Failure behavior and fracture toughness of Brazilian disc ice specimens with pre-flaws in compression

Understanding the crack propagation mechanism of ice with flaws is of great significance in many ice engineering applications. The failure behavior and fracture toughness of Brazilian disc ice specimens with pre-flaws are experimentally investigated under quasi-static loading. A series of repeated tests are conducted to explore the load-bearing characteristics and damage evolutions of single and double flawed ice specimens with various inclination angles from 0° to 75°. Experimental results indicate that the peak loads of both single and double flawed specimens have a non-monotonic trend, first decreasing and then increasing with increasing inclination angles. The peak loads of double flawed specimens were consistently lower than those of single flawed specimens. Ice samples exhibit significant brittle failure characteristics, with the load–displacement curve rapidly decreasing after the peak load. For the single flawed specimens, those with an inclination angle of ≥ 15°are dominated by wing cracks, while those with an inclination angle of 0° appear the tensile-shear mixed-mode fracturing. The pre-existing flaws in double flawed specimens are prone to coalescence by wing tensile cracks in the bridging zone, and the cracks in the upper region transition from shear to tensile mode. The evolution of deformation field is preliminarily analyzed, and the characteristics of crack initiation are explored based on digital image correlation technology. The generalized maximum tangential stress (GMTS) criterion was employed to conduct the mixed-mode fracture toughness analysis on Brazilian disc ice specimens with single flaw. GMTS criterion provides substantially closer predictions of mixed mode fracture toughness for the experimental results. These results improve the understanding of the crack propagation and failure modes in the ice with initial defects.