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

摘要

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 < 20 ms or > 50 ms, a large amount of energy is distributed in the resonant frequency band of the slope; with optimized delay interval of 20-25 ms and 45-50 ms, the low-frequency compositions of blast vibrations are considerably fewer, and spectral control can be implemented more effectively. Delay intervals of 25 and 50 ms are adopted in practice considering the detonator limitation.