ABSTRACT
ABSTRACT: The “weakness plane model” was developed to simulate the effects of various stress states on the strength of rocks. The model assumes numerous planes of weakness whose directions are uniformly distributed in a rock; each plane slips or opens based on the Coulomb criterion with a tension cut-off; and the rock is regarded as failed when the ratio of the failed plane number to that of all planes reaches a certain value. The same size and strength parameters were assigned to all planes and no complicated statistical functions are used. The model has been applied to true triaxial compression, uniaxial tension, Brazilian and extension tests. The model is very simple but the effects of a stress state are simulated very well. Stress and plane failure distributions on the Schmidt net has increased the understanding of the mechanism of stress state effects on rock strength.
