【摘要】 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。更多还原

【Abstract】 For exploring the frequency features of microseismic signals,the frequency spectrum of the signals was obtained with DB5 in 5 levels,and the instantaneous frequency of the signals was achieved with the windowed Fourier transform.Tendency of frequency attenuation was found.High frequency vibrations did occur early in the microseism,and then the frequency was attenuated because of the damping of rock but not by the frequency dispersion of surface waves.The signals were divided into segments and the frequency spectra were got and the frequency features were achieved and 4 types of variation of frequency were found.Half-period of microseismic signals was gained through computing the intervals of adjacent zeros or adjacent peaks of microseismic signals and the tendency of frequency attenuation was found too.The frequency might correlated to the amplitude.Sometimes the larger(smaller) the amplitude,the lower(higher) the period.The relativity of frequency and amplitude might be caused by the nonlinear creep of the rock and it might be a method of studying nonlinear characteristics of rock.更多还原