Time Frequency Analysis Of Rock Acoustic Emission Signals

The degeneration of the internal stress,the crack propagation and the elastic energy release are the important mechanisms of the structural destabilization and failure.When the elasticity accumulates to a certain extent and is released instantaneously,it forms the visual material destruction.Therefore,it is very important to study the characteristic parameter extraction of AE signal in this process and the process of the fracture and destabilization of granite in different water states.However,acoustic emission signal is a typical non-stationary signal,which makes the traditional signal processing technology difficult to analyze the acoustic emission signal of rock burst comprehensively and systematically.So,many experts and scholars have studied the problem of the effective analysis method of non-stationary signal.The acoustic emission signals of the failure process were collected through the indoor biaxial loading test of granite specimens with different water content states.First of all,the acoustic emission signals collected by the signal itself contain noise.The Denoising method is more suitable for the acoustic emission signal of rock rupture than the traditional threshold denoising by the wavelet packet coefficients.Secondly,using the full phase spectrum analysis algorithm to analyze different phase spectra of AE signals in different water states,it finds that the linear phase proportion of granite before each stage of large energy point is less than that of the large energy point.The rupture of granite in natural state is more concentrated than the rupture of dry and watery state,and the fast phase type recognition algorithm is found.Thirdly,based on the wavelet packet decomposition and reconstruction algorithm to select the dominant frequency bands of AE signals,the dominant bands of three kinds of granite with different water states are 0~62.5k Hz,and the increase of moisture content decreases.Finally,the time-frequency domain analysis of AE signal is in time-frequency analysis,it is more intuitive to observe the distribution of energy in time and frequency in each period of rock rupture,the Ville distribution is raised,the resolution is increased,and the main rupture occurs in the third and fourth stages of granite.The Ville distribution before the datum points in each stage is larger than the Ville distribution after the Datum point,and the large energy aggregation region is more obvious,and the large energy distribution frequency range before the same datum point in the different water-bearing granite is less than the frequency range after the Datum point.But after the peak energy is greater than the datum point,the energy distribution of three kinds of granite with different water content decreases with the increase of water content.Although the experiment under laboratory conditions is different from that of the engineering,it is very important to monitor and warn the rock failure in same.