Experimental study on the dynamic behavior of sandstone with coplanar elliptical flaws from macro, meso, and micro viewpoints

Abstract

A series of dynamic tests were performed using a split Hopkinson pressure bar device to investigate the effect of coplanar elliptical flaws with a range of inclination angles on the dynamic behavior of sandstone specimens. The fracturing process was studied from macro, meso, and micro perspectives using a combination of strain gauge (SG), digital image correlation (DIC), and scanning electron microscope (SEM) techniques, respectively. The results show that the dynamic compressive strength and Young’s modulus negatively correlate with the flaw inclination angle. The dominant diagonal shear cracks penetrating the entire specimen ultimately led to slippage along the long axis for small inclination angles (30°, 45°), whereas tensile cracks dominated the macroscopic collapse for specimens with inclination angles larger than 45°. Shear and tensile cracks were effectively identified by DIC and their microscopic surface morphologies by SEM. The strain energy release path was also sensitively related to the flaw inclination angle.