PARTICLE FLOW SIMULATION OF DEFORMATION AND FAILURE MECHANISM OF GRANITE BASED ON ACTUAL DISTRIBUTIONS OF MESO-COMPOSITIONS

The granite is a heterogeneous rock with the deformation and failure mechanism depending on the distributions and interactions of the meso compositions, including feldspar, quartz and biotite. The heterogeneity and macro-meso relation could be considered using the particle flow model in the current study. The test video images of the granite from Beishan were photographed during the uniaxial test. The conventional mineral recognition method and the grayscale threshold segmentation were then used together to get the actual distribution of each compositions in a frame extracted from the video images. The initial distributions were generated using the package FishTank of particle flow code in two-dimensions(PFC2D).The distribution of each composition was used to determine the types of particles in the initial locations. The interaction between compositions was characterized by the normal contact strengths between particles. The meso mechanical properties were determined by the macro mechanical properties. The particle flow model of granite based on the actual distributions was thereafter established. And the evolution of fissuring and force chain during the process of deformation and failure was discussed. It shows that the sum of squares of relative error between the simulated results and the actual ones is meet reliability requirements; the major fissuring generated in process of deformation and failure of granite was parallel to the direction of compressive stress; most of the fissuring was distributed in feldspar and was tensile fissuring; the evolvement of force chain network is in accordance with the process of deformation and failure of granite. The studied objects in the current study are the actual heterogeneous locations of the compositions in granite, it is reflect the substantive characteristics of petrographic composition and the presented results may be of great significance in investigating the macro-meso relations and forecast the process of deformation and failure for heterogeneous rock materials.