Abstract: In view of the insufficiency of the present rock damage mechanics models, we propose a statistical constitutive model of rock damage considering the crack closure effect by introducing the statistical damage theory. The model is more consistent with the deformation and failure regularity of rock, and reflects the residual strength and ductility, hence having a wide range of application. The model is proved to be rational and feasible through comparison with the existing research results and measured data. The curves of damage variable under different confining pressures conform with the “S” shape, which can be divided into different phases according to the deformation failure stages. Crack closure coefficient (h) has great influence on the damage energy dissipation rate. With the decrease of h , damage energy dissipation rate increases; when the value of h reaches a certain value, the damage energy dissipation rate rises sharply. Therefore, the deformation failure of rock is not only related with stress state, but also involves the accumulation of damage evolution and crack closure effect.

Key words: rock mechanics, damage, crack closure effect, damage energy dissipation rate, micro element strength