Noise reduction method of microseismic signal of water inrush in tunnel based on variational mode method

The extraction of effective signals of microseismic event caused by water inrush in tunnels is an important prerequisite for accurate location of event. In this paper, based on the characteristics of the main frequency components of the tunnel water burst signal, the variational modal method (VMD) with good frequency decomposition ability is adopted to effectively extract the high-frequency components of the water inrush signal. The effective modes are identified by the method of detrend analysis, and the modal decomposition number K is determined. At the same time, the boundary between noise and effective signal is determined. The method proposed in this paper solves the problem that noise in some modal components is mixed with effective signals, and further improves the ability of extracting weak high-frequency signals. Through the analysis of case data, the validity of the research results in this paper is verified, and an effective signal extraction method of tunnel water inrush microseismic event based on VMD-DFA principle is formed.