Research On Attenuation Law Of Shock Wave In Tunnel Blasting And Design Of Reducing Equipment

In this paper,theoretical derivation,field test and computer numerical simulation are combined to study the attenuation law of explosive explosion propagation in open area and underground confined area respectively,and the attenuation formula of shock wave generated by explosive explosion in open area with detonation center distance is revised.In the open area,the attenuation rate of the peak value of shock wave overpressure is about 75.61 kPa/m when the detonation center distance is 1-3 m,10.12 kPa/m when the detonation center distance is 3-8 m,and the attenuation rate tends to be flat when the detonation center distance is more than 8 m,which is less than 0.48 kPa/m.In the confined area,when the distance between the detonation centers is 2-4 m,the peak value of shock wave overpressure attenuates rapidly,and the attenuation rate is about 43.61 kPa/m,while the attenuation rate at 4-8 m decreases,and the attenuation rate is about 7.38 kPa/m.The fluctuation occurs at 8-12m,which should be caused by the reflection of the shock wave propagating in the restricted area.After 12 m,the peak attenuation of shock wave overpressure tends to be gentle.When the detonation distance is greater than 8 m,the peak attenuation rate of shock wave overpressure is about 1.41 kPa/m.The propagation velocity of shock wave produced by explosive explosion in open area decreases rapidly with the increase of detonation center distance.The propagation velocity of shock wave decreases to about 30%of the initial velocity at the detonation center distance of 12 m.The attenuation law of explosive shock wave with different spacing and quantity of explosive under different cross-sectional area is simulated by ANSYS/LS-Dyna.Empirical formulas for the peak value and proportional distance of explosive shock wave in confined area and the section area of tunnel are obtained.According to the actual situation of blasting construction of metro tunnels and the relevant situation of existing wave-resisting equipment,a wave-resisting equipment,anti-scour trolley,is designed for blasting construction of Metro tunnels.This is a kind of movable non-dynamic wave resistance equipment which can be adapted to the blasting construction site of Metro tunnel.The calculation proves that the equipment can effectively block the shock wave produced by tunnel blasting.