Mechanical and Permeability Properties of Cemented Tailings Backfill Under Seepage-Stress Coupling

This study addresses stability degradation of cemented unclassified tailings backfill (CTB) under seepage-stress coupling in deep water-rich metal mines. CTB specimens with diverse mix proportions were prepared to explore their mechanical and permeability responses under varying seepage water pressures, and a response surface regression model was built to quantify multi-factor interactive effects on permeability. Results reveal that increased seepage pressure degrades CTB mechanical performance, while the degradation rate gradually declines. Higher cement-tailings ratios amplify the weakening effect of seepage pressure on elastic modulus. The permeability-strain evolution curve of CTB resembles its σ-ε, and the strain at peak permeability kmax always exceeds peak stress strain. The interaction between cement-tailings ratio and seepage water pressure dominates the variation in kmax and kmin. This work deepens the understanding of CTB seepage-mechanical behaviors and offers experimental references for proportion design and stability assessment of CTB in water-rich underground mines.