Dynamic energy evolution and fragmentation characteristics of damaged rock under impact compression loading

In sharp contrast to prefabricated cracks, the damage to rock masses resulting from external disturbances such as excavation disturbances and tectonic movement varies substantially as to the incidence, density, and magnitude of defects. The growth ratio of the energy dissipation density proportion D(R_ω (α)) of the damaged rock under impact loading is closely related to the static damage factor D(α) and is theoretically explored based on the Weibull distribution in this paper. Sandstones with varied damage levels after distinct static precompression, as described by CT imaging, are used to evaluate the impact load of different driving pressures. In addition, a high-speed camera and geometric fractal are used to exhibit the ejection and fragmentation characteristics of the pulverized sandstones after impact loading. The experimental outcomes confirm the theoretical study where the function of D(R_ω (α)) involving D(α) obeys the Weibull distribution, and the D(R_ω (α)) slowly rises with the expansion of the damage factor. With the increase of either the damage level or driving pressure of the sandstone, the number of pulverized rocks, the fragmentation degree, and the D(R_ω (α)) all increase. These results further advance rock dynamic theory and corroborate the energy evolution, ejection, and fragmentation characteristics of damaged sandstone under impact loading. These results can also serve as references for rock dynamic risk mitigation under dynamic catastrophes..