Abstract: Backfill mix ratio changes greatly among different stopes during the test running of backfill system, thus, accurate control of the backfill strength of particular stopes plays an important role in the safety of mining in adjacent stopes, which is also a general technical problem. In this paper, L25 (56) orthogonal design was applied to conduct 25 laboratory mix tests in the backfill mix experiment, and the backfill strengths at different curing ages were tested. Meanwhile, EXCEL and SPSS were used together to present the regression equations of backfill strength and the slurry density, cement dosage, and ratio of artificial aggregate and tailings, respectively. Based on the statistics of 136 kinds of mix ratio, including the backfill strength test results in laboratory and the actual measured values in backfill application, the strength reduction factor of the two results was obtained. Based on the regression equations and strength reduction factor mentioned above, the backfill strength of more than 200 backfill mix ratio access were calculated under the test running period of backfill system. The analysis method introduced in this paper is applicable to calculate backfill strength with different mix ratio, and is highly adaptable and practical for similar mines.

Key words: backfill mix ratio, multivariate non-line regressio, estimation and evaluation of underground backfill strength