基于贝叶斯理论的土石坝结构风险分析

Bayesian theory for quantifying structural risk of earth-rock dam

提出了基于贝叶斯理论的土石坝结构风险分析方法。首先,介绍了土石坝结构风险计算模型的原理。其次,将土石料渗透系数和抗剪强度参数作为结构风险计算模型的输入参数,其概率分布模型的识别和建立将直接影响风险分析的结果,故基于贝叶斯理论的模型识别法和马尔科夫蒙特卡洛模拟法来描述输入参数的概率分布。最后,以广西境内小峰水库土石坝的现场试验数据为例,计算了小峰水库主坝的结构风险。结果表明,结构风险计算模型充分考虑了渗透破坏失事和坝坡失稳失事,表征出土石坝隐藏的结构风险,实现了土石坝结构失事的量化;该方法能够充分利用有限的现场试验数据,表征出随机变量的模型不确定性和统计不确定性,从而更精确地计算出土石坝结构风险率。

A method for structural risk analysis of earth-rock dams based on Bayesian theory is proposed. First,the principles of the structural risk calculation model for earth-rock dams are introduced. Secondly, the permeability coefficient and shear strength parameters are used as the input parameters of the structural risk calculation model. The identification and establishment of the probability distribution model will directly affect the results of the risk analysis, so the model identification method based on Bayesian theory and Markov-Monte Carlo simulation method are used to describe the probability distributions of input parameters. Finally, taking the field test data of the Xiaofeng Reservoir earth-rock dam in Guangxi as an example, the structural risk of the main dam of Xiaofeng Reservoir is calculated. The results show that the structural risk calculation model fully considers penetration damage wreck and dam slope instability crash, characterizes the hidden structural risks of earth-rock dams, and realizes the quantification of earth-rock dam structural failures. The model identification method based on Bayesian theory and Markov-Monte Carlo simulation method can make full use of the limited field test data to characterize the model uncertainty and statistical uncertainty of random variables, so as to calculate more accurately calculating the structural risk rate of earth-rock dams.