Phase Field Characterization of Rock Fractures in Brazilian Splitting Test Specimens Containing Voids and Inclusions

Abstract

The Brazilian splitting test is a broadly adopted testing procedure for characterizing the tensile strength of natural rock or rock-like material. However, the results of the Brazilian test on specimens with naturally existing voids and inclusions are strongly influenced by size effects and boundary conditions, and numerical modeling can assist in explaining and understanding the mechanisms. On the other hand, the potential of utilizing the Brazilian test to characterize inhomogeneous deformation of rock samples with voids and inclusions of dissimilar materials still awaits exploration. In the present study, fracture mechanisms in Brazilian disks with circular voids and filled inclusions are studied by using the phase field model (PFM). The finite element method is adopted to implement the PFM to study the influence of diameter, eccentricity, and quantity of the voids and inclusions on the fracture patterns and stress-strain curves. The phase field simulations can reproduce previous experimental phenomena and furthermore it deepens the understanding of the influence of inclusions and voids on the fracture pattern, overall strength, and deformation behavior of inhomogeneous rock. The findings in the study highlight the potential of characterizing inhomogeneous rock through combining Brazilian tests and numerical modeling.