Influences of geo-stress on energy distribution of vibration induced by blasting excavation

Adopting the wavelet packet analysis technique, the energy distribution of the vibration, which was induced in the process of tunnel blasting excavation under the high in-situ stress conditions, was obtained. Analysis on the test data shows that the frequency ranges of the vibration induced by the transient unloading of the in-situ stress(VI) and the vibration induced by blast load(VB) are almost the same, but the proportion of the low frequency energy in VI is higher than that in VB. The effect of the transient unloading depends on the magnitude of the in-situ stress for the transient unloading and the size of the unloading area, both of which are determined by the distribution of the blast holes and explosive circuit.