边坡系统可靠度区间估计方法

An interval estimation method of slope system reliability

提出了一种高效边坡系统可靠度区间估计方法.首先,介绍了边坡系统可靠度点估计方法,采用Copula理论构建了抗剪强度参数相关结构并在此基础上提出Copula空间的子集模拟方法.其次,采用Bootstrap方法模拟了土体抗剪强度参数的统计不确定性.最后,基于以上方法提出了边坡系统可靠度的区间估计方法,并以一个均质边坡算例进行了说明.结果表明:子集模拟方法能够在准确估计边坡系统可靠度的同时大幅提升计算效率;Bootstrap方法可以较好地模拟土体抗剪强度参数的统计不确定性;考虑到抗剪强度参数的统计不确定性,不应仅仅将边坡系统可靠度表征为单一可靠度指标,而是应表征为具有一定置信度水平的置信区间;随着样本数目的增多,边坡系统可靠度指标的置信区间会随之变窄;随着边坡失效安全系数阈值的增大,其系统可靠度指标的均值将会减小,同时其系统可靠度指标的置信区间也将会随之变窄.

This paper proposes an efficient interval estimation method for slope system reliability.Firstly,the point estimation method for slope system reliability is introduced,which Copula theory is used to build the correlation structure for shear strength parameters,what’s more,Copula-based subset simulation method is promoted.Secondly,the statistical uncertainty of shear strength parameters is simulated with Bootstrap method.Finally,an interval estimation method for slope system reliability is proposed based on the abovementioned methods,illustrated with a homogeneous slope example.The results show that the subset simulation method could tremendously promote the efficiency of slope system reliability evaluation with high accuracy.The statistical uncertainty of shear strength parameters could be well simulated with Bootstrap method.The reliability of slope system should be characterized with a confidence interval rather than a simple index while the statistical uncertainty is concerned.The reliability index interval of slope system will decrease along with the increase of sample sizes.The reliability index and its interval of slope system will decrease along with the reduce of the minimum factor of safety.