A novel SEM-based heterogeneous coal micro-structure reconstruction and its application on modeling of deformation and failure behaviors

ABSTRACT：Scanning electron microscope (SEM) has been widely used to characterize coal micro-structure. However, SEM images often provide qualitative descriptions which cannot be directly applied to modeling of coal deformation and failure behaviors. In this paper, a PFC^2D approach for modeling heterogeneous coal micro-structure is proposed. First, coal samples were scanned by SEM to study micro-structural characteristics and obtain the digital images. Second, Matlab was used to binarize images and filter small zones and scattered spots in images for obtaining gray images that reflect internal micro-structure of coal samples. Finally, gray images processed by Matlab were imported to particle discrete element software PFC^2D, to further construct a numerical model. With the proposed PFC^2D numerical model, biaxial compressive test was performed on heterogeneous coal samples for the purpose of studying stress-strain curves of coal samples under different confining pressures, and their failure forms. Also, test results between heterogeneous and homogeneous coal samples were compared. The test results indicate that confining pressure can increase coal samples' strength to some extent. The stress-strain curves derived from simulations were consistent with previous research results, thereby proving that the proposed PFC^2D modeling method using SEM images into coal deformation and failure behaviors is reasonable.