基于CEEMDAN-INHT的地下洞室爆破振动时频分析应用研究

Application of Time-frequency Analysis of Blasting Vibration of Underground Cavern based on CEEMDAN-INHT

爆破地震波信号采集会因监测环境、测试系统等因素导致实测信号中混有噪声,噪声的存在将导致信号希尔伯特-黄变换(Hilbert-Huang Transform,HHT)时频分析结果失真。原因有二:其一是经验模态分解(Ensemble Empirical Mode,EMD)处理含噪爆破地震波信号会得到具有模态混淆现象的固有模态函数(Intrinsic mode function,IMF)分量;其二是Hilbert变换受Bedrosian定理的约束在处理模态混淆分量时会产生负值瞬时频率,从而造成巨大的分析误差。为获得真实的爆破振动属性需对HHT进行改进,在EMD中添加自适应噪声信号得到自适应补充集合经验模态分解(Complete Ensemble Empirical Mode Decomposition with Adaptive Noise,CEEMDAN)算法;再对CEEMDAN得到的IMF进行归一化Hilbert变换,得到改进归一化Hilbert变换(Improved Normalized Hilbert Transform,INHT)。通过上述两步可建立CEEMDAN-INHT时频分析算法,为验证该算法可有效提高含噪爆破地震波振动信号时频分析精度,进行HHT和CEEMDAN-INHT含噪仿真振动信号时频分析对比研究。最后将CEEMDAN-INHT用于某地下洞室爆破地震波信号时频分析中,发现该算法能有效克服EMD固有的模态混淆现象,同时得到反映真实爆破振动属性的时-频-能特征参数,对从频率-能量的角度进行洞室爆破开挖共振分析,实现爆破地震波危害控制具有一定的现实意义。

The seismic wave signal acquisition will result in the mixed noise in the measured signal due to the monitoring environment,test system and other factors,and the existence of noise will lead to the distortion of the time-frequency analysis results of the signal Hilbert-Huang Transform.There are two reasons.One is that the empirical mode decomposition(EMD)algorithm will obtain the intrinsic mode function(IMF)component with modal confusion phenomenon when processing the blasting seismic wave signal containing noise;The other reason is that because the Hilbert transform is constrained by the Bedrosian theorem,which will produce negative instantaneous frequencies when dealing with modal confusion components.These lead to huge analytical errors.In order to obtain real blasting vibration properties,HHT should be improved.Complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN)can be obtained by adding adaptive noise signal to EMD.Then normalized Hilbert transform is per-formed on the IMF obtained by CEEMDAN,and an improved normalized Hilbert transform(INHT)is obtained.Through the above two steps,the CEEMDAN-INHT time-frequency analysis algorithm can be established.In order to verify that the algorithm can effectively improve the time-frequency analysis accuracy of the noise-containing blasting seismic wave vibration signal,a comparative study on the time-frequency analysis of the HHT and CEEMDAN-INHT noise-containing simulated vibration signals is carried out.Finally,CEEMDAN-INHT is used in the time-frequency a-nalysis of blasting seismic wave signals in an underground cavern,and it is found that the algorithm can effectively o-vercome the inherent mode confusion of EMD,and at the same time obtain the time-frequency-energy characteristic parameters reflecting the real blasting vibration attributes.It is of practical significance to carry out resonance analy-sis of blasting excavation in caverns from the perspective of frequency and energy,and to realize blasting seismic wave hazard control.