库水位快速变动条件下心墙坝上游坝壳自由水面线变化规律研究

为了计算渗水压力对心墙坝上游坝坡稳定性的影响，须掌握库水位降落时上游坝壳中自由水面的变化规律。本文利用模型试验模拟了上游坝坡坡比、库水位不同降落速率、坝壳料不同渗透系数对自由水面位置变化的影响，并把模型试验结果与有限元计算结果、经验公式法计算结果相比较。从试验结果及有限元计算结果可知，库水位降落速度越快，自由水面线位置越高，最高点高度越大。坝壳坡度越陡，自由水面的位置越低。坝壳料渗透系数达2.45×10-1 cm/s时，有限元计算分析结果比模型试验得到的自由水面最高点稍高，经验公式法得到的计算结果最小。

Variation laws of seepage lines in upstream shell of core dams under rapid drawdown of reservoir level

The variation laws of seepage lines in upstream shell of core dams under change of reservoir water level are investigated to calculate the influence of seepage pressure on the stability of upstream dam slope. Model tests are conducted to determine the variation laws of seepage lines under a variety of ranges of slope ratio of upstream dam slope, velocity of water level drawdown and permeability coefficient of dam shell. Comparison among model tests, finite element method and empirical formula method is also presented. The results reveal that the faster the reservoir level declines, the higher the seepage lines and the highest point. The steeper the dam slope, the lower the position of seepage lines. When the permeability coefficient is up to 2.45?10^-1cm/s, the highest point of the seepage lines obtained from the finite element analysis is little higher than that of the model tests. The result obtained from the empirical method is the smallest one.