Study On Dynamic Characteristics Of Cemented Backfilling Under Impact Loading

The cemented backfill is core of controlling the ground pressure,and it is important to the Mining.The backfill not only subjected to static load,but affected by dynamic loads,which seriously threatens the stability of the cemented backfill.In order to study the dynamic characteristics of cemented backfill,the SHPB device was used to carry out the dynamic test of the backfill under impact loading.Research indicates:1)The deformation characteristics of the backfill are significantly different with the change of the average strain rate.With the increase of the average strain rate,the trend of the post-peak phase of the stress-strain curve under uniaxial impact is“strain rebound”-“stress drop”-“post-peak plasticity”;after applying axial pressure,the trend is"Strain rebound"-"post-peak plasticity"-"stress drop".2)The dynamic compressive strength increases obviously.Under uniaxial impact,with the increase of the average strain rate,the dynamic compressive strength increases first and then stabilizes.The maximum value is 10.12MPa.After the axial pressure is applied,the dynamic compressive strength increases first and then decreases,the maximum value is 10.12MPa.The critical strain rate is about 80s^-1.3)Under uniaxial impact load,with the increase of incident energy,the absorption energy per unit volume of the sample gradually increases and then stabilizes.and the critical incident energy is 40J.Under coupled dynamic and static loading,the absorption energy per unit volume increases first and then decreases with the increase of strain rate.The absorption energy per unit volume decreases with the increase of axial pressure when the strain rate is approximately equal.4)When the impact load is small,the skeleton structure of the sample will not be destroyed,but many cracks are generated inside.As the average strain rate increases,the specimen undergoes splitting and tensile failure,when strain rate exceeds 100s^-1,the sample will be pulverized.After the application of axial pressure,the outer layer peeling phenomenon is obvious,that is the same as failure in the actual production of the mine.Figure50;Table5;Reference 108.