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为寻求岩石临界破坏判据和前兆特征,在粗砂岩单轴压缩声发射(AE)试验的基础上,研究了岩石破坏过程中AE信号频段占比随应力变化特征,重点分析高、低两个特征频段占比随应力变化规律,同时对两个特征频段中不同应力水平下AE幅值关联维数进行计算与分析,并建立了基于频段占比与应力间关系的多频段AE信号主频识别判据模型。研究表明:AE信号频段占比的分布特征能较好地诠释岩石破坏所经历的主要过程;岩石破坏过程中,较低频段AE信号(31.25~46.875 k Hz)占比先减小后增大,较高频段AE信号(140.625~156.25 k Hz)占比先增大后减小。在临界破坏状态下,高、低两个特征频段占比分别出现最大值和最小值,且二者中AE幅值关联维数都下降到最低。通过对特征频段占比与应力之间的耦合分析,利用特征频段占比、AE幅值关联维数的变化可更准确地对岩石临界破坏前兆进行判别和预测。
Based on the uniaxial compression acoustic emission (AE) test of coarse sandstone in order to find the critical damage criterion and precursor characteristics of rock, the change of AE signal frequency band proportion with stress in rock failure process is studied. The frequency bands of the characteristic frequency bands vary with the stress. At the same time, the correlation dimension of the AE amplitude at different stress levels in the two characteristic frequency bands is calculated and analyzed, and the frequency identification of multi-band AE signals based on the relationship between the frequency band ratio and the stress is established Criterion model. The results show that the distribution of AE signal frequency band can well explain the main process of rock failure. In the process of rock failure, the AE signal (31.25 ~ 46.875 k Hz) in the lower frequency band first decreases and then increases, The proportion of AE signal (140.625 ~ 156.25 k Hz) in the higher frequency band first increases and then decreases. Under the condition of critical failure, the maximum and minimum values of the two bands of high and low frequencies respectively appear, and the correlation value of AE amplitude in both is reduced to the lowest. Through the analysis of the coupling between the characteristic frequency band and the stress, the change of the correlation dimension of the characteristic amplitude and the AE amplitude can be used to distinguish and predict the critical damage precursors of the rock more accurately.