Application of the Finite Fracture Mechanics Approach to Assess the Failure of a Quasi-Brittle Material With a Circular Hole

— The size effect of the strength of structurally inhomogeneous materials is manifested, in particular, in the dependence of the failure load on the size of the stress concentration zone that occurs near material or geometric inhomogeneities (inclusions, pores, cutouts, fillets). Although the size of the stress concentration zone is determined primarily by the size and shape of the inhomogeneity, the loading conditions also have a certain effect. In addition, the predictive value of the fracture theory is determined not only by the ability to take into account the size effect, but also by the possibility of extending the theory to the widest possible range of boundary conditions. The influence of boundary conditions and hole diameter on the initiation of tensile cracks at a circular hole in a quasi-brittle geomaterial under non-uniformly distributed compression was studied theoretically and experimentally, taking into account the scale factor. On the basis of the approach of the finite fracture mechanics, a criterion of quasi-brittle fracture is proposed. The results of calculating the critical stress are compared with the obtained experimental data.