Dependence of Blast Attenuation on Weight of Barrier Materials

Abstract

The attenuation effect of barrier materials, which covers an explosive completely, on blast waves was studied. The density of the barrier materials was examined to make the barrier materials light and low in volume. Water gel, small spheres of foam polystyrene, and mixtures of these two materials were used as the barrier materials, and the density of the mixture was varied from 0.12 g•cm-3 to 1.0 g•cm-3 by changing the mixed volume ratio. Natural silica sand was also tested for comparison. A spherical PMMA container was filled with the barrier materials and a spherical pentolite (100 g) was ignited at the center of container. The blast pressure around the container was measured. The mixture of the density of approximately 0.55 g•cm-3 maximized the attenuation of the blast wave for the same volume. The attenuation effect depends not only on the weight of the barrier materials but also on the porosity. A mixture of a density of approximately 0.13 g•cm-3 maximized the attenuation of the blast wave for the same weight. Using porous materials, relatively light barrier materials can attenuate the blast wave effectively, if the volume is not restricted. The attenuation effect of sand was greater than that of water gel and a mixture for the same volume.

Blast Wave Mitigation from the Straight Tube by Using Water Part II - Numerical Simulation

“…Figure 5 shows the distribution of peak overpressure outside the tube; the origin on the horizontal axis is located at the tube exit, for 130-J and 50-J explosions without water, and for 130-J explosion with water. Lines and symbols denote data of the present simulations and the previous experiments [7], respectively. The peak overpressure decreases as the shock wave moves away from the tube exit.…”

“…This paper models experiments in which explosives are detonated inside a straight tube. [7] Figure 1 shows the calculation target. The square tube is 330 mm long and 30 mm on each side.…”

“…Homae et al [4] conducted experiments involving an explosion inside a subsurface ammunition magazine model (an L-shaped tunnel). In that study, the shock wave propagated along the water, whose presence inside the horizontal chamber might have further mitigated the peak overpressure outside.…”

“…However, it was difficult to clarify the mechanism of mitigation of the blast wave by water because of the complexity of the explosion phenomenon inside the model subsurface magazine with a cylindrical L-shaped tunnel. To simplify the explosion phenomenon, Homae et al [7] conducted explosion experiments with a straight square tube and measured the pressure inside and outside it in order to understand when and how water affects the blast wave. Their study showed that water clearly reduced the peak overpressure at a distance of 80 mm from the ignition point.…”

Blast mitigation by water in a bag on a tunnel floor

“…The authors also carried out the experiments to evaluate the blast pressure. In a series of the experiments, the authors found that small amount of water on the floor of its storage chamber mitigated the blast pressure remarkably [5]. The authors have been studied the mitigation mechanism by experiments [6,7] and numerical simulation [8,9].…”