•  
  •  
 

Rock and Soil Mechanics

Abstract

The blasting induced seismic waves are generally composed of compressional wave (P-wave), shear wave (S-wave), and Rayleigh wave (R-wave), however, wave-type and seismic components are not differentiated in the attenuation law and safety criteria for the current blast vibration studies. In this study, a method of wave-type discrimination is used for the seismic wave prediction based on polarization direction. Using theoretical analysis and numerical modelling, the blasting source characteristics and the radiated wave-types are investigated for different shapes of explosive charge. Combined the results of the site blasting experiments, the wave-type and seismic components induced by three typical blast-holes are analyzed and three blast holes include the single vertical blast-hole, the smooth blast-hole, and the slope pre-splitting blast-hole. The source characteristics and acting mechanism are then discussed for different blast-holes. The dominant wave-type at special location is predicted for three blast types. The research results indicate that the blasting source of the vertical blast-hole can be viewed as a delay superposition of the short explosive column. All the P-, S-, and R-waves contribute to the ground surface vibration from the vertical blast-hole. With the increase of the blasting-target distance, it is found that the S-wave gradually deviates from its dominant radiation direction, while the P-wave mainly contributes to the horizontal radial vibration, and the R-wave dominates the vertical vibration. Because the horizontal smooth blast-hole and the slope pre-splitting blast-hole are both contour blast-holes, the two blast holes have a similar acting mechanism, in which the main acting force is the loading from the normal surface. The S- and R-waves are the dominant seismic wave types within the blasting contour surface, whereas the role of the P-wave is negligible. Besides, the R-wave becomes the dominant wave-type as the blasting center distance increases; however, the contribution of P-wave outside the contour surface cannot be ignored.

Graphic Abstract

Download

Share

COinS