向家坝水电站纵向围堰堰脚冲刷可靠性分析

Reliability analysis on the toe scouring of longitudinal cofferdam for Xiangjiaba Hydropower Station

在由能量方程及临界受力平衡方程得到块石起动流速公式的基础上,系统分析了影响围堰堰脚冲刷的主要因素,以及河道来流不确定性与块石起动不确定性之间的关系。运用可靠性理论,以河道来流流速超过块石抗冲流速的概率来刻画堰脚冲刷风险,提出了纵向围堰堰脚冲刷的可靠性模型,给出了冲刷风险率Monte-Carlo计算方法。通过对向家坝水电站物理模型试验结果的对比分析,说明理论计算模型和方法是有效的、可行的。

Based on the incipient velocity of rubble derived from the strength balance and energy equation of mobile sands the dominating factors affecting the toe scouring of longitudinal cofferdam are systematically discussed and the relation of uncertainties between the construction flood and incipient velocity of rubble is analyzed. Then the application of the dependability theory an erosion reliability model of rubble on the toe of cofferdam is erected in which the erosion risk is measured by the probability that current velocity of river way exceeds incipient velocity of rubble. And Monte Carlo method is put forward for computation. Comparing with the physical model test data of Xiangjiaba Hydropower Station it showed that the reliability model and computation method are reasonable and effective.