Small-scale explosion experiments were conducted to assess the effect of the shape of a modeled underground magazine on the outside blast-wave propagation. The magazine model was divided into a chamber and a passageway; the internal diameter of the chamber (D0) was fixed at 38.8 mm, while that of the passageway (D1) was varied so that their ratio (D1/D0) ranged at 0.26 and 0.76. The results were compared with the experimental ones previously reported for D1/D0 = 0.51 and 1.00. The experiments provided the azimuthal distribution of the peak overpressure for this model, showing that a narrow passageway can greatly mitigate the peak overpressure outside the magazine under the tested conditions. The data were obtained to determine the isobar of the peak overpressure for an arbitrary shaped underground magazine. An empirical equation of this experimental isobar is proposed for a circumscribed circle; the properties of the center and radius of this circle were described as a linear function of the scaled radius of the isobar of the surface explosion and their gradients decreased when reducing D1/D0.
scale-model experiment, overpressure distribution, high explosive, magazine shape effect, hazardous materials management