Experimental Study of Mode I and II Fracture Behavior in Brittle Rock and Concrete Materials Under Biaxial Loading Conditions

The fracture behavior of rock and concrete materials, particularly under combined loading conditions, plays a decisive role in the performance of civil engineering structures. Many concrete and rock structures—such as foundations, underground systems, rockfill dams, and deep subsurface installations—are simultaneously subjected to vertical and lateral loads, which may alter fracture mechanisms and change the overall resistance of the materials. In this study, the fracture behavior of brittle rock and concrete materials under biaxial loading conditions is investigated, and the role of lateral confinement in fracture toughness corresponding to Mode I and Mode II is evaluated. To examine the effect of confinement, cracked Brazilian disk specimens were used and variations in fracture toughness were analyzed under different confinement ratios. The results indicate that the presence of lateral stress can alter crack propagation paths and stress intensity factors, leading to mixed-mode fracture. This research can serve as a basis for a more accurate understanding of brittle material behavior in structures subjected to multiaxial loading conditions.

کلیدواژه ها:

Fracture Mechanics ، Mode I and Mode II Fracture ، Biaxial Loading ، Confinement Effect ، Rock and Concrete Materials