岩石破坏声发射信号的CEEMDAN−小波变换降噪法

CEEMDAN Wavelet Transform Denoising Method for Acoustic Emission Signals of Rock Failure

  • 摘要: 岩石材料破坏过程中产生的声发射信号具有高度随机性、信噪比低且易受环境干扰,这给实验中信号特征提取与定量分析带来了显著挑战。为此,本文提出了一种基于自适应噪声的完全集成经验模态分解与小波变换相结合的降噪方法。首先,生成叠加白噪声的模拟AE信号,模拟实验常见噪声环境。采用完全集成经验模态分解算法对含噪信号进行自适应分解,获得多阶本征模函数,有效抑制了传统经验模态分解和集成模态分解中的模态混叠问题。通过与原始信号的相关性分析,筛选出噪声主导分量,并利用小波变换进一步降噪。随后,方法应用于在受控条件下对花岗岩圆柱试样进行单轴压缩实验所采集的声发射信号数据,通过信噪比、均方根误差及皮尔逊相关系数等量化指标进行评估。结果表明,完全集成经验模态分解−小波方法显著提升了信号质量:模拟信号信噪比由14.86 dB提高至15.31 dB(提升3%),均方根差由0.0971降至0.0877(降低9.3%);实验声发射信号信噪比由9.06 dB提升至9.69 dB(提升6.9%),均方根差由0.0032降至0.0011(降低65.6%),相关系数由0.905增至0.960。上述结果验证了该方法在噪声抑制和信号特征保持方面的优越性,为岩石实验中声发射信号的高精度分析提供了有效手段。

     

    Abstract: Acoustic emission (AE) signals generated during the failure of rock materials were typically characterized by high randomness, low signal−to−noise ratio (SNR), and significant susceptibility to environmental interference, which posed considerable challenges to accurate feature extraction and quantitative analysis in rock mechanics research. In this study, a robust denoising method based on Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) combined with wavelet transform was developed and validated. Synthetic AE signals with added white noise were generated to simulate noisy laboratory environments, and the CEEMDAN algorithm was applied to adaptively decompose these signals into multiple intrinsic mode functions (IMFs), effectively addressing the modal aliasing problem commonly found in empirical mode decomposition (EMD) and ensemble EMD (EEMD). Each IMF was evaluated for its correlation with the original signal, and noise−dominated components were denoised using wavelet transform; the db4 wavelet basis function was selected after comparative analysis of SNR and root mean square error (RMSE). The method was further applied to AE data collected from uniaxial compression tests on granite samples under controlled laboratory conditions, with signal acquisition performed by a multi−channel system at high sampling rates, and all processing and analysis was carried out in MATLAB. The results show that, compared to conventional EMD− or EEMD−based denoising methods, the CEEMDAN−wavelet approach significantly improves signal quality: for simulated AE signals, the SNR increases from 14.86 dB to 15.31 dB (a 3% improvement) and the RMSE decreases from 0.0971 to 0.0877 (a 9.3% reduction); for experimental AE signals, the SNR increases from 9.06 dB to 9.69 dB (a 6.9% improvement), the RMSE drops from 0.0032 to 0.0011 (a 65.6% reduction), and the Pearson correlation coefficient rises from 0.905 to 0.960. These results confirm that the proposed method achieves superior noise suppression while preserving the essential time−frequency characteristics of AE signals, provides practical value for both laboratory and field applications in geotechnical engineering and structural health monitoring, and future work will focus on integrating adaptive parameter optimization and deep learning approaches to further improve the automation and generalizability of AE signal denoising under complex geological conditions.

     

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