Experimental On The Static And Dynamic Mechanical Properties Of The Early Strength Agent Doped Full Tailings Cemented Backfill

It is of momentous significance to improve safety and short mining and filling period in the mines of used stratified backfill mining technology.The early strength of backfill can be improved by doped early strength agent.But the backfill endured static load from deadweight,confining pressure,top pressure etc beyond dynamic load from blasting vibration,impact etc alone.In this paper,the laboratory experimental were conducted aiming at static and dynamic mechanical properties of the early strength agent doped full tailings cemented backfill.Specific contents are as follows:?1?The static and dynamic mechanical properties experimental of 32 group cemented backfill were designed at different content of early strength agent?0.0%,0.3%,0.6%,0.9%?,different conservation periods?3d,7d,14 d,28d?,different height of specimens?the static load experimental are 100 mm,the dynamic load experimental are 50mm?.The dynamic load experimental were tested with split Hopkinson pressure bar?SHPB?apparatus.The static load experimental were tested with RMT^-150 rock mechanics testing system.?2?The results of static load experimental were analysed.The compressive strength of backfill has a logarithmic increase with the increase of curing age.Also,the elastic modulus increase with the increase of curing age.But the strain decrease with the increase of curing age.The influence of early strength agent on the mechanical properties of backfill have similar principle at 3,7 days.That is the compressive strength increase,the elastic modulus increase,the strain decrease with the increase of early strength agent content.The maximum of change range of those values between 0.3%content and 0.6%content of early strength agent.The influence of early strength agent on the compressive strength and elastic modulus is more noticeable at 3 days.With the 0.3%,0.6%,0.9%content of early strength agent,the compressive strength of backfill increases 1.3,1.42,1.54 times respectively,the elastic modulus of backfill increases 1.07,1.68,1.84 times respectively.The influence of early strength agent on the mechanical parameters of backfill are not distinct at 14 days.The compressive strength of backfill of the early strength agent filled with 0.6% 0.9% were lower than that of no early strength agent at 28 days.?3?The results of dynamic load experimental were analysed.Generally speaking,the compressive strength of backfill has a logarithmic increase with the increase of strain rate at different strain rate.When the strain rate is less than 10 S^-1,the stability of backfill is good.But the backfill have some damage crack at the strain rate is 25 S^-1.The damage crack split two pieces and crack coalescence led to backfill lose stability when the strain rate is more than 35 S^-1.The influence of incident energy on backfill is similar to the strain rate.The increase relationship between energy absorption of backfill and curing age is logarithmic.The dynamic load strength of backfill has a logarithmic increase with the increase of curing age.The trend of the change of dynamic load strength is similar to static load strength.But the dynamic load strength is higher.The improvement factor of strength is 1.37².35.The influence of early strength agent on the mechanical properties of backfill is similar to static load experimental.That is the dynamic load strength increase,the elastic modulus increase,the energy absorption increas,the peak strain decrease with the increase of early strength agent content.The influence of early strength agent on the mechanical parameters is more noticeable at 3 days.With the 0.3%,0.6%,0.9%content of early strength agent,the dynamic load strength increases 1.23,1.36,1.48 times respectively,the elastic modulus increases 1.33,2.44,3.53 times respectively,the energy absorption increas 1.5,1.92,2 times respectively,the peak strain decreases 1.25,1.28,1.85 times respectively.