不同初始缺陷条件下尾矿胶结充填体损伤突变预警分析

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

尾矿胶结充填体的干缩、硬化过程易使内部形成初始缺陷,为研究含不同初始缺陷的尾矿胶结充填体物理、力学和破坏特征,在尾矿胶结充填体中加入不同含量引气剂(AEA)进行模拟充填体的初始缺陷,通过扫描电镜、XRD图谱、单轴压缩和声发射试验进行分析。运用尖点突变模型,根据应力-应变曲线求出不同初始缺陷充填体的突变预警区间,与声发射失稳破坏的前兆信息进行对比验证。结果表明:加入AEA会使充填体内部气泡、孔洞、孔隙增加,导致初始缺陷增加,声发射信号数量大大减少;随着AEA加入,充填体压密阶段与全过程时间占比增加,弹性阶段与全过程时间占比减少,破坏过程中大尺度裂纹数量减少,增加了内部裂纹的无序性,从延-脆性破坏变为延性破坏模式;不同含量AEA充填体突变预警区间与声发射破坏前兆信息相对应,通过突变预警区间可以有效预测不同初始缺陷尾矿胶结充填体的稳定性,为矿山安全预警提供参考。

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.