考虑非正态变量相关性的重力坝抗滑稳定可靠度研究

为了研究相关非正态变量对重力坝抗滑稳定可靠指标的影响，采用Jc法、映射变换法和实用分析法计算了具有独立非正态变量时某重力坝抗滑稳定的可靠指标，以及用二阶矩矩阵法计算了非正态变量抗剪断摩擦系数f和黏聚力c字在相关性时重力坝抗滑稳定的可靠指标。通过计算分析表明：理论上Jc法、映射变换法、实用分析法三种方法对独立非正态变量的正态化处理方式有所不同，但对于文中实例计算结果基本一致；当变量间不考虑相关性时二阶矩矩阵法蜕化为Jc法；重力坝抗滑稳定的可靠指标随着f和c之间负相关系数的减小而增大,f和c’采用正态分布概率模型计算的重力坝抗滑稳定的可靠指标比f和c采用对数正态分布概率模型计算的重力坝抗滑稳定的可靠指标小。

Reliability analysis of stability against sliding of gravity dam foundation based on correlatednon-normal random variablest

In order to study the influence of correlated non-normal random variables to the reliability index of stability against sliding of gravity dam foundation, the reliability index of stability against sliding of gravity dam foundation for independent non-normal random variables is calculated using JC method, Mapping Transformation method and Practical Analysis method in the paper. At the same time, the reliability index of stability against sliding of gravity dam foundation is also calculated when the correlation between the non-normal variables shear friction coefficient and cohesion is considered. The conclusions are obtained as： （1） although in the JC method, Mapping Transformation method and Practical Analysis method, different theoretical methods are used to transfer the non-normal variables to normal variables, the resultant reliability indexes of engineering example are almost the same; （2） method of second moment matrix degenerates into JC method when the correlation between variables are not considered; and （3） the reliability index of stability against sliding of gravity dam foundation increases along with the decreasing of negative correlation factor between f and c, and the reliability index obtained on the basis of f and c by normal distribution probability model is smaller than by lognormal distribution probability model.