The utilization of solid waste such as tailings and smelting slag generated during the ore dressing and smelting process as filling materials in underground goaf is of great significance for achieving the utilization of mining solid waste.In this paper,different proportions of smelting slag and total tailings were used as raw materi-als to prepare backfill specimens,and uniaxial compression tests were conducted.The variation law of the strength of the backfill under different conditions of smelting slag content,mass concentration,and cement-sand ratio was explored.The influence characteristics of the coupling effects of various factors on the strength of the backfill were analyzed using the response surface method.The experimental results showed that,with other conditions un-changed,the addition of smelting slag to some extent reduced the uniaxial compressive strength of the backfill,and the reduction in the 28 day strength value was greater than that in the 7 day strength value.When the mass concentration was increased from 74％to 78％,under the conditions of cement-sand ratios of 1∶4,1∶6,and 1∶12,the growth rates of the 7 day compressive strength of the backfill reached their maximum values,which were 79.7％,92％,and 121％respectively.When the mass concentration and curing age were kept constant,the uni-axial compressive strength of the backfill specimens showed a clear downward trend as the cement-sand ratio de-creased.Based on the single-factor analysis,the significant influencing factors on the uniaxial compressive strength were found to be in the following order:cement-sand ratio,mass concentration,and smelting slag con-tent.The interaction analysis revealed that the cement-sand ratio and mass concentration had the most signifi-cant impact on the uniaxial compressive strength of the specimens.The optimal proportion of the filling slurry was selected as a smelting slag content of 30％,the mass concentration of 78％,and cement-sand ratio of 1∶4 through the regression model.
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