The Development of the Generating Device for Shock Wave

In order to achieve a non-contact and a non-destructive inspection system for the concrete walls of tunnel in Shinkansen railway, a new testing device is forced to be developed. We proposed a new device which consisting of the Laser Doppler Vibrometer system, and generating shock waves. This is the reason why we developed the gun which was the generating shock wave and experimented to investigate the behavior of shock wave propagation by using it. We investigated shock waves in three cases of an explosive without casing, with a cylinder, and with a gun, respectively. As a result, the static overpressure and the impulse obtained in the case of using a gun were the highest among three cases. We obtained the empirical equations which represent the relation between the static overpressure and the scaled distance (m/kg^1/3) where in ratio of the distance and one third power of the weight of explosive. For the impulse, the empirical equations are also obtained. We obtained the static overpressure at various distances and azimuth angles from the passageway exit of the gun. The static overpressure and impulse were almost same in the range from θ = 0° (the axis of the gun) to θ = 15°. There was no difference between the static direct overpressure and that one reflected from a concrete board in the axis direction of the gun. We also investigated the mean velocity of propagation and the distribution of the static overpressure. We investigated to ignite nitromethane by using the triggering device using the high electric current.