In situ stress concentrations and dynamic disturbances are two important factors causing disasters in deep cavities. In this study, to provide further insights for revealing the dynamic catastrophes of the deep surrounding rock, the deep cavity was first simplified as a rock specimen with a circular hole, and the dynamic mechanical properties and failure characteristics of the holed rock specimen under static coupled dynamic loads were then tested by using an improved split Hopkinson pressure bar (SHPB) and Digital Image Correlation (DIC) technique. The results indicate that small static loads can enhance the dynamic strength of the holed rock specimen, while large static loads cause damage to the specimen and decrease the overall strength. The static loads induce the strain energy accumulation of the holed rock specimen, especially in the vicinity of the hole and when the specimen is in the elastic deformation stage. The accumulated energy can also provide energy for rock damage and failure once it is released rapidly, even inducing significant rockbursts inside the hole. The primary failure of the holed rock specimen under static coupled dynamic load always appears near the hole, and the final failure mode is determined by both static and dynamic loads. Analysis of static and dynamic stress concentration revealed that the failure of the surrounding rock changes from compression to compression-shear or shear as the distance to the cavity increases, which agrees with the experimental results.
Zhao et al. (Tue,) studied this question.