Experiments in biaxial compression on brittle materials are presented in this paper. Two of these were on resin samples each containing a single embedded disc-like crack. The results showed that unlike the experimental observations in uniaxial compression (Dyskin et al., (5)) where the crack growth was limited and did not cause failure, in these experiments the crack grew extensively parallel to the load directions and caused splitting. Thus, the presence of the intermediate principal compressive stress changes the mechanism of crack growth. A model is proposed based on representing the growing crack as a disk-like crack oriented parallel to the loading direction and opened by a pair of concentrated forces at its centre. It is shown that the crack growth is stable until it reaches a size comparable to its distance from a free surface.
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