Study of the effect of loading modes on the acoustic emission fractal and damage characteristics of cemented paste backfill

To investigate the relationship between damage variables and fractal dimensions during the deformation and destruction of tantalum-niobium tailing cemented paste backfill (CPB), uniaxial compression and Brazilian split tests were conducted on tantalum-niobium tailing CPB. The changes in the damage variables and fractal dimensions of the CPB during the damage process were investigated using a damage model based on the acoustic emission (AE) ringing count rate and the calculation of the AE energy rate fractal dimension. During the deformation and destruction of the CPB, the fractal dimensions of the CPB gradually decreased, and the damage variables gradually increased; moreover, the stages of reduction in the fractal dimensions corresponded to the stages of increase in the damage variables. The fractal dimensions of the CPB before deformation and failure did not decrease significantly and gradually tended to converge to a certain value. Under different loading modes, the fractal dimensions of the CPB before deformation and failure were different. The damage variability and energy emitted during the initial loading phase of deformation damage were lower than those during the later phase. Before the damage of the CPB, both the damage variables and energy emitted increased rapidly. For both uniaxial compression and Brazilian split loading, the fractal dimensions of the AE of the CPB gradually approaching a certain value is an important precursor of the overall macroscopic destruction of the CPB. Based on this feature, it can be used to predict and analyze the stability of the tantalum-niobium mine tailing CPB in the underground support roof. (C) 2021 Elsevier Ltd. All rights reserved.