Abstract：The constitutive model is formulated within the irreversible thermodynamics framework，appling the basic principle of energy dissipation；the effective strain of the elastic-damage，the evolution equations of the damage and the yielding criterion of the damage are derived. The constitutive equations for the damaged rock mass are written according to the principle of strain energy equivalence between the raw rock mass and damaged rock. The damaged rock mass is modeled by using the constitutive laws of the effective undamaged rock mass in which the nominal stresses are replaced by the effective stresses. An additive decomposition of the total strain into elastic and inelastic parts is adopted. The elastic part is further decomposed into two portions，one is recoverable elastic distortion and the other is unrecoverable elastic distortion，namely elastic damaged distortion. The inelastic part is also decomposed into two portions，one is plastic distortion and the other is crack closure distortion. The proposed models are applied to analyze the stability of caverns of which the result gives the damage values and zones of the surrounding rock mass of caverns. These values and zones show where damage and fracture occur. The paper supposes that when the damage value is equal to 1.0，the rock mass is defined as fully fractured. And then the method changes to macro-fracture mechanics. So the method provides some theoretical foundations for the micro-mechanics and some ways of the macro analysis in the fields of rock mass engineerings.
