A Micromechanics-Based Elastoplastic Damage Model for Rocks with a Brittle–Ductile Transition in Mechanical Response
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As confining pressure increases, crystalline rocks of moderate porosity usually undergo a transition in failure mode from localized brittle fracture to diffused damage and ductile failure. This transition has been widely reported experimentally for several decades; however, satisfactory modeling is still lacking. The present paper aims at modeling the brittle–ductile transition process of rocks under conventional triaxial compression. Based on quantitative analyses of experimental results, it is found that there is a quite satisfactory linearity between the axial inelastic strain at failure and the confining pressure prescribed. A micromechanics-based frictional damage model is then formulated using an associated plastic flow rule and a strain energy release rate-based damage criterion. The analytical solution to the strong plasticity-damage coupling problem is provided and applied to simulate the nonlinear mechanical behaviors of Tennessee marble, Indiana limestone and Jinping marble, each presenting a brittle–ductile transition in stress–strain curves.
KeywordsBrittle–ductile transition Effect of confining pressure Critical damage Micromechanical model Quasi-brittle rocks
This work has been jointly supported by the National Key Research and Development Program of China (2017YFC1501102), the National Natural Science Foundation of China (51679068) and the 111 Project (B13024).
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