Safety threshold of blasting vibration velocity in foundation excavation of Baihetan super-high arch dam

Blasting damage control is one of the main problems in the dam foundation excavation of Baihetan Hydropower Station, and it is important to study the relationship between the blasting vibration and blasting damage. In this paper, a horizontal presplit blasting experiment was carried out at the dam foundation. By combining vibration monitoring and sonic wave detection before and after blasting, the corresponding relationship between the peak particle velocity (PPV) and the damage degree was established. On this basis, the function of grouting in the blasting excavation was analyzed. The results indicate that grouting is very helpful for the blasting damage control. After grouting, the P-wave velocity of the rock mass is increased by approximately 20%, the blasting damage depth is reduced by approximately 14%, and the safety threshold of the PPV is increased by approximately 25%. Meanwhile, the safety threshold of the PPV is positively correlated with the P-wave velocity of the rock mass. According to the damage control standard and rock mechanical properties, the blasting parameters can be rationally optimized.