地应力对爆破过程中围岩振动能量分布的影响

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

对高地应力条件下隧洞爆破开挖过程中围岩振动信号进行小波包分析,得到了振动信号不同频带上的能量分布。实测资料分析结果表明,爆破开挖时,初始地应力动态卸载诱发的围岩振动的频率范围和爆破荷载诱发的围岩振动频率范围基本相同,但地应力卸载诱发的振动中,低频能量占较大的比例;开挖面上的卸载应力值的大小和卸载面的大小共同决定卸载效应的强弱,而这两个因素均与开挖面上的炮孔布置和起爆网络的连接有关。

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.