Based on the microstructure-mechanisms of rock materials and a simple mechanical model
a rheology damage constitutive equation is proposed by introducing generalized time defined in the space of irreversible strain and Newtonian time
and an anisotropic damage tensor of rank four. The anisotropic evolution and unilateral effect of damage as well as the effect of hydrostatic pressure can be taken into account in the proposed model. The corresponding numerical analysis is developed; and the creep
inelastic and damage behaviors of claystone are analyzed. It shows that the calculated results agree well with the experimental observation. The influence of stress level on the creep can be well described with the model.