Assessing the degree of coal tectonic disturbance by multifractal analysis of scanning electron microscopy images of coal specimen surfaces

The application of a multifractal approach to assessing the degree of coal disturbance is shown using a series of 2D model configurations of coals and scanning electron microscopy (SEM) images of coal specimen surfaces. For this, multifractal spectra, also called multifractal signatures, are used, which are suitable for a comprehensive description of the structural organization of the surface of coals with different degrees of disturbance. It is shown that maximum values of the multifractal signatures can be used to assess the degree of coal disturbance, and higher values of the parameters are obtained for coal specimens taken from more disturbed coal seams. As a result of the study, six coal disturbance classes have been identified, corresponding to the disturbance classes for model coal configurations generated for the following disturbance threshold values: 3/9, 4/9, 5/9, 6/9, 7/9 и 8/9.