通过对砂岩岩石试样开展单轴加载压缩下的声发射试验，测试岩石试样在单轴多级加载条件下受力变形全过程的声发射参数，建立时间−荷载−声发射参数关系曲线，分析岩石变形破坏全过程的声发射特征及变化情况，对岩石变形破坏过程声发射特征的自相关系数和方差变异性进行深入分析，揭示岩石变形破坏的临界慢化现象，探索岩石临界破坏的声发射前兆表征。研究结果表明：（1）岩石在逐级加载过程中产生明显的声发射现象，声发射振铃计数随着加载级数增加越来越高，在岩石试样破坏时刻达到最高；（2）利用声发射RA（上升时间/峰值幅度）与AF（平均频率）特征分析，岩石试样在整个过程中以张拉破裂为主，加载后期剪切破裂逐步增多；（3）通过声发射振铃计数率、上升时间、峰值频率、RA主要特征时间序列的方差和自相关分析，发现其分析结果均在岩石破坏前存在突变性，即表明出明显的临界慢化现象，可作为岩石破坏灾变的前兆特征；（4）峰值频率和RA的方差变异可作为岩石损伤破坏的关键前兆指标。鉴于此，将临界慢化现象分析用于脆性岩石破坏过程的研究，对深入认识岩石临界破坏状态和灾变前兆具有非常重要的科学价值和实用意义。The acoustic emission (AE) test of sandstonerock sample under uniaxial multi-step loading compression were carried out

andthe AE signals were observed. The relationship curves of time-stress-AEparameters were established

and the characteristics and evolution laws of AEduring the entire loading were analyzed accordingly. With the aim to reveal thecritical slowing down phenomenon of rock deformation and failure

theautocorrelation coefficient and variance of AE parameters versus time wereanalyzed in-depth. The results demonstrate that: (1) the rock produces obviousacoustic emission during the multi-step loading process

and the acousticemission ringing count becomes higher and higher as the loading levelincreases

and reaches the highest at the moment of failure of the rock sample;(2) the characteristics of acoustic emission RA(rise time/peak amplitude)-AF(averagefrequency) indicate that the tensile cracking prevails in the whole loading process

and the shear cracking gradually increases in the later stage of loading; (3) thevariance and autocorrelation coefficient of parameters such as AE ringingcount

rise time

peak frequency

and RA suddenly increase before thecatastrophic failure of rock sample

which indicates that the obvious criticalslowing phenomenon appears before rock failure; (4) the variance of peakfrequency and RA can be used as key precursor indicators of rock damage andfailure. In view of this

applying the analysis of the critical slowingphenomenon to brittle failure process of rock has very important scientificvalue and practical significance for in-depth understanding of the damage stateand the precursors of catastrophic failure of rocks.