Study on Dynamic Mechanical Response Characteristics and Constitutive Model of Rocks Under Impact Loading

In this study, impact compression tests were conducted on sandstone, shale, and conglomerate using a split Hopkinson pressure bar (SHPB) apparatus to investigate their mechanical responses and constitutive relationships under dynamic loading. Stress–strain curves at different strain rates were obtained, and the strain-rate enhancement effect, failure mode, and fragmentation fractal characteristics of each rock type were systematically analyzed. Based on continuum damage mechanics and statistical strength theory, a dynamic statistical damage constitutive model for rocks was developed, and the model parameters were identified and validated using experimental data. The results indicate that the proposed model effectively simulates the dynamic mechanical behavior of rocks under impact loading, with theoretical curves showing good agreement with the experimental results. The dynamic compressive strength of rocks exhibits significant strain-rate sensitivity, and the fragment size distribution follows a distinct fractal law. This study provides theoretical support and experimental evidence for dynamic hazard warning and protective design in deep rock mass engineering.