为研究冲击倾向性煤单轴压缩过程中不同损伤程度声发射分形特征，对冲击倾向性煤进行了单轴压缩试验，基于声发射振铃次数损伤模型和声发射参数时间序列分形维数计算模型，对煤样破坏过程中的损伤演化和不同损伤程度分形维数进行了研究。研究表明：煤样有大破裂产生时，声发射会出现阶段性增高的现象，较大振铃次数的产生是裂纹扩展、集聚过程中能量释放的结果，冲击煤声发射活动频发大都发生在应力应变全过程的后期；煤样的损伤应变过程可分为3个阶段：初始损伤阶段，损伤演化阶段、损伤持续增长阶段，各阶段的声发射振铃次数占比分别为1.61%、14.83%、83.56%，冲击煤损伤持续增长阶段的时间占比少，但声发射振铃多。随着煤样损伤程度的增加，声发射分形维数先增大，当煤样损伤程度达到30%后突然下降，然后保持波动上升，在煤样损伤程度达到80%时，达到局部峰值后，发生突降，整体变化趋势呈现倾斜的“M”型。分形维数达到峰值后发生突降的现象可作为煤样失稳破坏的前兆信息。

In order to study the fractal characteristics of acoustic emission with different damage degrees in the uniaxial compression process of coal samples with impact tendency. the uniaxial compression test is carried out on the impact-prone coal. the damage model of acoustic emission ringing count and the fractal dimension calculation model of the time series of acoustic emission parameters are used to study the damage evolution in the process of coal sample failure and the fractal dimension of different damage degrees. The research shows that whenever there is a large rupture of coal samples,the acoustic emission will increase gradually. The generation of large ringing count is the result of energy release during crack propagation and aggregation. Most of the frequent acoustic emission phenomena of impact coal occur in the later stage of the whole process of stress-strain; the damage strain process of coal samples can be divided into three stages:initial damage stage,damage evolution stage,and continuous damage growth stage. The acoustic emission ringing counts of each stage are 1.61%,14.83%,and 83.56% respectively. The duration of the sustained growth stage of the coal impact damage is less,but the acoustic emission ringing is more;as the degree of coal sample damage increases,the fractal dimension of acoustic emission increases first. When the damage of coal sample reaches 30%,it suddenly drops,and then keeps fluctuating. When it reaches 80%,after reaching the local peak,a sudden drop occurred and the overall trend showed a tilted "M" shape. The phenomenon that the fractal dimension reaches a peak and then a sudden drop can be used as a precursor to the instability of the coal sample.

0 引言

1 声发射试样制备与试验系统

2 声发射试验结果及分析

3 煤样损伤声发射分形特征

   3.1 煤样声发射损伤特征

   3.2 煤样声发射分形特征

4 讨论

   4.1 煤样声发射分形演化规律

   4.2 煤样破坏声发射分形前兆信息

5 结论