毫秒延时爆破作用下岩体的受迫振动分析

Forced vibration analysis of rock mass under millisecond delay blasting

爆破振动的频谱特性分析是爆破振动控制的基础。通过白鹤滩水电站坝基爆破开挖实测爆破振动数据,利用MATLAB进行频谱分析。结果表明,在相同段别雷管的延迟爆破作用下,利用多参考点复指数法处理爆区两侧的数据,得到的爆破振动频率为两组谐振频率,说明岩体的振动为受迫振动。且两组谐振频率的大小不相等,通过数值计算与分析得到,这是由于运动爆源在爆破地震波的传播过程中产生多普勒效应,使谐振频率因震源相对运动而发生偏移。反之,数据处理结果也同时验证了在考虑多普勒效应的情况下,利用模态识别方法精确计算爆破振动谐振频率的可行性。据此,以毫秒延时起爆产生的振动频率作为控制基频,再利用多普勒效应产生的频率偏移,实现爆源周围的频率定向调控及爆破振动主动控制。

The frequency spectrum analysis of blasting vibration is the basis of blasting vibration control.Based on the blasting vibration data of the dam foundation blasting excavation of Baihetan hydropower station,the frequency spectrum analysis is carried out by means of MATLAB.Under the action of delayed blasting of the same segment,the data at both sides of the detonation zone are processed by the prony-reference complex exponential method.The results show that the vibration frequencies are two sets of resonant frequencies,and the vibration of rock mass is a forced one.The two groups of resonant frequencies are not equal.Through numerical simulation and analysis,it is found that the resonant frequency is shifted due to the Doppler effect which is generated by the relative motion of the seismic source.On the contrary,the data processing results also verify the feasibility of using the modal identification method to accurately calculate the resonance frequency of blasting vibration in the case of Doppler effect.Based on this,the vibration frequency of delayed detonation is used as the fundamental one,and then the frequency shift generated by the Doppler effect is used to achieve the directional frequency alteration and vibration control around explosive sources.