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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。
Through the uniaxial loading acoustic emission experiment of siltstone, based on the HHT analysis method, the frequency characteristics of acoustic emission signal during rock rupture process are studied. The results show that HHT is a signal time-frequency analysis method based on principal component analysis, which can determine the primary and secondary components of signals and accurately describe the time-frequency characteristics of the signals by using instantaneous frequency. The time-frequency of acoustic emission signals during the rupture of siltstone Distribution of the three stages, namely, the initial zone, the fluctuation zone, the quiet zone; the main frequency of the acoustic emission signal during the rupture of the siltstone is related to the stress level. Before the rupture of the rock, as the stress level increases, the dominant frequency gradually increases Decrease; the stability of the siltstone ruptures from stable expansion to unstable expansion until the rock ruptures, the high-energy acoustic emission signal shifts from high frequency to low frequency, and the duration increases; the acoustic emission signal during siltstone rupture is suitable for monitoring The frequency band is 20 ~ 120 k Hz.