ENERGY ANALYSIS ON BLASTING VIBRATION SIGNAL AT DAMAGE PROCESS OF SURROUNDING ROCK ROOF

The similar model experiment was carried out to simulate the whole process of damage development from stability to roof of metal mine laneway falling in this paper. Fiber bragg grating sensors installed in bolt were used to record the response signal of complete roof and damage roof under different confining pressure and different vibration intensity, and wavelet transform was used to extract vibration response signal of the band energy distribution characteristics. Under the different confining pressure, the frequency band energy of complete roof presents the same trend, which couldn't be significantly affected by confining pressure. And total energy will increase with the increase of confining pressure. Finally, according to the result of the indoor experiment, based on the view of energy band, the transient signal evaluation system under different damage condition was established using mathematics software Matlab, and a serial of continuous signal were analyzed. The vibration response signal energy of damage roof is influenced by developed fracture. Compared with the complete roof, there is an obvious band cusp that the energy peak moves from high frequency to low frequency. Based on roof stability analysis method of wavelet frequency band energy, the propagation of blasting vibration wave is affected seriously by rock damage. After the wavelet decomposition of blasting vibration signal, the energy attenuation extent of blasting signal can be used to determine that there is damage or not in rock roof. The variation characteristics of frequency band energy ratio of wavelet decomposition beta can be termed as the criterion to determine there is crack development or not. The normalized energy ratio of frequency band gamma can be more suitable for determining the crack development degree, which provides a reliable method for stability monitoring of metal mine laneway roof.