石灰岩中球形装药封闭化爆试验的自由场应力和地运动

FREE-FIELD STRESS AND GROUND MOTION OF UNDERGROUND CONFINED CHEMICAL EXPLOSIONS WITH SPHERICAL CHARGE IN LIMESTONE

对石灰岩中50,100,800,1000和2000kg TNT的系列球形装药封闭爆炸试验的350km/kt1/3比例爆距内的自由场应力波和30km/kt1/3比例爆距内的地运动测量数据,按爆炸相似律进行归一化分析处理,拟合得到自由场应力、地表粒子速度、地表比位移及地表比加速度等特征参量峰值随比例爆心距的衰减规律,并与硬岩(花岗岩、砂岩、石灰岩)中的核爆相应结果进行对比。结果表明,化爆试验的地表比加速度峰值远小于核爆的,其他特征参量的峰值衰减规律与核爆的大体一致。讨论与自由场应力波、地表运动参数测量及数据分析相关的若干问题,指出:只有通过现场试验积累足够的数据资料,从统计学的角度来研究,才能比较客观地了解岩体中爆炸的自由场和地运动变化规律,而化爆能在一定程度上模拟核爆的力学效应。在自由场应力波测量中,化爆模拟试验需要更高频响的测试系统。在地表运动测量中,由于波传播路径上的岩体对高频波的吸收很强,在一定比例爆距外,化爆与核爆的地运动信号频率并无太大的差别,波传播路径上的岩体性质对加速度参量的影响最大,这是化爆比例加速度峰值远小于核爆的主要原因。

According to the cube root scaling law, the test data of flee-field stress（scale distance in 350 m/kt1/3）and ground motion（scale distance in 30 km/kt1/3） of a series of confined chemical explosion with spherical charges of 50, 100, 800, 1 000, 2 000 kgTNT in limestone have been analyzed, the attenuation of the free-field peak stress and the ground surface peak particle velocity, peak scaled particle displacement and peak scaled particle acceleration with scale distance are fitted, all the characteristic parameters are compared with that of nuclear explosion in hard rocks（granite, sandstone, limestone）. The results show that, the ground surface peak scaled particle acceleration is far low in chemical explosions, and the others are principally in agreement with that of underground nuclear explosions. Some problems about in-situ measurements and data analysis are discussed, that mechanics effects of underground nuclear explosion could be to a certain extent simulated with underground chemical explosion is emphasized, and that a large number of on site data should be fitted statistically and it would be helpful in understanding the objective laws is also indicated. The instruments with higher frequency response must be provided in measuring free-field stress on underground chemical explosion. The higher frequency wave is attenuated quickly while propagating in rock mass, there are not distinct differences between ground motion frequencies of chemical explosion and nuclear explosion beyond a certain scale distance, acceleration is more sensitive to rock property on the travel path especially, which is the reason why the measured ground surface peak scaled particle acceleration is far low in chemical explosions.