Experimental study of the dynamic tensile properties of water-saturated sandstone with different length-to-diameter ratios

In mining engineering, underground structures such as roadways are often situated in groundwater environments, and it is common for tensile failure to occur under dynamic loading; however, studies on the size effect of dynamic tensile strength in saturated rocks remain relatively rare. In the present study, an improved Split Hopkinson Pressure Bar (SHPB) was used to conduct dynamic Brazilian disc tests on four groups of watersaturated sandstone specimens with a diameter of 50 mm and lengths of 25, 30, 40, and 50 mm. The experimental results indicate that the dynamic tensile strength of saturated sandstone exhibits significant loading rate and size effects. Specifically, when the loading rates are 200 GPa/s and 250 GPa/s, the dynamic tensile strength increases with the length-to-diameter ratio of the specimens. Additionally, the energy absorption density of saturated sandstone also shows a size effect, which decreases with the increase in the length-to-diameter ratio under the same incident energy. The reasons for the size effect on the dynamic tensile strength of saturated sandstone are discussed from the perspectives of energy absorption and utilization, combined with the scanning electron microscope (SEM) images of the fractured specimens.