Time-frequency analyses of blasting vibration signals in single-hole blasting model experiments

Abstract

With common horseshoe cavern in underground engineering as the prototype, three single-hole blasting model experiments have been carried out. And coupled SPH-FEM approach is adopted for analyzing the limit effect of pre-excavated horseshoe cavern on blasting crater. During the experiment, the blasting vibration signals on the top surface of cemented sand model have been recorded. Then Hilbert-Huang transform has been applied to analyzing the time-frequency characteristics of recorded blasting vibration signals. Both experiment results and numerical cases indicate that the range of blasting crater is controlled effectively by pre-excavating horseshoe cavern, and the limit effect of pre-excavating on blasting crater has a close connection with its length. Moreover, the 50 mm pre-excavated horseshoe cavern presents an amplification effect in blasting vibration effect both along the blasthole direction and perpendicular to the blasthole direction, and it also demonstrates a weaken effect in the main blasting vibration frequency of vertical blasting vibration signal. HHT analyses of vertical blasting vibration signals show that single-hole blasting vibration signals present a centralized distribution in time domain and an uneven distribution in frequency domain. The dominant energy of blasting vibration signal is distributed in several IMF components, where main blasting vibration frequency locates. When cutting the charge, the blasting vibration effect will be reduced, while the main blasting vibration frequency of blasting vibration signal will be increased.