Experimental study of characteristics of energy and basic frequency of seismic waves generated by explosion in soil with different coupling media

Coupling media around the explosive source have significant effect on the characteristics of the energy and basic frequency of the seismic wave. In order to improve the quality of seismic wave generated by explosive source in seismic exploration, the influences of the properties of coupling media on the features of seismic wave are studied, in which four kinds of media, such as air, water, fine sand and coarse soil, are used as the coupling media in the field test. The effects of coupling media on the quality of seismic are analyzed by comparing the amplitudes and frequencies of the waves recorded in the explosion test in soil. The frequencies are divided into different frequency bandsthrough the fast Fourier transform (FFT), and the ground vibrations recorded in the range from 5 m to 65 m away from the explosive source are analyzed. It could be found from the experimental results that the seismic wave energy in water as a coupling medium is the highest, especially at the effective frequency band of 25 Hz to 100 Hz; the energy of the wave generated in air comes second. For frequency domain, the highest basic frequency is appeared in water; meanwhile the attenuation of the basic frequency is the slowest. In the coarse soil, the basic frequency is higher in the near field in the range of 25 m. But the basic frequency is reduced with the increase in the distance beyond the range. The experimental study shows that the water could be the better coupling medium, which can be used in exciting the seismic wave by the explosive source to meet the requirement in seismic exploration.