In Situ X-Ray CT Investigations of Meso-Damage Evolution of Cemented Waste Rock-Tailings Backfill (CWRTB) during Triaxial Deformation

This work presents an experimental study that focused on the meso-damage evolution of cemented waste rock-tailing backfill (CWRTB) under triaxial compression using the in situ X-ray computed tomography (CT) technique. Although numerous investigations have studied the magnitude of the strength of CWRTB material, the mesoscopic damage evolution mechanisms under triaxial deformation are still poorly understood. Artificial CWRTB samples with a waste rock proportion of 30% were prepared by mixing tailings, waste rock, cement, and water. A specific self-developed loading device was used to match the CT machine to real-time CT scanning for the CWRTB sample. A series of 2D CT images were obtained by performing CT imaging at five key points throughout the test and from three positions in the sample. The CT values, for the purpose of meso-damage evolution in CWRTB, were identified. The results showed that the axial stress–strain curve presented strain hardening characteristics. The CT data revealed the inhomogeneous damage field inside the CWRTB sample and the most severely damaged regions that were usually located at the waste block-tailings paste interfaces. The changes in CT values for the different regions of interest (ROI) revealed the complicated interactions between the waste blocks and the tailings paste matrix. The meso-structural changes, formation of the localized bands, and the associated stress dilatancy phenomenon were strongly influenced by the interactions between the waste blocks and tailing paste. View Full-Tex