Numerical simulation study on mesoscopic mechanism of fracture evolution of slag-loess-based cemented backfill material

Backfilling in underground mining is a widely adopted technique, often employing cement-based or geopolymer materials. However, the high cost and logistical challenges associated with these materials in remote mining locations necessitate alternative solutions. Loess materials offer a viable option for reducing production expenses and mitigating environmental impact. Despite this, the mechanical properties of loess-based cemented materials have been insufficiently investigated. This study introduces a novel slag-loess-based cemented backfill material. A three-dimensional model of the backfill material was constructed using Avizo software, and a numerical calculation model, incorporating the actual three-dimensional geometry of aggregate particles, was developed using PFC3D software. The influence of confining pressure σ 3 , curing temperature T C , and age T A on the crack evolution, force chain evolution, and particle failure characteristics during the loading process of the cemented backfill material was systematically examined. Results demonstrate that increasing confining pressure σ 3 accelerates crack initiation and propagation, concurrently increasing the maximum value of the dominant force chain within the specimen at each stage. An increase in age T A has a limited effect on the proportion and quantity of final tensile-shear cracks, though it does intensify the specimen’s ultimate shear failure tendency. At lower curing temperatures (5°C), a significant impact on crack formation is observed, with this effect diminishing as curing temperature T C increases. The macroscopic failure modes of the specimens, across varying temperatures, predominantly exhibit shear failure.