Abstract

In this study, we explore the static and dynamic mechanical responses of layered cemented backfill subjected to blasting loads. Variable-rate uniaxial compression tests and Split Hopkinson Pressure Bar (SHPB) numerical simulations were performed on specimens with three different interlayer cement-to-tailings ratios. All samples were cured for 28 days before testing. The test results reveal that uniaxial compressive strength rises and then falls with increasing loading rates, and mixed tensile-shear failure dominates quasi-static loading conditions. The interlayer cement-to-tailings ratio dominates the bearing capacity of backfill. At the test loading rate of 0.02 mm/s, lowering the interlayer ratio from 1:4 to 1:8 sharply reduces peak strength from 5.595 MPa to 1.285 MPa, with a total drop of 77.0%. SHPB simulation results show obvious strain-rate hardening under dynamic impact. For samples with an interlayer ratio of 1:4, dynamic compressive strength increases from 5.38 MPa to 6.16 MPa as impact velocity rises from 4 m/s to 13 m/s, a 14.5% improvement caused by rapid compaction of internal micropores. Combining damage mechanics and energy conservation principles, we establish a dynamic damage constitutive model that couples inherent layered interfacial damage with blasting-induced dynamic disturbance. Model predictions match experimental measurements well. The peak strength error is only 1.3% at a loading rate of 0.005 mm/s, and peak deviations for all test cases are controlled within 5.0%. This work quantitatively clarifies the static and dynamic mechanical evolution of layered cemented backfill, and provides solid theoretical support for mixture proportion design and blasting stability assessment in high-stage sequential backfilling mining.

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