Study on Blasting Vibration Control Benefits of Damping Holes in Parallel Adjacent Tunnels

The blasting operation of newly-built tunnel has a significant impact on the adjacent existing tunnel. In view of the universality of the damping hole, the damping hole is selected as a means of vibration reduction, but the effect of the damping hole in the adjacent tunnel needs to be proved. A blasting dynamic model is established to characterize the effect of parameters of each damping hole, and the correctness of the model is verified by comparing with the field monitoring data. Furthermore, the influence law of damping hole parameters on damping rate is explored, and the relationship between damping rate and damping hole parameters is put forward, and the blasting vibration control benefit of damping hole in close tunnel blasting is demonstrated. The results show that:(1) 1~ 3 rows of damping holes were arranged respectively, and the average damping rate increases from 40.58% to 71.99%. (2) The distance between vibration reduction holes and explosion source of 0.75 m ~ 1.5 m is averaged, and the average damping rate decreases from 53.93 % to 40.21%. Changing the parameters of above has obvious influence on the damping absorbing benefit. (3) The relationship between parameters of damping hole and damping rate is shown. The significant degree of influence of damping hole parameters on blasting vibration is revealed; (4) The influence law of damping hole on blasting vibration of adjacent tunnel is shown. The vibration velocity is high and the attenuation is fast 5 m after the blasting face, and the damping hole has good vibration reduction benefit. The vibration reduction rate of each part of the central section can reach 26%-38% by a single row of damping holes.