Study on dynamic fracture behaviour and fracture toughness in rock-mortar interface under impact load

摘要

The stability of grouting reinforced rock structures under impact loading mainly depends on the interface strength between rock and mortar. In this paper, a Bi-material Single Cleavage Triangle (BSCT) specimen was employed in a split Hopkinson pressure bar experiment to investigate the dynamic fracture of the rockmortar interface under impact loading. The interfacial roughness of the specimen was considered in the experiment as well as the loading rates effect. The crack extension velocity in the interface was obtained by the Crack Propagation Gauge (CPG). The stress wave propagation behavior and failure mechanism in the interface were analyzed by the AUTODYN software. Notably, the Complex Stress Intensity Factors (CSIF) were calculated by using the experimental-numerical method. The results show that interfacial roughness and loading rate have a great effect on interfacial fracture behaviour. Compared with the granite-mortar specimen, the stress wave propagation velocity in the sandstone part and mortar part are very close, making it hard to find shear failure in the sandstone-mortar interface. The interfacial crack propagation velocity of the sandstone-mortar specimen may outpace the Rayleigh wave in the intact sandstone. The complicated relationship amongst the loading rates, interfacial roughness, and parameter K1 of the CSIF has been unveiled elaborately in the present paper.