饱和钙质砂爆炸响应动力特性试验研究

Experimental study of dynamic behavior of saturated calcareous sand due to explosion

钙质砂是一种特殊的海洋沉积物,开展钙质砂在爆炸作用下动力响应特性研究具有重要的理论意义和工程实用价值。通过室内小型爆炸试验,研究饱和钙质砂在爆炸作用下土压力、孔隙水压力和质点振动加速度等参数的变化规律。结果表明:饱和钙质砂中爆炸应力波随距离增大而衰减,但随爆心距增大衰减速度呈减小趋势;随试样相对密度增大爆炸应力波的衰减速度趋缓;爆炸引起的超孔隙水压力在10～30 ms内到达峰值,在前3 min内快速消散,消散幅度达90%以上;双发雷管微差起爆相对于单发起爆,最大单段起爆药量相同,但微差起爆由于爆炸应力波的叠加,使得钙质砂动力响应加剧。与相同试验条件下石英砂爆炸响应对比表明,相同测点处钙质砂动力响应弱于石英砂,应力波在钙质砂中衰减速度远比石英砂快,说明饱和钙质砂对爆炸应力波有着极强的吸收和衰减作用;爆炸近区钙质砂颗粒大量破碎,形成爆炸破碎和压缩区,形成这几个区域所耗损的爆炸冲击能量大约占总能量的25%左右。

Calcareous sand is a special marine geotechnical sediment,which has unexpected physico-mechanical property due to its composition and structure.Study of dynamic characteristics of saturated calcareous sand under explosion has important theoretical and practical significance.This paper aims at studying attenuation rules of earth pressure,pore pressure and vibration acceleration in different relative density calcareous sands due to explosive load through model experiment.Results show that explosive wave attenuates as the distance increases in saturated calcareous sand,and attenuation speed decreases as the distance increases.Explosive wave attenuates slower as relative density increases;excess pore pressure due to explosion reaches the peak value within 10 to 30 millisecond,and about 90 percents excess pore pressure dissipates in the previous 3 minutes;since delay explosion is used in this experiment,dynamic behavior of saturated calcareous sand is more intensive because of explosive wave overlap.Calcareous sand has strong absorption and attenuation effect for P-wave due to its particle breakage characteristics,and about 25% explosion energy loosed to form crush zone,compression zone and damage zone.