Analysis of blasting vibration duration and optimizing of delayed time interval for millisecond blasting

Duration of blasting vibration and delayed time interval of millisecond blasting are respectively an important indicator for assessing and controlling blasting hazards. It is therefore of great necessity to explore the factors that may influence the duration and the ways that can optimize the interval. In the present work, combined with dimensional analysis, we examined the factors influencing the duration arrived at a formula for predicting the blasting vibration duration, whose linear correlation reached 89.7%. Based on the linear superposition theory of seismic wave, the reasonable range of delayed time interval with different distances between the blasting source and the measuring point was obtained using MATLAB7.0. The result shows that there is close correlation between the signal energy and the duration of blasting vibration, the accuracy of prediction can be improved by introducing the signal energy into the predictive formula, the duration is negatively related to the proportional velocity and positively related to the proportional charge weight, and the reasonable range of the delayed time interval between the blasting holes is not always a specific value but may be one or more time intervals, which are determined by different distances between the explosion source and the measuring point. The application of the formula in actual engineering shows that our predictive formula and optimization for millisecond blasting are highly practicable. © 2016, Editorial Board of EXPLOSION AND SHOCK WAVES. All right reserved.