A three-dimensional statistical damage constitutive model for geomaterials

We present a constitutive model for geomaterials. The unified strength theory, which is modified to be more suitable for the geotechnical engineering, is introduced to reflect the effect of the intermediate principal stress. The polyaxial test data of several rock types verifies that the unified strength theory is versatile. The failure of the micro-elements of material is supposed to be distributed randomly and follows Weibull distribution, and the strengths of elements obey the unified strength theory. A statistical damage variable is proposed. Based on the continuum damage mechanics, a statistical damage constitutive model under the complex stress state is proposed. The proposed model is verified by the tests of soft rock. The result shows that the model can well predict the stress-strain relationship of soft rock, especially the strain softening behavior. The influences of the parameters of the model are investigated.