Abstract: Cemented backfills were produced by taking Lilou iron ore tailings as raw material and cement as cementing material.The physical and chemical parameters and the uniaxial compressive strength of Lilou tailings were measured.The relationship of the cemented backfills' strength with slurry concentration,cement-sand ratio and curing age were studied and the sensitivity was analyzed to these impact factors.The strength of the cemented backfills follows a linear growth with slurry concentration,but an exponential growth with cement-sand ratio and curing age.Moreover,the sensitivity of the backfills' strength to cement-sand ratio is the highest,but is the weakest to slurry concentration.In engineering application,the core strength derived from six large filling stopes was analyzed.The underground core strength was above 1.59 MPa higher than laboratory test blocks.In order to satisfy the strength of different depth,it is suggested that filling ratio should be reduced from1:6 to 1:8 at 20～50 m segment,thus lowering the filling costs.

Key words: Cemented backfill, Sensitivity analysis, Strength,Cement-sand ratio