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为了研究微地震信号的频率特征,用DB5小波对信号进行5层分解计算显著频率,用窗口傅立叶变换计算瞬时频率,发现频率有衰减趋势。微地震过程中,先产生频率较高的振动,由于岩体阻尼而非面波频散引起振动频率衰减。对微地震信号预分段,用小波提取其频率谱中的频率特征,得到了频率变化的四种趋势。用相邻零点和相邻峰值点法计算信号的半周期,证实了频率存在衰减性,同时发现频率与振幅有关,振幅大(小),频率低(高),这可能是由于岩石的非线性蠕变造成的,可用于研究岩石非线性特性。
In order to study the frequency characteristics of microseismic signals, DB5 wavelet is used to decompose the signals to calculate the significant frequencies in five layers. The window Fourier transform is used to calculate the instantaneous frequencies, and the frequency is found to decay trend. In the process of microseismicity, the vibration with higher frequency is generated first, and the vibration frequency is attenuated due to the rock mass damping rather than the surface wave dispersion. For the pre-segmentation of microseismic signals, the frequency characteristics in the frequency spectrum are extracted by wavelet, and four trends of frequency changes are obtained. The half cycle of the signal is calculated by the adjacent zero point and the adjacent peak point method, which confirms the decay of the frequency. At the same time, it is found that the frequency is amplitude dependent, the amplitude is small and the frequency is low. This may be due to the nonlinearity of the rock Creep caused, can be used to study the nonlinear characteristics of rocks.