Effect of impact loading and acidic drying-wetting cycles on fragmentation and energy dissipation characteristics of sandstone

Impact loading and exposure acidic mine water considerably influence the safety and stability of rock masses in coal mines during blasting and excavation. To investigate these effects, three different levels of impact tests were carried out on sandstone specimens exposed to five varying acidic drying-wetting cycles, utilizing a split Hopkinson pressure bar (SHPB) device. The pore structure of the sandstone specimens was analyzed by employing Image Pro Plus (IPP) software to segment Scanning Electron Microscope (SEM) images. The findings revealed that, under the same impact air pressure, the energy reflectivity and fractal dimension of the sandstone specimens increased as the frequency of acidic drying-wetting cycles increased. Conversely, the transmissivity, dissipation rate, dissipation energy density, and average fragment size decreased. Furthermore, as the impact air pressure increased, sandstone specimens exposed to identical acidic drying-wetting cycles showed an increased in energy reflectivity, dissipation rate, dissipation energy density, and fractal dimension, while transmissivity and average fragment size decreased. The primary failure modes observed in the sandstone specimens were splitting and crushing. The main pore types identified were micropores and mesopores, whose size and area increased with the frequency of acidic drying-wetting cycles increased.