钙质砂介质中爆炸波传播规律的试验研究

Experimental study on blast wave propagation in calcareous sand

开展了一系列钙质砂和石英砂的地面爆炸试验,主要对比分析了两种砂土介质中爆炸波的传播规律,包括峰值压力、弹塑性波速及升压时间、爆坑尺寸等。试验结果表明,爆炸波在钙质砂中的传播与在石英砂中存在较大差异:地面爆炸作用下钙质砂爆坑较石英砂爆坑的直径和深度更小,且成坑形状为两阶同心圆;钙质砂中弹性波速为236~300 m/s,石英砂中弹性波速为218~337 m/s,弹性波速和塑性波速均随炸药质量增加而增大;爆炸波在钙质砂中的升压时间随比例距离的增加而增加,而在石英砂中升压时间随比例距离变化不明显,且较钙质砂中升压更迅速;在地面爆炸作用下,低含水率钙质砂的衰减系数为2.86,石英砂为2.79。

Calcareous sand is widely distributed in coastal areas,and its engineering and mechanical properties are significantly different from terrestrial sands.To study the blast wave propagation in calcareous sand,a series of explosion tests with various charge weights on the ground surface were carried out in calcareous sand and silica sand.Pressure time-history curves at positions directly below the explosion center were measured.The propagation laws of two kinds of sands were investigated,including peak pressure,wave velocities of elastic and plastic waves,the rise time of pressure and size of cater.The results show that the blast wave propagation in calcareous sand differs from that in silica sand.Tests under 0.2 kg and 0.8 kg charge weight were conducted twice.And the results show that the explosion experiment is repeatable.Cater produced by the surface explosion in calcareous sand has a smaller size than in silica sand,and the shape of the cater is two-tier concentric circles,one of which is small in diameter and large in depth,and the other is large in diameter and small in depth.The elastic velocity in calcareous sand is 236 m/s to 300 m/s,and that in silica sand is 218 m/s to 337 m/s,while the elastic wave and plastic wave velocity increase with the increase of the explosive charge.The rise time of the blast wave pressure in calcareous sand increases with the increase of scaled distance.In silica sand,rise time does not change with the scaled distance and is much smaller than that in calcareous sand.The measured peak pressures are fitted by using a power function of scaled distance.The attenuation laws of peak pressure in calcareous sand and silica sand are derived.The attenuation coefficient of calcareous sand with low moisture content is 2.86,and 2.79 for silica sand.