Abstract: In order to deal with the problem of excessive filling cost caused by conservative design of high stage layered cemented backfill strength,based on the rockfilling physical parameters of Daye Iron Mine,the strength of cemented slicing backfill computer simulations through three mechanics model is done,the study of influence law of filling strength with backfill times and layered structure as influencing factors is conducted,and the mathematical model and reduction coefficient between the strength of cemented backfill and the filling times is obtained.The minimum numerical solution of the cohesion and strength requirements of the middlelayer backfill is obtained by the twosteps numerical simulation search calculation of mining and filling time series based on FLAC3D software.On this basis,the cementsand ratio and the layered structure of the high stage delayed cementing backfill are optimized.The study results is help for reducing the amount of cementing agent and the cost of backfill,which can provide a reference for the structure and strength optimization design of backfill in similar mines.

Key words: filling mining,layered cemented backfill,strength requirement,structure optimization,numerical simulation,high stage