Dynamic fracture analysis of sandstone specimens containing different inclusions

Infilling materials are commonly distributed in natural rocks, which play a key role in the stability of rock en-gineering. To reveal the enhancing mechanism of inclusions, dynamic uniaxial compressive tests were carried out on sandstone specimens containing double elliptical flaws using a split Hopkinson pressure bar (SHPB) system and the digital image correlation (DIC) technique, and three inclusion conditions (R1, R2 and R3) and three flaw inclination angles (0 degrees, 45 degrees and 90 degrees) were taken into consideration. The results indicate that the inclusions (R2 and R3) with a similar wave impedance to sandstone matrix can maximally enhance the dynamic strength of flawed specimens by 46.82% and 42.83%, respectively. The crack initiation and propagation behavior were significantly changed after the flaws were filled with different types of inclusions. The dominant crack in the bridge area can be identified by strain histories and stress intensity factors (SIFs) at the inner inclusion tips. The findings are projected to deepen the understanding of interaction mechanism of rock matrix and inclusions.