基于贝叶斯理论的大坝体系可靠度计算方法

Calculation method for system reliability of dam based on Bayes theory

提出了大坝体系可靠度的改进计算方法.首先,通过响应面法拟合极限状态函数,进而通过JC法求出大坝单元的失效概率.然后,通过设定失效模式,以复合极限状态函数为准则,搜索出相应的失效路径;基于贝叶斯公式和Cauchy-Schwarz不等式,通过推导得出大坝以某种失效模式失效时的失效概率的上限,从而得出大坝整个体系的可靠度.最后,结合规范,施加地震荷载、静水压力和动水压力进行了实例验证,并对各种荷载进行了敏感性分析.结果表明,与常规求解大坝体系可靠度方法相比,其优点为考虑了多条失效路径,使用的为其失效概率的上限,计算偏于保守.

An improved calculation method for system reliability of dam is proposed.Firstly,through fitting limit state function by response surface method,the failure probability of dam units was obtained by JC method.Then,the failure paths were searched by setting failure mode according to composite limit state function,and based on Bayes formula and Cauchy-Schwarz inequality,the upper limit of failure probability for failure mode and system reliability of dam were deduced.Finally,according to the criterion,seismic load,hydrostatic pressure and hydrodynamic pressure were applied to the gravity dam model to verify the example and sensitivities of these loads were analyzed.Compared with other conventional algorithms,this method has some strong points：more failure paths are considered and the upper limit of failure probability is used for greater security.