Dynamic behavior of a running crack crossing mortar-granite interface with different interface inclinations

Abstract

High-strength mortar is widely applied in fractured rock reinforcement due to its strong bonding strength, where crack propagation crossing the interface is commonly seen. To investigate the dynamic crack propagation behavior across the interface, A side material cleavage triangle (SMCT) sample was adopted in this study with different interface inclinations and mortar strength considered. Impact testing of a split Hopkinson pressure bar (SHPB) system was conducted and cohesive models were established to explore the penetration process of the extending crack. With the numerical result and the measurement of the crack propagation gauges (CPGs), the dynamic stress intensity factor (DSIF) was determined using an experiment-based numerical method. The investigation results show that the excited crack always propagates across the mortar-granite interface regardless of the stiffness difference, and this phenomenon remains unchanged with increasing interface inclination. For SMCT specimens, as the strength grade of mortar increases, the time taken for cracks to propagate through the interface increases. As the interfacial inclination increases, the time taken during crack penetration through the interface is longer. Using Python coding, cohesive elements can be embedded in batches in the numerical model to simulate crack propagation behavior at the interface. As the interface inclination increases, the DSIF in both the mortar and granite regions exhibits an upward trend.