RESEARCH ON DENOISING METHOD FOR MICROSEISMIC SIGNALS OF UNDERGROUND ENGINEERING BASED ON WPD-EMD-WPD

The background noises in microseismic signals have great influences on the first arrival picking, source location, and parameter inversion. Reasonable and effective noise reduction methods are a significant basis for the reliable application of microseismic monitoring technology in engineering construction. In this paper, a noise suppression method based on WPD-EMD-WPD is proposed, and the signal deviation ratio is used to measure the noise reduction effect. In this method, the signal containing noise is denoised by wavelet packet in advance to achieve the first filtering. Then the Empirical Mode Decomposition(EMD)adaptive decomposition is performed on the denoised signal to obtain IMFS. The position of the EMD decomposition component is determined by the correlation coefficient method. Finally, the wavelet packet of the high-frequency component before the boundary component is denoised and reconstructed with the low-frequency component. Wavelet packets, EMD,EMD-WPD, and WPD-EMD-WPD are used for noise Ricker wavelet noise reduction in simulation experiments. By comparing the measurement index, spectrum diagram, and waveform diagram of noise reduction before and after noise reduction, it is found that the noise reduction effect of the WPD-EMD-WPD method is better, and the signal deviation ratio has good correspondence with other noise reduction indices.