Study on fracture shape distribution characteristics and micromechanical properties of middling coal

Abstract

In order to study the fracture shape distribution and micromechanical properties of middling coal containing fracture fillings, the fracture information of coal samples was obtained using the morphological edge detection method. The results showed that the number of Y-shaped fractures was much greater than that of the X-shaped fractures, and the number of single fractures accounted for a larger proportion of the surface fractures. The micromechanical characteristics of the middling coals were analyzed qualitatively based on the nanoindentation load-displacement curve by the surface of middling coal containing fracture fillings. The mechanical properties of the fracture filling zone were nonuniform owing to the presence of multiple minerals, and the crack breaks along the interface or the side of the matrix having poor mechanical properties under an applied force. The difference in mechanical properties at the mineral-mineral interfaces was determined through the nanoindentation test to judge the fracture mode.