3D image visualization of meso-structural changes in a bimsoil under uniaxial compression using X-ray computed tomography (CT)

In situ quantification of the meso-structural changes in block-in-matrix-soils (bimsoil) is crucial for stability predictions. While the macroscopic failure of bimsoil has been widely studied, the physical meso-scale mechanisms governing bimsoil deformation have not been well understood. Here, high energy X-ray computed tomography (CT) measurements were performed on a bimsoil sample with a rock block percentage (RBP) of 40% under uniaxial compression to collect three-dimensional data for the sample's meso-damage evolution. The 3D pattern of the sample deformation was imaged in real-time, and meso-structural changes are visualized by the rendered CT images. The data showed that cracks propagated by passing rock blocks, leading to a macroscopic fracture with a well-developed twisting characteristic. The crack rose diagram reveals the propagation path of the cracks, which are mostly parallel to the loading direction. In addition, interlocking occurs during the propagation of cracks, which determined the curved morphology of the fracture plane. Moreover, the fractal 3D digital image analysis quantifies the complexity of the crack distribution with increasing sample deformation. This work demonstrates the strong influence of local mechanical variations due to existing rock blocks on the crack propagation in bimsoil.