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Abstract Microcracks and microvoids are the main microdefects in rock-like materials. When water infiltrates into microcracks，an additional opening stress will be caused on the surface of microcrack. Based on superposition principle，the response characteristics of these rock-like materials which need to consider the water pressure in microcracks under triaxial compression are separated. Considering the deformation，extension and kink of elliptical microcracks in infinite deep buried rock under the condition far field 3D compressive stress，the additional flexibility tensor caused by single closure elliptical microcracks and kink microcracks on any space orientation in a RVE(representative volume element) is obtained. With the assumption that the permeability of the RVE is mainly up to the variation of kink microcrack extension on normal direction under triaxial compression，and making use of the Darcy¢s law and cubic law of laminar flow，the expression of additional permeability tensor of single kink microcrack is derived. Considering the effect of microcrack system on the deformation and permeability of RVE by Taylor¢s scheme，a 3D meso-mechanical coupling constitutive model of damage and permeability in rock-like materials under triaxial compression is obtained by probability density function. The numerical calculation shows that the calculations of this model agrees well with that of test.
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Received: 20 February 2009
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