Deformation and fracture behavior of granite by the short core in compression method with 3D digital image correlation

Based on three-dimensional digital image correlation (3D-DIC) technique, the deformation behavior, damage and fracture characteristics of the granite specimens have been tested and observed by the short core in compression (SCC) method. The test results show that (1) the damage degree of rock in the region of interest (ROI) increases with axial stress. Before peak stress, damage factor based on apparent principal strain increases slowly, then rises rapidly; (2) relative displacements in both horizontal and vertical directions are observed, indicating that the fracture mode for SCC specimens subjected to uniaxial compression is the tensile-shear mixed mode fracture; (3) new fracture initiates from the middle part of the expected shear fracture band (ESFB) then propagates along the loading direction. A dominant macro-fracture, linking up the tips of two notches, eventually forms. Meanwhile, a calculation method based on the energy conservation law for the fracture energy of SCC specimens is proposed. The fracture energy of granite is estimated as 1760.4 J/m(2).

Automated summary

The deformation behavior, damage and fracture characteristics of granite specimens were tested and observed using 3D-DIC and SCC method. The study found that damage in the region of interest increases with axial stress, relative displacements indicate tensile-shear mixed mode fracture in SCC specimens, and new fracture initiates from the middle part of ESFB. Fracture energy of granite is estimated as 1760.4 J/m² based on energy conservation law.