水平光面爆破激发地震波的成分及衰减特征

Components and attenuation of seismic waves induced by horizontal smooth blasting

借助极化偏振分析方法,针对一组现场爆破实验,分析了水平光面爆破激发地震波的成分构成及特性,比较了不同波的衰减特征及各自对爆破振动的影响,并探讨了水平光面爆破的内在力学机理。结果表明,爆破振动中不同波的相对量值及主导波的类型均会随测点位置的改变而变化,爆源特性和沿传播路径的不同衰减共同决定波的成分构成及演化,各测点的优势振动方向也与波的成分构成密切相关。对于水平光面爆破,在光爆孔平面上,P波的影响可忽略,S波主要在竖直向振动,R波对水平及竖直向的振动均有贡献,其中水平向的振动主要由R波引起,而S波的竖直向振速在近区远高于R波,但归因于S和R波的不同衰减,R波在距离爆源22.5 m/kg^1/2(58~67 m)处开始主导竖直向的振动;在光爆孔平面外,P波的影响不可忽略,且在特定位置会成为优势波型。

In this paper, using polarization analysis, we characterized the seismic waves induced by the horizontal smooth blasting in a group of onsite blasting experiments, presenting interpretation of wave components and offering comparison of attenuation characteristics and evaluation of the influences of different waves. We also examined the inherent mechanical mechanism of the horizontal smooth blasting under some simplifications. The results show that the proportion of different waves and the dominant wave type both vary with the relative location of interest, and the dominant motion direction at a specific position closely correlates with the wave components. The pattern of the blasting source and the different attenuation characteristics jointly determine the wave components and their evolutions. For the horizontal smooth blasting, only S and R waves are included on the same plane of smooth blastholes, while the P wave component is negligible. The horizontal vibration is mainly caused by the R wave, while the S wave mainly vibrates in the vertical direction and its vertical velocity in the near field is much higher than that of the R wave. However, the R wave still dominates the vertical vibration if the scaled distance exceeds 22.5 m/kg^1/2(58-67 m), due to the different attenuation speeds of S and R waves. As for the seismic waves outside the same plane of smooth blastholes, the influence of the P wave cannot be ignored and it might become the dominant wave type somewhere. This study can help to enhance the understanding of blast-induced seismic waves.