Orientation of meso-components in granite under uniaxial compression using image analysis

The orientation of meso-components in granite was investigated using video images from the laboratory uniaxial compression tests. The video images were converted into static images after the pretreatment of the original ones. The images with the same position and size were clipped and gray-converted in each static image. The distributions of different meso-components at different times were obtained by using different thresholds to recognize each meso-component in granite. The minimum enclosing rectangles were identified by the major and minor axes. The tendencies of each meso-component investigated in the whole region of 0°,360° were obtained according to the positions of the midpoint and the intersections of the major with minor axis. The major axis trend and area and the probabilistic entropy of different meso-components were furthermore computed. The contour maps of the major axis trend and the variation curves of area and probabilistic entropy were thereafter visually drawn out. The whole process of calculation was automatically generated using the programs compiled by the authors. The results show that the orientation of meso-components in granite under the uniaxial compression may be presented using image analysis; the enhancement or decrease intervals of orientation of different meso-components were not overlapped separately; the quartz, feldspar, and biotite were successively loaded during the compressions; the areas of different meso-components during the load process had obvious abnormal changes; the arrangement of biotite has the best order in initial granite; the regions of quartz and feldspar were more ordered than those of biotite in the whole compression process. The findings in the current study may be used as a reference for the investigation of the deformation/failure mechanism of rock materials.