Abstract:In order to reasonably quantify the critical strength and curing time range of the backfilling of the first-step goaf in the high-stage post-filling method, with the full tailings of an iron mine as the filling aggregate, the compressive strength test of the tailings cemented backfill under different proportions was carried out, and the strength growth law model of the tailings cemented backfill was established, which based on the energy matching principle, the critical strength and curing time range of the backfilling in the first-step goaf of the mine are quantitatively analyzed. The results show that the curing strength of backfill increases exponentially with the increase of curing age, and the higher the mass concentration, the faster the strength of backfill increases. Slump of filling slurry basically follows the law of exponential decline with the increase of mass concentration, and the effect of cement-sand ratio on slump of filling slurry is closely related to the range of mass concentration; The energy matching coefficient K value is constructed to characterize the relationship between the filling body and the excavated ore body, and the relationship between the K value and the filling body strength and curing time is obtained. Based on that, the critical strength of the filling body on the first-step goaf of the mine is quantitatively analyzed to be 1.9 MPa, the mass concentration of 66% and cement-tailings ratio of 1:4 and 26 days curing time are selected for the engineering application of the iron mine, which shorts the curing age by 2 days than actual recovery time.