Strain-induced damage of rocks
This paper deals with a constitutive equation, which can represent damage induced in rocks by maximum shear strain. In the constitutive equation, the anisotropic damage parameter and dilatancy coefficient are introduced so that the normality rule commonly used in elasto-plastic constitutive equation is not needed. The validity of the proposed constitutive equation is proved by using sands tested in laboratory. The anisotropic damage parameter and the dilatancy coefficient are determined for different type of rocks to discuss the damage process of rocks during the increase of maximum shear strain.