Acoustic emission response precursor characterization of cemented tailings backfill at different loading rates

Due to the increase in mining depth and the difference in the advancement speed of the mining face, the mechanical properties of the cemented tailings backfill in the mining void are often affected by a number of factors, such as complex ground stresses and violent mining disturbances. In this paper, the uniaxial compression and acoustic emission(AE) monitoring tests on the tailing sand cemented fill were carried out to analyze the characteristics of the differences in the variation of AE ring counts, acoustic emission energy, RA-AF, R value and b value under different loading rates. The results show that with the increase of loading rate, the AE ringing counts and AE energy are in a decreasing trend as a whole, and the evolution process can be divided into four phases, in which the proportion of events in the III and IV is significantly increased; There are obvious differences in the evolution of RA and AF parameters at different loading rates, but the specimens are all damaged mainly by tensile cracking, and it is noteworthy that the proportion of shear cracking increases significantly with the increase of loading rate; Under different loading rates, the trends of R value and b value are basically the same, showing an increase at the beginning of loading, while in the plastic deformation stage, R value decreases abruptly and then tends to stabilize, and the b value decreases and reaches the minimum in this stage, and then rebounds and fluctuates; the R value of the plastic deformation stage is the same as the b value of the plastic deformation stage. With the increase of loading rate, the sudden change points of R and b values are gradually close to the peak stress point, and the sudden change phenomena of R and b values can be used as the precursor response characteristics of the specimen to occur macroscopic damage. The research content of this paper has a scientific basis for the destabilization damage of mining engineering.