Early warning analysis of damage mutation in tailings cemented backfill under different initial defect conditions

The drying and hardening process of the tailings cemented filler is prone to initial defects such as air bubbles，holes and micro-cracks within the filler. To study the physical and mechanical properties and damage precursor characteristics of different initial defect-filled bodies，different levels of air-entraining agents(AEA) are added to the cemented filler to simulate the initial defects in the tailings cement during the drying and hardening process. SEM，XRD mapping，uniaxial compression and acoustic emission tests are applied to the analysis. Using the cusp mutation model，the mutation warning intervals for different initial defect-filled bodies are derived from the stress-strain curves and compared with the precursor information for acoustic emission destabilisation damage. The results show that the addition of AEA can increase the bubbles，pores and porosity within the filler，leading to an increase in initial defects and a significant reduction in the number of acoustic emission signals. With the addition of AEA，the proportion of time between the compacting phase and the full process of the filling increases，the proportion of time between the elastic phase and the full process decreases，the number of large-scale cracks during damage decreases，and the disorder of internal cracks increases，transforming ductile-brittle damage into ductile damage. The mutation warning interval of AEA fillers with different content is consistent with the information on acoustic emission damage precursors，and the mutation warning interval can effectively predict the destabilization damage of tailings colluvial fillers with different initial defects，providing a reference for mine safety early-warning. © 2023 Academia Sinica. All rights reserved.