变化水位下温度荷载对大坝工作性态的影响

Impacts of temperature loads on working behavior of arch dam during changing water level

现有拱坝设计规范的温度荷载假定上游库水位固定在正常蓄水位,而实际上游库水位在运行中是不断变化的。研究表明,固定水位与变化水位条件下的温度荷载存在较大的差异。以西南某拱坝为例,对同一高程处温度年变化采用傅立叶级数展开,开展变化水位下拱坝温度荷载的研究,对比分析了固定水位和变化水位下两种温度荷载及温度荷载作用下应力与变形的差异。结果表明:变化水位下温度荷载同固定水位下温度荷载的差值随深度的增加基本呈先增大后减小的趋势。在其他荷载一定时,固定水位温度荷载作用下的变形值稍大于变化水位温度荷载作用下的变形值,最大应力均要大于变化水位温度荷载作用下的最大应力。

The present design specifications for the arch dam assume that the water level in the reservoir is normal at the normal water level for computing temperature loads, however, the water level varies continuously in fact. The research results show that there exists a large difference of the temperature loads between the normal water level and changing water level. This paper takes an arch dam located at the southeast of China as an example. According to the temperature changes at the same elevation, the annual temperature change is expanded by Fourier series, the temperature loads at different water levels are analyzed, and some comparisons are made for the stresses and deformations under temperature loads at the normal water level and the changing water level. The analysis results show when the depth of water increases, the difference values of the temperature loads at the normal water level and the changing water level increase first and then decrease. While other loads keep constant, the stresses and deformations under the temperature loads at the normal water level are greater than those at the changing water level.