混凝土中爆炸应力波衰减规律的数值模拟研究

基于Kong-Fang混凝土材料模型和LS-DYNA的多物质ALE算法，开展混凝土中爆炸波衰减规律的数值模拟研究。首先，基于已有实验数据对材料模型参数和数值算法的可靠性进行了验证，在此基础上分析球形装药在混凝土自由场中爆炸波衰减规律，利用量纲分析和数值模拟拟合了球形装药在混凝土自由场中近区爆炸波峰值应力计算公式并明确其适用范围；然后，分析装药埋深对混凝土中装药正下方不同距离处爆炸波峰值应力分布的影响，建立了耦合系数与装药埋深和测点距离之间的定量关系。结果表明:Kong-Fang混凝土材料模型可实现对混凝土中爆炸波传播衰减规律的高精度数值模拟；定义混凝土中装药质量系数和耦合常数，可定量描述装药埋深和测点距离对峰值应力耦合系数的影响；建立的混凝土中近区爆炸波峰值应力计算公式可较准确地快速预测不同装药埋深、不同测点距离和不同混凝土强度时爆炸波峰值应力。研究结果可为混凝土结构抗爆设计和爆炸毁伤评估提供参考。

Numerical study on attenuation of stress wave in concrete subjected to explosion

Based on the Kong-Fang concrete material model and the multi-material arbitrary Lagrangian Eulerian (MMALE) algorithm available in LS-DYNA, the attenuation of stress wave in concrete subjected to explosion was numerically studied. On the basis of comparative analysis of different material models, numerical algorithms and selection of appropriate mesh size, the proposed numerical algorithm and material models along with the corresponding parameters were firstly validated by comparing the numerically simulated spherical charge detonated in a concrete target with the corresponding test data in terms of peak stress and stress-time history. Then the attenuation of stress wave subjected to spherical charge detonated in concrete was numerically investigated, in which the radial and circumferential stress-time histories at different scaled distances were analyzed in detail to reveal the mechanism of stress wave attenuation. The numerical results were fitted to develop an empirical formula for the peak stress of the free-field compression wave in concrete at the close zone with the aid of dimensional analysis. Besides, the applicability of the developed empirical formula was also discussed. The influence of charge buried depth on peak stress in concrete at different distances was also numerically studied to develop a quantitative relationship between charge buried depth, distance and the so-called coupling factor. Numerical results demonstrate that the Kong-Fang concrete material model can be used to simulate the attenuation of explosion stress wave in concrete with good accuracy. The influence of the charge buried depth and the distance from charge the center on the coupling factor of peak stress can be quantified by defining the mass coefficient and coupling constant. The empirical formula for peak stress of compression wave in concrete at the close zone is appropriate for varied charge buried depth, distance and concrete strength. The present numerical results are useful for blast-resistant design and can provide a reliable reference for estimating the damage degree of concrete caused by explosion.