高拱坝超载破坏过程的第一主应力统计分析

Statistic analysis on the first principal stress of elements for a high arch dam during overloading

利用ANSYS软件对某高拱坝超载过程进行超载数值计算,得到拱坝的超载破坏过程。先对超载过程单元第一主应力进行统计分析;再计算每次超载时每个单元第一主应力大小的变化率,统计单元第一主应力变化率在超载过程中的变化规律;最后结合数值计算及地质力学模型试验成果分析单元主应力变化规律所对应的承载力状态。研究发现:当结构达到极限承载力时,其第一主应力相对频数分布有较为明显的集中现象;在结构超载初期,单元第一主应力变化率较大的单元,在单元中所占百分率比例较高,单元第一主应力增长较快;随着荷载的逐渐增大,单元第一主应力增长变缓。当结构达到极限承载力时,单元第一主应力变化率较小的单元在单元中百分率所占比例较高。单元第一主应力变化率越分散,表明结构仍有较大的超载能力;变化率越集中,表明结构越接近超载极限。利用此规律可以较准确地确定高拱坝的极限承载力。

The failure process of a high arch dam is obtained by finite element commercial code ANSYS. The statistic analysis of element first principal stress is carried out firstly during the overload process and then the first principal stress changing rating of each element is obtained. It is found that the first principal stress of element concentrates obviously during overloading process. The element first principal stress increasing rate is grows rapidly at the initial stage of overloading, the proportion of element with a larger increasing rate is much larger. With the overload grows, the element first principal stress increasing rate is getting smaller. When it reaches the ultimate load, the proportion of element with a smaller increasing rate is much larger. The more structure reaches its ultimate load, the more element first principal stress increasing rate concentrates.