乐滩水电站运行期大坝变形特性分析

以原型监测为基础,将实测值分析与理论推导相结合,对乐滩水电站运行期大坝变形的时空分布规律进行分析和评价。位移分析表明：坝基变形量及测值变幅普遍小于坝顶,由于分析时段内库水位变化较小,温度是影响坝体变形的控制因素;坝顶沉降量冬季大、夏季小,沿横河向呈不规则敞口＂U＂形分布,河谷坝段沉降普遍大于岸坡坝段;坝顶水平位移夏季向上游变化,冬季向下游变化,沿横河向呈不规则敞口＂W＂形分布,这与不同坝段的结构有关。挠度分析表明：坝体水平变形量随观测高程的降低呈递减规律,坝顶衰减速率快,至坝基变形趋于稳定。综合分析认为,坝体变形的时间演化规律和空间分布规律正常,大坝目前处于安全状态。

Dam Deformation Characteristic Analysis of Letan Hydropower Station in Operation Period

Based on the prototype monitoring, the temporal and spatial distribution rules of the dam deformation of Letan Hydropower Station in operation period are analyzed and evaluated by combining the measured values with the theoretical derivation. The displacement analysis show that the deformation values and change magnitudes on top of the dam are much higher than that on the bottom, and the temperature is the key factor to impact the dam deformation in the analysis period. The settlements on top of the dam in winter are higher than that in summer. The settlements along the dam axis appear irregular U- style distribution, settlements of dam blocks in the center are bigger than that of dam blocks on both sides. The horizontal displacements on top of the dam move to the upstream in summer, and move to the downstream in winter. The horizontal displacements along the dam axis appear irregular W-style distribution, which is related to the structures of different dam blocks. According to the deflection analysis, the horizontal displacements of the dam decrease with the decrease of the elevation, the decay rate on the top is much higher than that on the bottom and the deformation of the base is very small and stable. In conclusion, the temporal and spatial distribution rules of the dam deformation are normal, and the dam is in safety.