Abstract: The engineering stability of red sandstone is low, and its mechanical properties are greatly affected by the water content and dynamic load disturbance. This study focuses on typical red sandstone in the western Sichuan Plateau region. Using split Hopkinson pressure bar (SHPB) test, different water content and loading strain rate conditions were set to simulate different water contents and dynamic loads disturbance. By employing high-speed camera, digital image correlation (DIC) and other measurement means, the study revealed the influence of deformation and energy consumption characteristics of red sandstone under different water contents and different strain rates. The results show that: (1) The dynamic modulus of elasticity of red sandstone is minimally affected by strain rate but increases with higher water content; the dynamic compressive strength of red sandstone increases with lower water content or higher strain rate. (2) The dynamic Poisson’s ratio of the red sandstone is less affected by water content but increases rapidly with strain rate, ranging from 1.92 (25 s⁻¹ strain rate) to 10.55 (130 s⁻¹ strain rate) when water content is 6%. (3) As water content or strain rate increases, the average fragmentation of red sandstone decreases gradually in a nonlinear manner. An inflection point is observed at 3% moisture content and 60 s⁻¹ strain rate, leading to a significant decrease in the average rate of particle size reduction. (4) At a constant strain rate, the energy dissipation rate and reflectivity of red sandstone specimens exhibit no significant correlation with water content, whereas the energy transmittance decreases progressively with increasing water content. (5) At a fixed water content, the energy transmittance and dissipation rate of red sandstone specimens decrease with rising strain rate, whereas the energy reflectivity increases. The findings of this study offer a theoretical foundation for blasting and excavation operations in water-rich red sandstone strata, as well as for prevention and control of seismic dynamic disasters and other related engineering applications

Key words: red sandstone, water content, strain rate, split Hopkinson pressure bar (SHPB), deformation and strength, digital image correlation (DIC)