Study on microcrack propagation and evolution of fractured coal-rock based on mineral particle model

Abstract

In order to explore the influence of heterogeneity on the deformation localization and the failure mechanism of fractured coal-rock, the characteristics of stress and displacement vector fields of fractured coal-rock during the deformation and fracturing process were investigated based on the constructed discrete element numerical model considering mineral components, and the evolution of micro-tensile cracks, tensile-shear mixed cracks and compressive shear cracks were quantitatively obtained. The results show that the initiation and expansion of tensile cracks and tensile-shear mixed cracks are almost simultaneous, and the tensile cracks initiate earlier than those of compressive-shear cracks. The accumulation area of compressive stress is mainly distributed around the fracture tip and rock bridge area, whereas the accumulation zones of tensile action are mainly distributed in the area far away from the pre-existing fracture. With the increase of the rock bridge angle, the crack leading the rock bridge through failure changes from the indirect through failure mode, which is approximately parallel to the axial tension mixed failure, to the direct through failure mode of shear and extrusion failure. In addition, the initiation stress levels of the micro tensile crack and shear crack show a gradual increase trend.

Keywords

• heterogeneity
• mineral particle model
• fractured coal-rock
• crack propagation
• vector filed