interface crack. Besides, AUTODYN software was applied for analyzing the propagation law of stress waves in the BSCT specimen, and the failure mechanism of the mortar-rock interface was revealed. The results show that the interface crack growth rate in the BSCT specimen is lower than the P-wave, S-wave, and Rayleigh wave in the M40 mortar. The discrepancy of wave impedance between marble and mortar results in the existence of shear stress in the interface zone of the BSCT specimen. As the loading rate increases to 920 GPa/s, the fracture properties ( K 1 and G ) of all BSCT specimens are significantly improved. The improvements in the fracture properties are more significant for the BSCT specimens with rough interfaces compared to the BSCT specimens with smooth interfaces.