A Statistical Damage Model Of Rock Failure And Fractured Rock Mass Gradual Damage Numerical Simulation

Traditional rock mechanics based on the phenomenological theory,it is helplessness to explain the mechanism of breaking and the nonlinear mechanical properties of the rock. The finite element method based on traditional theory of rock mechanics cannot simulate the gradual failure process of crack propagation reasonably which related to the generalized time. With geotechnical engineering to a higher, deeper development, some new nonlinear mechanics phenomenon research is inevitable, the development of rock mechanics encount unprecedented challenges. Starting from the rock mesoscopic mechanism, integrate the mesoscopic mechanics, fracture mechanics and damage mechanics and statistical mechanics research achievements, to review the constitutive relation of the rock, appear very necessary.Based on rock microscopic observation, this work regard the generation of micro cracks, extension, cutthrough in rock failure process as the most direct reason and expression form. On the basis of non-equilibrium statistical mechanics theory, the number of micro cracks evolution process, alongwith fracture probability be regarded as the damage variable. A unified rock constitutive equation of rock damage evolution across scales is established by composited mesoscopic damage mechanics and macro process. Studied the size effect law of rock strength and intrinsic scale parameters of the constitutive equation. The influence of initial damage imposed on the stress strain curve, verified the extention model in consistent with the initial damage effects.In order to establish the calculation method of rock gradual damage, the damage evolution equation of embedding smeared crack model to simulate the fracture can satisfy the conservation of unit failure criterion is eslablished,it confirmed that the double scalar damage model and the single scalar damage model are equivalent in the research methods of this article, which verify the synchronicity of the tensile damage and shear damage, An implementation about the method of crack extension theory by using the brittleness model is put forward. An equivalent crack model include rough joints is established to consider the initial fracture mechanics characteristics, and is used to calculate already exist fissures in rock mass, in order to avoid entity modeling difficulty.Finally, on the basis of the above research, a discontinuous joint rock equivalent mechanical parameters determination method is established, by means of discontinuous joint rock loading-unloading numerical experiments, to reserch the failure mode, strength conditions and strength parameters. Results show that the strength parameters obtained by the method of equivalent mechanical parameters is10%-50%higher than the traditional method of engineering rock mass classification.