Abstract: To study the dynamic mechanical properties and damage evolution process of the cemented tailings backfill, a separate Hopkinson rod was used to perform impact loading tests on the cemented tailings backfill under different strain rates. The experiment results show that the dynamic compressive strength and the dynamic compressive strength enhancement factor of the backfill increases exponentially with the increase of the strain rate, and the strain rate effect of the backfill with a lower cement content is more significant. The pre-peak energy consumption density, post-peak energy consumption density, strain energy per unit volume, and total energy consumption density of the backfill all show an exponential function increasing law with the average strain rate increase, and the dynamic compressive strength has an obvious positive correlation with the post-peak dissipated energy density. Under the action of impact load, the deformation and failure of the backfill mainly experienced three stages: linear elastic deformation, yield failure and post-peak fracture. The energy is stored in the sample in the form of elastic strain energy in the linear elastic deformation and yield failure stage of the backfill, and the energy is mainly released by dissipated energy in the post-peak fracture stage. Under impact loading, the energy damage evolution process of the backfill is divided into three stages: the damage stable development stage, the damage acceleration stage and the damage destruction stage.

Key words: cemented tailings backfill, impact loading, energy dissipation, mechanical properties, damage evolution