Abstract
A fracture of brittle solids under compression was discussed. Special attention was paid to the influence of confining stress and the presence of free boundary on a behavior of crack growth. Cracks tend to grow unstably leading a brittle splitting when they are loaded by longitudinal compression together with lateral tension. When the lateral stress is also compression, cracks always grow in a stable fashion. Presence of free boundaries near the crack tend to increase its stress intensity. This increase is mainly caused by the outward bending deformation. A possible mechanism of pseudo ductile deformation (shear rupture) experienced in the compression experiments of rocks was discussed in detail as a result of interference of an echelon of cracks.
