Prediction and effect analysis of surface vibration waveform for group hole delay blasting

In order to solve the shortcomings of the existing surface vibration waveform prediction method for group-hole delay blasting, a new method is proposed, and the surface vibration effects of group-hole delay blasting are analyzed. First, the vibration velocity waveform function for single-hole cylindrical charge is obtained by superposing the vibration velocity waveform of spherical charge. Then, using the Blair's nonlinear group-hole superposition theory for reference, the nonlinear superposition of vibration velocity function for single-hole cylindrical charge is realized, and the surface vibration velocity waveform function for group-hole delay blasting is obtained. The vibration velocity waveform predicted by the waveform function is consistent with the measured one in the peak vibration velocity, spectral distribution and duration, which verifies the correctness of the waveform function. The influences of delay time and number of holes on the surface vibration are discussed by using the waveform function. It is found that a reasonable delay time can reduce the peak vibration velocity and make the basic frequency of the vibration deviate from the natural frequency of the protected object, while the number of holes has few influences on the peak vibration velocity and the frequency spectrum. The surface vibration velocity waveform function provides a simple method for waveform prediction in practical engineering, and it is of certain practical value for engineering.