爆炸载荷下拱坝脆性动力损伤有限元分析

Finite element analysis of brittle dynamic damage in arch dam under blast load

基于连续损伤力学理论,用三维各向异性脆性动力损伤模型分析了拱坝及其岩基在爆炸载荷作用下的动力损伤问题.把损伤应变能释放率的概念引入岩石类介质的脆性动力损伤演化模型,并应用于独立研制的三维各向异性脆性动力损伤有限元程序(3-DADDFEP),利用该程序对上述问题进行了有限元分析.研究表明,爆炸载荷作用附近以及其对应坝体背面的相应位置最易发生损伤破坏;爆炸载荷的峰值和持续时间对损伤的发展和扩散有重要的影响,当爆炸载荷产生的动应力远远高于材料的损伤发展门槛值时,材料的损伤将会急剧增加,这对结构的安全是极为不利的;由于爆炸载荷的作用时间比较短,损伤破坏的局部特征比较明显.

Three dimensional finite element analysis of anisotropic brittle dynamic damage mechanism problem for arch dam and rock foundation subject to blast load was carried out. The concept of damage strain energy release rate was taken into account to develop the dynamic damage evolution model employed in the developed three dimensional anisotropic dynamic damage finite element program. The process of dynamic response in the dam due to the blast load was numerically simulated. The results showed that the serious damage appeared at the position of the dam back near the load range where the dam surface is much easer to damage. The peak value and the duration time of the blast-impact load have important influence on dam- age growth and damage propagation. When the dynamic stress due to the impact load was higher than that of the threshold value of damage developing in the material, the damage in the material would grow sharply, that may be extremely adverse to the structure safety. Because the duration period of the blast load lasted for a very short period, the localization of the damage was not quite obvious.