In this article, we report small-scale explosion experiments for assessing the effect of the shape of an underground magazine model on blast-wave propagation outside the magazine. The underground magazine model was divided into chamber and passageway sections. The internal diameters of the chamber and passageway sections were 38.8 mm and 19.8 mm, respectively. The length ratio L1/L0 between the chamber (L0) and passageway (L1) lengths varied from 0.125 to 2.0 in the experiments. The data was compared with previously reported experimental data from a model-scale magazine with a uniform inner diameter of 38.8 mm. Explosion experiments with this model provided the azimuthal distributions of peak overpressure and positive impulse caused by blast waves exiting the magazine. The interaction between the blast wave and the junction of the chamber and the passageway caused the multiple blast waves and multiple overpressure peaks appearing in pressure-time histories. A narrow passageway greatly mitigated the peak overpressure outside the magazine, but the ratio of the chamber to the passageway length showed no effect in the present conditions. The multiple blast waves tended to increase the positive impulse if the magazine was relatively narrow. The shape of isobars of the peak overpressure was independent of the length of the passageway in the present study.
cale model experiment, azimuthal overpressure distribution, high-explosive magazine, hazardous materials management