超高速弹撞击岩石的地冲击效应等效计算

An equivalent calculation method of ground shock effects of hypervelocity projectile striking on rock

本文主要研究岩石中超高速撞击与浅埋爆炸的等效转换计算方法。基于超高速动能弹丸撞击岩石的地冲击效应与岩石中浅埋装药爆炸效应的相似性,将表面弹坑作为引起地冲击的震源,根据超高速撞击弹坑与浅埋爆炸弹坑辐射出的地冲击能量相等条件,建立超高速撞击与装药爆炸的地冲击效应的等效关系。通过理论推导,得到超高速撞击效应的等效装药量与无量纲撞击速度的关系,并给出能量换算系数与无量纲撞击速度的简化表达式。依据超高速弹体撞击花岗岩的试验结果,证明等效装药爆炸与超高速撞击的地冲击应力波形十分吻合,验证等效方法的有效性。计算分析表明当弹丸撞击速度足够大(Ma≥1.5)时,可以进行爆炸等效转换,撞击速度不断增大时,等效装药量不断增大,能量换算系数不断增大。根据本文提出的地冲击效应等效计算方法,得到5,10,15马赫撞击速度下不同弹丸质量与最小防护层厚度间的关系曲线。

The purpose of this paper is to investigate the equivalent ground shock effects of hypervelocity impact and shallow buried explosion in rock. Based on the similarity of craters resulted from hypervelocity impacts and shallow buried explosions,the crater can be regarded as the source of ground shock effects,and the equivalent relationship between hypervelocity impact and shallow buried explosion can be established assuming that ground shock energies of them are equal. The relationship between the equivalent charge and the dimensionless impact velocity was obtained,and a simplified expression of the energy conversion coefficient was given. Experimental results of hypervelocity impact on granite indicates that the ground shock waves of equivalent charge explosion and hypervelocity impact are highly similar,which verifies the validity of the equivalent method in the case of a large enough dimensionless impact velocity. When the dimensionless impact velocity increases,both the equivalent charge and the energy conversion coefficient increase. Based on the equivalent method,the relationship curves between the safe thickness of protective layer and the mass of projectile were obtained with the impact velocity of 5 Mach,10 Mach and 15 Mach respectively.