Static mechanical characteristics and meso-damage evolution characteristics of layered backfill under the condition of inclined interface.

• Compressive strength is more sensitive to solid mass fraction. • The number of fractures decreases with increasing dip angle. • Higher particle forces at the delamination interface. • The change of angle has a great influence on the bond strain energy. The volume of the goaf in the hard rock mine vacancy method is much larger than the filling capacity. The existence of layered interface and stacking angle during the filling in large-size goaf complicates the stress of layered structure surface, and the influence mechanism of filling physical properties is unknown. Therefore, the mechanical properties of backfill samples with slurry concentrations of 68%, 70%, 72%, and 74% and stratification angles of 2°, 4°, 6°, and 8° were tested using solid waste of metal ore. The reduction law of compressive strength of backfill under the influence of interlayer inclination was analyzed. The development law of micro-cracks was further studied with particle flow code. The study shows that the uniaxial compressive strength decreases with the polynomial function, and the uniaxial compressive strength rises with the solid mass fraction. The internal crack of the layered cemented tailing backfill begins to sprout when the stress reaches 60% of the peak strength. The crack evolution curve reaches the inflection point when the stress reaches the peak strength. The distribution of fine packing cracks becomes more concentrated and decreases with the increase in the interlayer inclination. The influence of the energy evolution is mainly reflected in the decrease in the bonding energy conversion ratio and the increase in the dissipation energy conversion ratio. [ABSTRACT FROM AUTHOR]