Brittle and Quasi-Brittle Fracture of Geomaterials with Circular Hole in Nonuniform Compression

The author studies the influence exerted by the boundary conditions and diameter of a circular hole on tensile fracture initiation in brittle and quasi-brittle geomaterials subjected to nonuniform compression with regard to the size effect. The calculation of the critical stress uses the modified nonlocal and gradient fracture criteria. The calculation results are compared with the experimental data. The developed criteria allow taking into account the size effect when the size of the stress concentration zone is varied by changing both geometry and boundary conditions of the stress raiser.