Analysis of energy evolution and failure mechanism of cemented tailings backfill with voids

To investigate void effects on cemented tailings backfill (CTB), this study combined uniaxial compression tests with particle flow simulations to analyse mechanical properties, energy evolution, and crack propagation. Specimens included single-void (5, 6, 8 mm) and double-void types with varying arrangement angles (0°, 45°, 90°). Voids significantly weakened the backfill: single-void peak strength decreased linearly by 7.4%–21.6% with increasing diameter, and elastic modulus dropped by 22.4%–55.3%. Among double-void specimens, the 90° vertical alignment exhibited the best performance, with strength 15% higher than the 8 mm single-void sample, indicating that vertical alignment optimises stress superposition and delays crack propagation. Energy analysis revealed altered storage–dissipation patterns: double-void specimens absorbed 11.2% more energy at peak, with post-peak release dominated by dissipated energy. Numerical simulations showed cracks initiating from tensile stress concentrations around voids and propagating obliquely at 45°. Damage evolution followed a Weibull distribution, and the 90° aligned specimen accumulated damage 30% slower. These findings support mine backfill design and defect repair by highlighting the role of void geometry in energy dissipation and stress field optimisation.