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| A MICROMECHANICAL CONSTITUTIVE DAMAGE MODEL FOR BEISHAN GRANITE |
| ZHU Qizhi1，2，LIU Haixu1，2，WANG Wei1，2，SHAO Jianfu1，2 |
| (1. Geotechnical Engineering Research Institute，Hohai University，Nanjing，Jiangsu 210098，China；2. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering，Hohai University，Nanjing，Jiangsu 210098，China) |
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Abstract Beishan granite is a typical quasi-brittle rock and its material degradation and structure failure is mainly attributed to the inelastic deformation and the damage development due to microcracks. This paper is devoted to modeling the nonlinear mechanical behaviors of Beishan granite. A damage-friction coupled model was developed based on the method of linear homogenization and the irreversible thermodynamics. The granite was viewed as a heterogeneous material composed of the matrix and a large number of randomly distributed microcracks，and thus our studies started with a representative elementary volume(REV)，i.e. the matrix-cracks system. The free energy of the REV was determined with Mori-Tanaka method and the thermodynamic forces associated with the inelastic strain and the damage variable were derived. The development of the inelastic strain and the damage were determined with the criterion of associated general Coulomb friction and the damage criterion of rate-based strain energy release respectively. An explicit function of the rock strength was derived during the damage-friction coupled analyses. The essential feature of the damage resistance function was described. The proposed multiscale model was finally applied to simulate a series of triaxial compression tests on Beishan granite. The comparison between the numerical predictions and the experimental data validated the model and showed outstanding advantages of the multiscale constitutive formulations over the phenomenological models.
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Received: 10 May 2014
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2015, Vol. 34 
