RESEARCH ON THE WATER-HOLDING CAPACITY AND MECHANICAL PROPERTIES OF BACKFILL BASED ON A DAMAGE-SOFTENING CONSTITUTIVE MODEL: EFFECTS OF DIFFERENT PERMEABILITY FORCES

This study investigates the application of tailings backfill through a series of centrifugal and pore characteristic tests. To align with the material’s structural properties, a specialized test mold was developed, enabling the preparation of tailings backfill model samples with varying concentrations and proportions. Employing centrifugation and nuclear magnetic resonance (NMR), the study determined the optimal centrifugal force and the T2 critical value for the backfill material. By simulating seepage pressures induced by different centrifugal speeds, uniaxial compression mechanical tests were conducted to analyze the effects of seepage forces on the deformation characteristics and failure modes of the backfill. The results revealed that as seepage force increased, the stress-strain behavior of the samples was altered, with failure modes transitioning from tensile failure to shear failure. This shift was accompanied by an increase in the crack propagation and morphological complexity. Based on these findings, a damage-softening constitutive model incorporating penetration forces was established and validated against experimental data, demonstrating strong agreement. This model provides a robust framework for analyzing uniaxial compression mechanics of backfill materials under varying penetration forces. The outcomes of this research provide valuable insights into high-gravity centrifugal simulations and underground seepage tests, contributing significantly to the design and safety evaluation of tailings backfill systems.