基于最大熵原理的施工导流随机模糊风险分析

摘要

Flood overtopping failure of the no-overtopped rockfill cofferdam,which has bad influence on the safety of the water resources and hydropower project and downstream,is characterized by randomness and fuzziness based on fuzzy probabilistic theory.A mathematical model for random fuzzy risk analysis of construction diversion system was established.Observed flood sequence was applied to determine annual maximum water level sequence before cofferdam.The maximum entropy principle and variational method were introduced to deduce the probability distribution of maximum upstream water level.Finally,the method was applied in a navigation and hydropower Junction project.The result showed that the model is effective,the maximum entropy distribution fits well with water level sample data,not only the analytic expression of water-retaining risk can be given,but also the rational evaluation of flood overtopping failure risk can be acquired,providing more valuable information for the decision-making of construction diversion standard and safety evaluation of diversion system.%土石不过水围堰漫顶失事具有随机性和模糊性,严重影响水电工程及下游的安全。基于模糊事件概率理论,构建了施工导流系统随机模糊风险分析数学模型。探讨利用实测洪水序列推求堰前年最高水位序列的计算方法。然后,引入最大熵原理和变分法来推导堰前最高水位的概率分布。最后,以某航电枢纽工程为例,结果表明,所建模型是有效的,最大熵分布与水位样本拟合良好,不仅能够得到围堰挡水风险的解析表达,而且合理地评估了围堰漫顶失事风险,为施工导流标准的制定和导流系统的安全评估提供了更多有价值的信息。