Influence of block shape on macroscopic deformation response and meso-fabric evolution of crushed gangue under the triaxial compression

Abstract Due to the sharp edges and corners, concave-convex undulations and poor regularity of gangue blocks, the coordination structure of crushed gangue materials is influenced and the occlusive effect, intercalation and stress concentration of gangue blocks are significantly changed during the loading and compression. Based on the CT scanning test and 3D reconstruction technology, the digital 3D model of the real shape of irregular gangue block was obtained in this paper. Based on the two shape indexes of elongation and flakiness, the gangue blocks were divided into four shapes: Knife shape, bar shape, disk shape and cube shape. The numerical model of FLAC/PFC continuous-discrete coupled particle flow for crushed gangues under the triaxial compression was established. Crushed gangue models were made by gangue block containing single shape blocks or mixed-shape blocks. The influence of block shape on the macro deformation response and meso-fabric evolution of crushed gangue under triaxial compression was studied. The main conclusions are as follows: Li et al. (2020a) [1] the more irregular the block shape, the higher the natural accumulation void ratio of the crushed gangue sample. The mixing of irregular blocks in different shapes can increase the natural accumulation void ratio of the sample, and the particle size mixing can significantly reduce the natural accumulation void ratio of the sample; Li et al. (2017) [2] the block shape affects the bearing capacity of the crushed gangue sample, and the worse the shape regularity, the lower the bearing capacity of the crushed gangue sample. The bearing capacity (B) of crushed gangue with different block shapes is ordered as Bcube > Bbar > Bdisk > Bknife; Huang et al. (2017) [3] the worse the shape regularity of the block, the more significant the block movement and fragmentation, and the worse the structural stability of the skeleton force chain. The structural stability of the skeleton force chain (CS) is ordered as CScube > CSbar > CSdisk > CSknife. The research results are of great significance for the further understanding of mechanical properties of crushed gangue materials and the selection and preparation of crushed gangue materials in engineering.