Attenuation effect of mixture of water gel and foam polystyrene on blast wave was studied. Two sizes of spherical PMMA container, of which diameter were 100 mm and 200 mm, respectively, were prepared. 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. The containers were filled with the mixture. Spherical pentolite (0.1 kg) was ignited at the center of the each container. Three pressure transducers were placed around the container and the blast pressure was measured. The scaled distance from the charge to the three transducers were 3, 4, and 5 mg·kg-1/3, respectively. The relation between the density of the surrounded materials and the attenuation effect on the blast wave was discussed. In regard of the peak pressure, 200 mm-diameter container was much effective. The attenuation effect was maximum at the density of 0.54 g·cm-3. The peak pressure in such a case decreased to 45-53 % of that in case without the surrounded materials. On the contrary, in regard of the positive impulse, the maximum attenuation effect of two sizes of the containers was comparable, although the most effective density was different. The impulses in such cases were about 70 % of that without the mixture. This result shows that not only the mass of the surrounded barrier materials but also the porosity of the surrounded materials plays an important role for attenuation of the blast waves.
爆薬を緩衝材で覆った状態で点火し，周囲における爆風圧力の時間履歴を計測することにより，緩衝材の爆発影響を低減する効果の評価を行った。爆薬には100 gの球形ペントライトを用いた。緩衝材には，ゲル化水と発泡スチロール微小球の混合物を用いた。両者の混合比を変えることにより，かさ密度を0.12 g·cm-3 から 1.0 g·cm-3の範囲で変化させ，爆発影響低減効果のかさ密度依存性を調べた。また，直径100 mm，200 mmの２種類の大きさの球形容器を用意し，爆風低減効果の緩衝材量依存性を調べた。換算距離3, 4, 5 m･kg-1/3の３点で爆風圧の計測を行った。ピーク圧力は，200 mm容器の時に低減効果が大きく，緩衝材の密度0.54 g·cm-3の時に低減効果が最大となった。この時のピーク圧力は，緩衝材がない場合に対して，45−53 %であった。一方，正相のインパルスに関しては，容器サイズによらず，最も低減効果が大きかった場合のインパルスは，緩衝材がない場合に対して70−80 %程度であった。ただし，容器サイズにより，低減効果が最大となる緩衝材密度は異なった。以上のように，爆風圧低減効果には，緩衝材量依存性があると共に，緩衝材密度依存性があり，ピーク圧力とインパルスでは挙動が異なることが明らかになった。
Blast wave, Attenuation, Water gel, Foam polystyrene