基于HHT的粉砂岩破裂声发射信号频率特性研究

通过对粉砂岩进行单轴加载声发射实验,基于HHT分析方法,研究岩石破裂过程的声发射信号频率特性。研究结果表明:HHT是一种基于主成分分析的信号时频分析方法,可以确定信号的主次成分,用瞬时频率来精确描述信号的时频特性;粉砂岩破裂过程中声发射信号的时频分布有3个阶段,即初始区、波动区、沉寂区;粉砂岩破裂过程中声发射信号的主频与所处的应力水平有关,在岩石破裂前,随着应力水平的提高,主频逐渐降低;粉砂岩破裂过程中,从裂纹稳定扩展到不稳定扩展,直到岩石破裂,高能量声发射信号由高频率向低频率转移,且持续的时间增加;粉砂岩破裂过程中声发射信号适宜监测频段为20~120 k Hz。

Frequency characteristics of acoustic emission signal during rupture process of siltstone based on HHT

By the uniaxial compression tests of siltstone samples, frequency characteristics of acoustic emission (AE) signals in the failure process of siltstone rock were investigated based on HHT analysis. The results show that HHT is a kind of signal time-frequency analysis method based on principal com-ponent analysis, which can determine the major and minor components of the signals, and precisely de-scribe the time-frequency characteristics of the signal with instantaneous frequency. The time-frequency distribution of AE signal of siltstone can be divided into three stages during rupture process:initial zone, wave zone, and quiet zone. Main frequencies of AE signals during rupture process of siltstone samples are associated with stress levels, that is, main frequency decreases with the increase of stress level be-fore siltstone failure. From the stable extension of crack to unstable extension, until the rock failure, high energy AE signals transfer from high frequency to low frequency, and its duration increases. Ap-propriate monitoring bands of AE signals during siltstone rupture process is 20-120 kHz.