Experimental and Numerical Investigation on the Dynamic Failure Envelope and Cracking Mechanism of Precompressed Rock under Compression-Shear Loads

The complex response of underground geomaterials subjected to dynamic disturbance arises from the microstructure redistribution under high in- situ stress and resulting fracture behaviors at multiaxial states. Inclined specimens were employed in an axially constrained split Hopkinson pressure bar (SHPB) system achieve a combination compression-shear states static-dynamic loads. loading rate investigation ranged 500 4,000 GPa/s, along with axial prestress 7, 21, 35, 49, 63 MPa on inclination 0°, 3°, 5°, 7°. modified SHPB experimentation discrete-element method modeling implemented unravel combined effects rate, preload, path failure mechanism sandstone involving strength envelope, fracturing pattern, fragmentation, microcracking process. positive dependence Drucker–Prager envelope was observed. preload showed double strength, indicated by upper bound as it expanded increasing preload. microdamage accumulated during preloading global field collectively influenced pattern inclined specimen, altering shear mode or high-preload splitting near specimen surface low-preload loading.