Acoustic Emission (AE) waveforms contain information on microscopic structural features that can be related with damage of coal rock masses. In this paper, the Hilbert-Huang transform (HHT) method is used to obtain detailed structural characteristics of coal rock masses associated with damage, at different loading stages, from the analyses of the characteristics of AE waveforms. The results show that the HHT method can be used to decompose the target waveform into multiple intrinsic mode function (IMF) components, with the energy mainly concentrated in the C₁–C₄ IMF components, where the C₁ component has the highest frequency and the largest amount of energy. As the loading continues, the proportion of energy occupied by the low-frequency IMF component shows an increasing trend. In the initial compaction stage, the Hilbert marginal spectrum is mainly concentrated in the low frequency range of 0–40 kHz. The plastic deformation stage is associated to energy accumulation in the frequency range of 0–25 kHz and 200–350 kHz, while the instability damage stage is mainly concentrated in the frequency range of 0–25 kHz. At 20 kHz, the instability damage reaches its maximum value. There is a relatively clear instantaneous energy peak at each stage, albeit being more distinct at the beginning and at the end of the compaction phase. Since the effective duration of the waveform is short, its resulting energy is small, and so there is a relatively high value from the instantaneous energy peak. The waveform lasts a relatively long time after the peak that coincides with failure, which is the period where the waveform reaches its maximum energy level. The Hilbert three-dimensional energy spectrum is generally zero in the region where the real energy is zero. In addition, its energy spectrum is intermittent rather than continuous. It is therefore consistent with the characteristics of the several dynamic ranges mentioned above, and it indicates more clearly the low-frequency energy concentration in the critical stage of instability failure. This study well reflects the response law of geophysical signals in the process of coal rock instability and failure, providing a basis for monitoring coal rock dynamic disasters.

声发射 (AE) 波形包含有关可能与煤岩体损坏相关的微观结构特征的信息。本文采用希尔伯特-黄变换(HHT)方法，通过声发射波形特征分析，获得不同加载阶段与损伤相关的煤岩体的详细结构特征。结果表明，HHT方法可以将目标波形分解为多个本征模态函数(IMF)分量，能量主要集中在C ₁ – C ₄ IMF分量中，其中C ₁组件具有最高的频率和最大的能量。随着加载的继续，低频IMF分量所占的能量比例呈增加趋势。在初始压实阶段，希尔伯特边缘谱主要集中在 0-40 kHz 的低频范围内。塑性变形阶段与 0-25 kHz 和 200-350 kHz 频率范围内的能量积累有关，而不稳定破坏阶段主要集中在 0-25 kHz 频率范围内。在 20 kHz 时，不稳定损伤达到最大值。每个阶段都有一个相对清晰的瞬时能量峰值，尽管在压实阶段的开始和结束时更加明显。由于波形的有效持续时间短，其产生的能量很小，所以从瞬时能量峰值有一个相对较高的值。波形在与故障重合的峰值之后持续相对较长的时间，这是波形达到其最大能量水平的时期。希尔伯特三维能谱在真实能量为零的区域一般为零。此外，它的能谱是间歇性的而不是连续的。因此与上述几个动态范围的特点是一致的，更清楚地表明了失稳失效临界阶段的低频能量集中。该研究较好地反映了煤岩失稳破坏过程中地球物理信号的响应规律，为煤岩动力灾害监测提供了依据。波形在与故障重合的峰值之后持续相对较长的时间，这是波形达到其最大能量水平的时期。希尔伯特三维能谱在真实能量为零的区域一般为零。此外，它的能谱是间歇性的而不是连续的。因此与上述几个动态范围的特点是一致的，更清楚地表明了失稳失效临界阶段的低频能量集中。该研究较好地反映了煤岩失稳破坏过程中地球物理信号的响应规律，为煤岩动力灾害监测提供了依据。波形在与故障重合的峰值之后持续相对较长的时间，这是波形达到其最大能量水平的时期。希尔伯特三维能谱在真实能量为零的区域一般为零。此外，它的能谱是间歇性的而不是连续的。因此与上述几个动态范围的特点是一致的，更清楚地表明了失稳失效临界阶段的低频能量集中。该研究较好地反映了煤岩失稳破坏过程中地球物理信号的响应规律，为煤岩动力灾害监测提供了依据。这是波形达到其最大能量水平的时期。希尔伯特三维能谱在真实能量为零的区域一般为零。此外，它的能谱是间歇性的而不是连续的。因此与上述几个动态范围的特点是一致的，更清楚地表明了失稳失效临界阶段的低频能量集中。该研究较好地反映了煤岩失稳破坏过程中地球物理信号的响应规律，为监测煤岩动力灾害提供了依据。这是波形达到其最大能量水平的时期。希尔伯特三维能谱在真实能量为零的区域一般为零。此外，它的能谱是间歇性的而不是连续的。因此与上述几个动态范围的特点是一致的，更清楚地表明了失稳失效临界阶段的低频能量集中。该研究较好地反映了煤岩失稳破坏过程中地球物理信号的响应规律，为煤岩动力灾害监测提供了依据。它的能谱是间歇性的而不是连续的。因此与上述几个动态范围的特点是一致的，更清楚地表明了失稳失效临界阶段的低频能量集中。该研究较好地反映了煤岩失稳破坏过程中地球物理信号的响应规律，为煤岩动力灾害监测提供了依据。它的能谱是间歇性的而不是连续的。因此与上述几个动态范围的特点是一致的，更清楚地表明了失稳失效临界阶段的低频能量集中。该研究较好地反映了煤岩失稳破坏过程中地球物理信号的响应规律，为煤岩动力灾害监测提供了依据。