Effect of interface roughness on fracture energy and fracture process zone of rock-concrete specimens

To investigate the effect of interface roughness on the fracture behaviors of rock-concrete specimens, the acoustic emission (AE) and digital image correlation (DIC) techniques are used to monitor the fracture process of the granite-concrete specimens with different interfacial roughnesses under three-point bending (TPB) load. The initial fracture toughness of rock-concrete specimens with different interfacial roughnesses is calculated. The characteristic parameters of the AE are also discussed. Based on the fracture mechanics theory, the transient critical response equation and the stress-crack opening displacement model for the rock-concrete interface crack opening displacement (COD) based on micro-macro crack interactions are established. The determination of the model parameters is achieved by the DIC technique, and the fracture energies of interfaces with different roughnesses are calculated based on the model with the determined parameters. The validity of the model is verified by comparing the calculation results with those from the existing fracture energy calculation methods.