For the Three Gorges granite

a finite difference software package FLAC is used to study failure process of heterogeneous rock material. Firstly

proper scale of finite difference grids is under consideration with scanning electron microscopy photo of the granite. Based on mineral components identification results of the granite and fuzzy clustering method

the actual image data are transformed into the finite difference grid by applying image processing techniques. A convenient and efficient two-dimensional numerical modeling method for heterogeneous geomaterials is presented. Furthermore

shear bond propagation and failure process of the granite are simulated in uniaxial compression test based on experimental strain soft model; and stress concentration phenomena are analyzed. Finally

numerical simulation of granite samples under different triaxial compression tests is studied. The results show that the numerical modeling method based on digital image processing can be used to calculate the mechanical responses of geomaterials by taking their heterogeneities into considerations.