位置条件对爆破震动信号分析中小波包时频特征的影响

AFFECT OF SITUATION CONDITION ON TIME-FREQUENCY CHARACTERISTICS OF BLASTING VIBRATION WITH WAVELET PACKETS ANALYSIS

爆心至测点的位置条件是影响爆破震动时频分布的主要因素之一。在考虑到段药量变化的情况下,位置条件由比例距离和高差系数来进行量化。运用小波包分析方法对监测获得的爆破震动信号进行时频特征分析,探讨时频分布与比例距离及高差系数之间的关系。试验研究发现,位置条件对震动波形小波包细节信号时频特征的影响主要体现在峰值质点振速、优势频率大小及波形衰减阻尼比的变化上。其中峰值质点振速随比例距离的增加呈指数衰减,其与高差系数的相关规律性不强;优势频率随比例距离增加也呈衰减趋势,高差系数对其有较大影响,但规律不明显;衰减阻尼比在不同的主振频带内与比例距离及高差系数有不同的关系,较低频率部分其阻尼比随着比例距离的增加而增大,较高频率部分则基本保持不变。

Situation condition,referring mainly to the distance between a blasting center and a monitoring point,is one of main influencing factors for the timefrequency characteristics of blasting vibrationConsidering the change of explosive charge weight with delay interval,the situation condition is quantified by two parameters,scaled distance and altitude difference coefficientThrough analyzing the timefrequency characteristics of the measured blasting vibration signals by wavelet packets method,the authors discuss the relation of the timefrequency distribution to scaled distance and altitude difference coefficientIt has been discovered in the experimental investigation that influences of situation condition on the timefrequency characteristics of the detailed signals with wavelet packets analysis is mainly embodied in the changes of peak particle velocity,dominant frequency and attenuation damping ratio of vibration waveform Peak particle velocity decreases exponentially with increasing of the scaled distance,and has a weak correlativity with altitude difference coefficientAlso,dominant frequency decreases with increasing of scaled distance,and is subject to a greater influence of altitude difference coefficient In different dominant frequency bandwidths,attenuation damping ratio has various correlative relations with scaled distance and altitude difference coefficientIn lower frequency bandwidths,attenuation damping ratio increases with scaled distance rise,but it is basically constant in higher frequency bandwidths