The strain softening model of rock damage under compression and tension

Sa？etak Deformation and failure of brittle material under compression are different from those under tension. The differences are characteristic for the brittle material such as rock, concrete and others. At present, few constitutive models for rock can reflect the differences. A damage-induced softening model for rock constitutive relations is presented based on statistical strength theory, continuum damage mechanics and elastic mechanics. The model can consider properties of rock mechanics such as strain softening, difference in strength between compression and tension, non-liner stress-strain relation, compressive hardening, brittleness and so on. The model is well-adapted, simple and practical as it is flexible and has only 7 parameters which can be easily obtained from uniaxial test under compression and tension. Under triaxial compression, uniaxial compression and uniaxial tension, the stress-strain relations obtained from the presented model are compared with those obtained from laboratory tests. The comparisons show that the differences between results obtained respectively from the presented model and laboratory tests are small. The presented model is rational