Sustainable Mining and Metallurgy

Bleeding of backfill material has a significant impact on the backfill rate, retaining wall pressure, and mechanical properties of the backfill body, but the current understanding of the bleeding mechanism is unclear. Therefore, the effects of the ash-sand ratio, quality ratio, particle size distribution, and superplasticizer dosage on the bleeding of backfill material were studied, and the evolution of the microstructure during the bleeding process was tested using CT technology. The results show that the bleeding of the backfill material is affected by the particle size distribution, ash-sand ratio, quality ratio, and superplasticizer dosage, and increasing the fine particles, ash-sand ratio, and quality ratio can significantly reduce the amount of bleeding, while adding superplasticizer increases the risk of bleeding. Based on the CT test results and Porous Network Modeling, the bleeding process of backfill material can be divided into five stages: induction period, accelerating period, constant period, consolidation period, and final consolidated period. The formation, development, and closure of the channels occur throughout the entire bleeding cycle. The research results are of great significance for deepening the understanding of the slurry bleeding process and achieving the regulation of slurry bleeding.