An energy-based damage model of geomaterials—I. Formulation and numerical results

In this paper\ an anisotropic damage model is established in strain space to describe the behaviour of geomaterials under compression!dominated stress _elds[ The research work focuses on rate!independent and small!deformation behaviour during isothermal processes[ It is emphasized that the damage variables should be de_ned microstructurally rather than phenomenologically for geomaterials\ and a second!order {{fabric tensor|| is chosen as the damage variable[ Starting from it\ a one!parameter damage!dependent elasticity tensor is deduced based on tensorial algebra and thermodynamic requirements ^ a fourth!order damage characteristic tensor\ which determines anisotropic damaging\ is deduced within the framework of Rice|s "0860# {{normality structure|| in Part II of this paper[ An equivalent state is developed to exclude the macroscopic stress:strain explicitly from the relevant constitutive equations[ Finally\ some numerical results are worked out to illustrate the mechanical behaviour of this model[