Transparent characterization and quantitative analysis of broken gangue’s 3D fabric under the bearing compression

Abstract

Broken gangue has been extensively used in rockfill dams, subgrade, embankment, foundation cushion and other engineering construction. The deformation characteristics of broken gangue under the bearing compression play a decisive role in the firmness, stability and safety of these structures (buildings), and the meso-fabric change of broken gangue under the bearing compression significantly affects its macro deformation. In this study, the transparent characterization and quantitative analysis of 3D fabric of broken gangue under the bearing compression were performed through CT scanning test, image processing and 3D reconstruction technology, and the influence mechanism of internal fabric of broken gangue on its macro deformation was revealed. The results show that: In the loading stage of 0–2 MPa, the sharp corners, thin edges on the blocks and the bar-shaped and blade-shaped blocks with poor regularity are broken first under the bearing compression; in the loading stage of 2–8 MPa, a large number of larger particles in the sample are crushed in the mode of fragmentation; in the loading stage of 8–10 MPa, the breakage degree of samples is relieved. The axial displacement of the block inside the sample occurs, as well as the lateral displacement of the block converging to the central axis of the sample. In the rapid deformation stage, the macro deformation of the broken gangue is mainly caused by the rearrangement and adjustment of the block structure and the breakage of the block; in the slow deformation stage, it is mainly caused by the breakage of the block; in the stable deformation stage, it is mainly caused by the optimization and adjustment of the bearing skeleton in the sample.