Study On Time-frequency And The Fractal Box Dimension Characteristics Of Open-pit Blasting Vibration Signal From Yongping Copper Mine

Blasting vibration damage control is one of the important research topics about blasting safety technologyat home and abroad, and the blasting vibration signal analysis is the basis of blasting vibration damage control.The instantaneity and complexity of blasting vibration signals and the diversity of the occurrence condition inblasting mediumlead to the blasting vibration randomness is very large. Thus, the extraction of various kinds oftime-frequency characteristics of the measured signal has always been the hot spot of the blasting vibrationsignal processing analysis with difficulty.Wavelet transform is a better popular time-frequency analysis method in blasting vibration signal analysisdomain application. HHT transform is the new effective method for non-stationary signal processing in recentyears. For the further study of blasting vibration signal characteristics and providing a new research idea incontrolling blasting seismic effect, time-frequency and the fractal box dimension characteristics for open-pitblasting vibration signal from yongping copper mine were analyzed based on wavelet transform and HHTmethod. The main research contents and conclusions are as follows:1. Based on wavelet transform theory, to decompose bench blasting vibration signals of open-pit mine,every wavelet component’s frequency spectrum was analyzed and the wavelet component flame maximumspeed and energy distribution characteristics of the relationship was investigated，and each wavelet componentflame maximum speed had a good consistency with the size of the frequency band energy. Meanwhile，the twobench blasting vibration signals frequency band was divided into several series by using wavelet packetdecomposition and obtainded the energy distribution characteristics: the energy of the blasting vibration signalswere mostly concentrated in the below of128Hz, especially in the majority with64Hz, some of the blastingvibration signal energy may be concentrated in a band, but some were within2-3band of energy distribution.2. Based on the HHT analysis method of blasting vibration signal, the fv of bench blasting vibration signalwas divided into several IMF components on the EMD decomposition, and the IMF components’ frequencyspectrum picture was obtainded. Moreover with Hilbert transform, each IMF was transformed and the Hilbertspectrum was obtainded. And, EMD three-dimensional composite image, the picture of Hilbert instantaneousenergy spectrum, energy spectrum, the contour energy spectrum, marginal spectrum and energy spectrum ofthree-dimensional were obtainded by disposing. From these diagrams, the corresponding relation of frequency,amplitude, time and transient energy of the fv signal and the IMF component with its EMD decompositionscales could be reflected.Meanwhile, the difference between the wavelet transform and HHT method in dealingwith the blasting vibration signals were compared.3. The rectangular double-scale fractal box dimension mode was described based on the fractal theory.Through the calculation of bench blasting vibration signals’ fractal box dimension, the laws of the fractal boxdimension between the waveform and spectrum was explored, the fractal box dimension can reflect the turbulence intensity of the signal waveform and the blasting vibration signal frequency composition.Throughfractal box dimension combining with wavelet decomposition and EMD decomposition, the blasting vibrationsignal’s fractal characteristics of all components were discussed, and the trend that the box dimension of thecomponents rising with the increase of its frequency band was obtainded and the components similar with theoriginal blasting vibration signal box dimension had more energy. Fractal box dimension was applied to studyon the blasting vibration signal’ denoises of wavelet.