Image-based numerical study of three-dimensional meso-structure effects on damage and failure of heterogeneous coal-rock under dynamic impact loads
This paper proposes a numerical three-dimensional (3D) mesoscopic approach based on the discrete element method combined with X-ray computed tomography (XCT) images to characterize the dynamic impact behavior of heterogeneous coal-rock (HCR). The dynamic impact loading in three directions was modelled to investigate the effects of the 3D meso-structure on the failure patterns and fracture mechanism, with different impact velocities. The XCT image-based discrete element model of HCR was calibrated through appropriate standard uniaxial compression tests. Numerical simulations were carried out to investigate how the breakage behaviors are affected by different loading directions with different impact velocities. The loading direction, input energy, and spatial distribution of the mineral phase had a remarkable influence on the failure patterns and load-carrying capacities. The shape of the gangue phase and the approximate location of the gangue interfaces are key parameters to consider when investigating the failure patterns and fracture mechanism of heterogeneous rock materials. The damage and fracture tended to propagate from the surfaces to the HCR interior. The gangue phase area contacting the loading wall, growth direction of the strong gangue interfaces, and loading directions greatly influenced the failure patterns of the heterogeneous rock materials.
Keywords: Heterogeneous coal-rock, Impact loads, X-ray computed tomography (XCT), 3D image-based discrete element modelling, Failure pattern