Impact dynamic characteristics and constitutive model of granite damaged by cyclic loading

Abstract

To study the influence of damage degree on dynamic characteristics of damaged rock mass, the samples with different damage degrees were obtained by cyclic loading test and then the impact failure test was carried out by a 100-mm diameter split Hopkinson pressure bar (SHPB) device. In addition, the Zhu-Wang-Tang (ZWT) constitutive model was improved to establish the dynamic constitutive model of damaged granite. Results show that when the cyclic upper limit stress (CULS) reached 60% of the compressive strength of rock mass, the Felicity effect was significant and the Kaiser effect basically disappeared. Furthermore, there was obvious compressive strengthening effect of damaged rock mass under impact load, with the increase of the CULS in the early stage, the dynamic compressive strength of granite samples showed an overall decreasing trend. The damage degree had a significant effect on the propagation and energy absorption ability of rock mass, thus affecting its failure characteristics. Eventually, the proposed constitutive model was fitted with the experimental data, which showed that the model could accurately describe the dynamic mechanical properties of damaged granite under impact load.

Keywords

• Rock dynamics
• Damaged granite
• Cyclic loading
• SHPB
• Constitutive model