爆炸荷载作用下砌体墙碎片分布分析

正确预判结构在不同爆炸事件中可能产生的碎片分布特性,对提高结构的抗爆安全性和减轻爆炸灾害具有重要意义。基于连续损伤力学和裂缝微观发展理论,进行了砌体墙在爆炸荷载作用下产生的碎片尺寸分布分析,得到了概率密度函数;根据空气动力学原理,计算了碎片形成后的抛射轨迹和抛射距离,并进行概率统计分析,得到不同爆炸工况下碎片的概率密度函数。数值分析结果表明:碎片尺寸分布符合广义极限分布规律;碎片抛射距离的分布因比例距离不同而有所不同;比例距离较小时,抛射距离的分布符合广义极限分布;比例距离较大时,抛射距离分布符合指数分布;碎片尺寸的均值和方差均与比例距离呈线性关系;抛射距离的均值和方差与比例距离之间的关系可用波尔兹曼方程表示。

Fragment distribution analysis of masonry wall under blast load

In order to improve the explosive security of structures and reduce the hazards caused by blast events,it is significantly important to predict the fragment distribution in different blast scenarios.In this paper,a numerical method based on theories of continuum damage mechanics and micro-crack development mechanics was employed to analyze the fragment size distribution of masonry wall under blast loading,by which the probability density functions of fragment size were given.Moreover,according to aerodynamic mechanics,the trajectory and launch distance of the ejected fragments were calculated,and the probability density functions of fragment launch distance were examined by statistical analysis for several blast scenarios.The numerical results reflect that fragment size distribution of masonry wall subjected to blast load basically follows the general extreme value distribution.However,the distribution of fragment launch distance depends on scaled distance,which approximately follows the general extreme value distribution as well when the scaled distance is comparatively smaller,whereas it appears to follow the exponential distribution when the scaled distance is larger.It is found that both the mean value and the variance of fragment size are linearly related to scaled distance,but those of fragment launch distance are related to scaled distance by the Boltzman equation.