Effects of Bedding on The Dynamic Compressive Properties of Low Anisotropy Slate

The dynamic mechanical properties and behavior of transversely isotropic rock are vital in engineering applications. In this study, the dynamic compressive properties of a low anisotropy slate are investigated for five sample groups (θ = 0°, 30°, 45°, 60°, and 90°) using a split Hopkinson pressure bar (SHPB) with three loading levels. A cone-shaped striker is used for achieving a dynamic stress equilibrium. The test results illustrate that the failure patterns of slate at a low loading level can be divided into four major types and that bedding plays an increasingly dominant role in the failure of samples as the dip angle increases. The tensile splitting effect gradually begins to have a prominent influence on the failure patterns as the loading level increases. Moreover, the variations in the failure patterns may lead to a decrease in the strain rate effect when the dip angle increases from θ = 30° to θ = 60°. At θ = 90°, the measured dynamic critical strength is less than the static strength, possibly due to the anisotropic effect of bedding directivity. In addition, the dynamic strength of the slate exhibits a higher anisotropy under dynamic loading, and the strength anisotropy index first decreases and then increases as the loading level increases.