花岗岩劈裂破坏电磁-震动有效信号重构与混沌特征

Effective signal reconstruction and chaotic characteristics of electro-seismic signal of granite splitting failure

电磁辐射、震动监测技术广泛应用于地下工程动力灾害的监测预警,对地下工程的安全高效开发具重要意义。深入研究电磁-震动信号有助于推动岩体监测预警技术的发展,然而当前电磁辐射和震动信号(电磁-震动)分析主要集中于信号的相关性和时频特征,对于花岗岩破裂电磁-震动信号的非线性动力特征研究较少,相关特征尚未明确。基于此,利用经验模态信号(EMD)重构和分形理论相结合的方法,分析了花岗岩劈裂破坏电磁-震动信号的混沌特征,揭示了电磁-震动信号非线性动力特征。研究结果表明:花岗岩劈裂破坏产生的电磁辐射与震动信号在时间上具有较好的一致性,劈裂破坏产生的电磁-震动信号频谱集中在中低频段;花岗岩破坏有效电磁辐射信号的盒维数D_(E)=1.600 6,有效震动信号的盒维数D_(A)=1.594 8,两者频率结构特征高度相似;利用EMD分解重构方法可以获得花岗岩破裂有效电磁辐射与震动信号,使用EMD分解重构去除了高频存在的干扰对花岗岩破裂电磁-震动信号中的混沌特征描述更为精准。有效电磁辐射与震动信号包含的低频、大能量信号比原始信号更多,更能表征微小裂纹扩展;重构后电磁-震动信号的不均匀度相较于初始信号整体有明显的上升,不同能量信号出现的频率关系整体出现下降,重构后的有效电磁-震动信号以低频、大能量信号为主,但震动信号的不均匀程度大于电磁辐射。

Electromagnetic radiation and vibration monitoring technologies are widely used in the monitoring and early warning of dynamic disasters in underground engineering,which is of great significance to the safe and efficient development of underground engineering.In-depth study of electro-seismic signals is helpful to promote the development of granite mass monitoring and early warning technology.However,the current analysis of electromagnetic radiation and vibration signals(electro-seismic)mainly focuses on the correlation and time-frequency characteristics of signals.There are few studies on the nonlinear dynamic characteristics of granite fracture electro-seismic signals,and the relevant characteristics are not yet clear.Based on this,this paper uses the combination of empirical mode signal(EMD)reconstruction and fractal theory to analyze the chaotic characteristics of electro-seismic signals of granite splitting failure,and reveals the nonlinear dynamic characteristics of electro-seismic signals.The results show that the electromagnetic radiation generated by granite splitting failure is in good agreement with the vibration signal in time,and the frequency spectrum of the electro-seismic signal generated by splitting failure is concentrated in the middle and low frequency band.The box dimension of the effective electromagnetic radiation signal of granite failure is D_(E)=1.6006,and the box dimension of the effective vibration signal is D_(A)=1.5948,and the frequency structure characteristics of the two are highly similar.The effective electromagnetic radiation and vibration signals of granite fracture can be obtained by the EMD decomposition and reconstruction method.It is more accurate to describe the chaotic characteristics of granite fracture electro-seismic signals by using the EMD decomposition and reconstruction to remove the interference of high frequency.The effective electromagnetic radiation on the vibration signal contains more low-frequency and high-energy signals than the original signal,which characterizes the propagation of small cracks.The non-uniformity of the reconstructed electro-seismic signal is significantly higher than that of the initial signal,and the frequency relationship of different energy signals decreases.The reconstructed effective electro-seismic signal is mainly low-frequency and high-energy signals,but the non-uniformity of the vibration signal is greater than that of electromagnetic radiation.