Spectral prediction and control of blast vibrations during the excavation of high dam abutment slopes with millisecond-delay blasting

Abstract

In hydropower projects in Southwest China, large-scale, high-intensity blasts are required to excavate high rock slopes. In these cases, traditional prediction and control methods for blast vibrations are invalid. Thus, a method to predict the time history of blast vibrations on high slopes is proposed, and a blast vibration spectral control scheme based on this method is presented. Additionally, a case study for the abutment slope excavation of the Xiluodu hydropower project is presented. The results indicate that if the delay interval is <20ms or >50ms, a large amount of energy is distributed in the resonant frequency band of the slope; with optimized delay interval of 20–25ms and 45–50ms, the low-frequency compositions of blast vibrations are considerably fewer, and spectral control can be implemented more effectively. Delay intervals of 25 and 50ms are adopted in practice considering the detonator limitation.