Identification of Microscopic Damage Law of Rocks Through Digital Image Processing of Computed Tomography Images

This paper introduces digital image processing (DIP) to geotechnical field, aiming to disclose the microscopic damage law of rocks under cyclic water invasion. Firstly, the altered granite specimens under cyclic water invasion were subjected to computed tomography (CT) scanning, producing cross-sectional images. These images then underwent noise removal and threshold segmentation. The pores and cores, rock foundation, and high-density nodules were identified accurately in the processed images, reflecting the microstructure of the original rock mass. Based on the processed images, the 3D rock cores were reconstructed, and a 200 x200 x200 representative elementary volume (REV) was extracted from each rock core. The analysis results show that, with the growing number of water invasion cycles, the surface porosity and non-closed surface porosity continued to increase, while the closed surface porosity first increased and then declined. This research lays a theoretical basis for applying the DIP in geotechnical field.