Effect of Delay Time on Attenuation Law of Blasting Vibration in Hole-by-hole Presplitting
To obtain the optimal delay time of hole-by-hole pre-splitting blasting,based on Ansys/LS-Dyna finite element software,combined with field experiments,this paper studies the vibration attenuation law of hole-by-hole pre-splitting blasting under different delay time,which provides a theoretical basis for practical engineering application.The results showed that compared with the simultaneous initiation,the hole-by-hole initiation effectively reduced the peak particle vibration velocity(PPV),especially in the area near the pre-split trench.As the delay time increased,the K value of the Sadaovsk formula gradually decreased,while the α value did not change much.When the delay time was greater than 0.6T(T was the duration of single-hole blasting vibration),the values of K and α tended to be stable and close to single-hole blasting.The correction coefficient β was inversely proportional to the delay time,and the optimal delay time should be 0.6 T～1.0 T;the vibration reduction rate of the main blasting area after hole-by-hole pre-splitting was greater than that of the simultaneous pre-splitting blasting.
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