Study on the impact damage behavior and infrared radiation evolution characteristics of rock under different drop hammer velocities

Infrared radiation effectively monitors rock deformation and failure, playing a significant role in monitoring dynamic disasters such as rockburst and mine tremors. This study investigates rock fracture modes, mechanical properties, and infrared radiation responses under different impact velocities through drop hammer impact tests. The infrared thermal imaging and infrared radiation anomaly area characteristics during rock impact failure were quantitatively analyzed using infrared radiation frequency distribution. The results show that as impact velocity increases, the maximum impact force initially rises then stabilizes with a slight decrease; the double peak of impact force gradually centers on the first peak; the degree of damage increases before decreasing, with failure cracks gradually aligning with the central axis. The energy conversion rate exhibits a threshold, reaching a maximum of 95.54 % when the initial impact energy reaches 70.68 J. Infrared thermal imaging analysis reveals that the average infrared temperature increment (Delta AIRT) lags behind the maximum infrared temperature increment (Delta MIRT), with Delta MIRT being 43.74 times higher than Delta AIRT at higher impact velocities, and Delta MIRT and Delta AIRT being 3.57 and 6.88 times higher than those at lower impact velocities, respectively. The proportion of infrared radiation anomaly areas increases with impact velocity. At higher impact velocities, the low temperature anomaly area Pl reaches 0.104 %, while the high temperature anomaly area Ph reaches 0.0627 % (Plmax is approximately 3.5 times Phmax). The research findings are significant for assessing rock stability and identifying impact failure.