Study of the blast wave ejected from the semi-sealed concrete structure

The explosion experiment was conducted in a semi-sealed concrete structure such as a magazine in order to investigate blast wave characteristics ejected from an exit of the structure. Composition C-4 was set in the center of the structure that has an opened surface on one side as the exit. Reflection pressure and impulse of the blast wave ejected from the exit were measured with piezo-electric pressure sensors. As a result of the experiment, it was found that distributions of the reflection pressure was such as "M-shaped function", and the impulse was such as "Inversed U-shaped function" using the center-line of the exit as a symmetry axis, respectively. Moreover, numerical simulations showed that multiplied shock wave was occurred by a shock wave induced from the explosion and a reflection wave from the ground surface. In addition, this shock was more enhanced by a reflection wave that occurred on the exit wall. This effect caused non-uniform distribution for the blast wave ejected from the exit of the structure.