Research on fractal features of sandstone meso-structure based on digital image processing

In order to study the correlation between the fractal features of sandstone meso-structure and the macro-scopic damage and failure,four typical sandstones selected from E-zhuang Coal Mine of Xinwen coalfield were taken as the research objects. The gray-scale images were obtained by scanning electron microscopy,and the appropriate segmentation method was selected by the experimental goodness method,and the image was processed to obtain the parameter information such as the length,perimeter and area of the sandstone pores and fissures. The fractal dimension of crack in sandstone samples was obtained by slit island method and the damage variables were calculated to study the correlation between the fractal feature, damage variables and strength. The results show that the strength of sandstone is inversely proportional to the fractal dimension of its meso-structure. The higher the complexity of sandstone pore and fracture structure,the larger the fractal dimension and the smaller the uniaxial compressive strength. The fractal features of sandstone meso-structure can provide a basis for the evaluation and influence analysis of its strength characteristics. The damage variable of sandstone has a positive correlation with the fractal dimension,and the damage variable increases nonlinearly with the increase of the fractal dimension. The fractal dimension can better characterize the damage degree and fragmentation degree of sandstone, and also affect the damage characteristics of sandstone.