近距离爆炸比例爆距的界定标准及荷载模型

如何准确界定“近距离爆炸（close-in explosion）”一直是防护工程研究领域的热点。本文中基于已被充分验证的精细化有限元模型，研究了TNT球形装药自由场爆炸冲击波传播与爆轰产物高速膨胀共同作用的特点和规律，发现在比例爆距小于0.80 m/kg1/3的范围内，爆轰产物对刚性壁面的爆炸荷载影响显著，提出球形装药近距离爆炸的比例爆距界定标准为0.30～0.80 m/kg1/3。研究发现，在近距离爆炸下，爆炸波在入射角为0°～5°范围内的刚性壁面反射荷载峰值会出现急剧下降的现象，这是由爆轰产物喷射的不均匀性和随机性导致的；近距离爆炸下，刚性壁面反射超压出现了两个峰值的现象，这是由冲击波和爆轰产物分别与刚性壁面相互作用导致的。提出了近距离爆炸情况下两个荷载峰值的计算公式，以及适合工程结构响应计算的简化荷载模型；揭示了近距离爆炸下刚性壁面反射超压的分布规律。

Definition of scaled distance of close-in explosion and blast load calculation model

How to accurately define “close-in explosion” has always been a hotspot in the field of protection engineering research. In this paper, based on the fully validated 2D axisymmetric fine finite element model, the characteristics and laws of the propagation of air shock waves and high-speed expansion of detonation products generated by TNT spherical charge were studied. It is found that there is a significant influence of the detonation products on the blast load on rigid wall when the range of the scaled distance less than 0.8 m/kg1/3. It is recommended to use the scaled distance range from 0.30 m/kg1/3 to 0.80 m/kg1/3 as the definition criterion of close-in explosion for spherical TNT charge explosion. It was found that: due to the inhomogeneity and randomness of the detonation product rapid expansion, the peak value of the rigid-wall reflected overpressure experienced a sharp drop within a range of incident angle of 0°～5° in the case of close-in explosion defined in the paper. In addition, there were two peaks on the reflected overpressure curve in close-in explosion cases, and the first peak overpressure was caused by the interaction between the shock wave and rigid wall while the second peak overpressure was generated by the interaction between the detonation products and rigid wall. Based on curve fitting, the formulas for calculating the two peak values were proposed, respectively, and a simplified load model suitable for calculation of engineering structure response was put forward; The distribution law of the reflected overpressure on the rigid wall under close-in explosion was revealed.