Abstract: In order to explore the instability failure mode and dynamic characteristics of the backfill pillar under the effect of blasting disturbance， taking the tailings cemented backfill as the research object， and three axial pressure levels are selected to carry out SHPB impact test under different strain rate and different transmission paths. The research result shows that: ① under coaxial compression， the dynamic compressive strength of the backfill sample increases with the strain rate. At a similar strain rate， the dynamic compressive strength of the backfill sample shows a trend of increasing first and then decreasing with the increase of the applied axial pressure gradient， the maximum dynamic compressive strength is reached when the axial load is 40% of the static load strength. ②Under dynamic and static combination loading， the backfill sample stress-strain curve is mainly divided into elastic stage，yield stage and failure stage，and the elastic modulus increases first and then decreases with the increase of axial load. ③ The failure mode of backfill under axial compression is shear failure. When the shock wave is transmitted to the backfill by different transfer paths or angles， the failure mode is still shear failure. When there is no axial compression， the failure mode of backfill is split tensile failure. ④Using ANSYS/LS-DYNA to simulate the impact process of the backfill and the coupling body under combined dynamic and static loading， when the shock wave acts on the backfill directly or indirectly through granite， the maximum stress peak appears at the same time，and the stress varies greatly.The attenuation of the stress wave in the backfill is 20%， and the attenuation of the stress wave in the backfill indirectly through the granite is 29%.

Key words: filling mining, impact load, dynamic and static combination, SHPB, failure mode, backfill