RESEARCH ON TIME-FREQUENCY ANALYSIS ALGORITHM AND INSTANTANEOUS FREQUENCY PRECURSORS FOR ACOUSTIC EMISSION DATA FROM ROCK FAILURE EXPERIMENT
GONG Yuxin1，HE Manchao2，3，WANG Zhenghong1，YIN Yuting1
(1. School of Mathematics and Statistics，South Central University for Nationalities，Wuhan，Hubei 430074，China；2. State Key Laboratory for Geomechanics and Deep Underground Engineering，China University of Mining and Technology，Beijing 100083，China；3. School of Mechanics and Civil Engineering，China University of Mining and Technology，Beijing 100083，China)
Abstract：In order to obtain the instantaneous frequency precursors containing such information as time，frequency，amplitude and dynamical information，which are the basis for rockburst prediction，wave-form based investigation on acoustic emission(AE) was carried out. Taking the uniaxially loaded granite specimen as a practical case，theoretical and computational analyses were conducted on the segmentation of the large AE data，theory and algorithm of the time-frequency transform and optimization of filtering performance for the analysis window functions. Such analytical or computational based outcomes were obtained as the formulas for assessment of temporal and spectral resolutions of the segmented data，principle for optimized segmentation of the large AE data，optimal design of window width and spectral parameters for the analysis window function，and establishment of the comprehensive optimal time-frequency analysis algorithm involving：(1) the optimal segmentation of the large AE data；(2) optimal design of the analysis window function；(3) locating the dominant frequency band using short-time Fourier transform(STFT)；(4) determining exactly the central frequencies for the dominant frequency band using Wigner-Ville distribution(WVD)，and enhancement of the time-frequency contour graphs for a detailed representation of the dynamical information. Results from application of the proposed algorithm in analysis of the case demonstrate that the segmented data sets match well with the dynamical process at which fractures propagate at specific stress level；the increase in frequency localization performance and reduction of spectral leaks；good ability in accurately determining central frequency of the dominant frequency band obtained by STFT and avoiding identification of the“cross terms”in WVD. The instantaneous frequency precursors containing the dynamical information can better describe the precursory information for nonlinear process of the rock failure and provide a new，robust means for rock failure prediction and mechanism comprehension.
宫宇新1，何满潮2，3，汪政红1，尹雨婷1. 岩石破坏声发射时频分析算法与瞬时频率前兆研究[J]. 岩石力学与工程学报, 2013, 32(4): 787-799.
GONG Yuxin1，HE Manchao2，3，WANG Zhenghong1，YIN Yuting1. RESEARCH ON TIME-FREQUENCY ANALYSIS ALGORITHM AND INSTANTANEOUS FREQUENCY PRECURSORS FOR ACOUSTIC EMISSION DATA FROM ROCK FAILURE EXPERIMENT. , 2013, 32(4): 787-799.
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2013, Vol. 32 
