考虑验证荷载对服役大坝的可靠性分析

Reliability Analysis of a Dam in Service Considering Proof Load

受自然环境与使用环境的双重作用,大坝在服役过程中承受了各种荷载(验证荷载)的考验,不可避免会存在不同程度的损伤和缺陷。验证荷载对已投入使用大坝的可靠度的影响不可忽视,讨论验证荷载如何对服役大坝的可靠指标产生影响具有重大的意义。分析服从不同先验分布概率的抗力,在确定性验证荷载下,其后验分布的数字特征变化规律;利用条件概率方法,建立以验证荷载为条件的条件概率法可靠度计算公式,并考虑结构的抗力随时间衰减因素、验证荷载前后结构功能函数相关系数的大小、验证荷载的不同取值等方面对一实例大坝进行了可靠度分析。通过计算分析发现,服役大坝考虑验证荷载作用时的可靠指标比不考虑验证荷载时的值大,且可靠指标的增长幅度与验证荷载作用前后功能函数的相关系数大小有关。

Under the long-term action of natural environment and service environment,the dam has been tested by various loads(proof loads)in the service process,and inevitably there will be various damages and defects to different degrees.The influence of the proof load on the reliability of a dam in service can not be ignored.It is of great significance to discuss how the proof load affects the reliability index of a dam in service.In this paper,the numerical characteristics of the posteriori distribution of resistance under the deterministic proof load with different prior distribution probabilities were analyzed,and the reliability formula of the conditional probability method based on the proof load was established by using the method of conditional probability.The reliability of a dam was analyzed by taking into account the factors of structural resistance attenuation with time,the size of correlation coefficient of structural function before and after proof load,and the different values of proof load.It is found that the reliability index of a dam structure in service with the proof load is larger than that without the proof load and the increasing range of reliability index is related to the correlation coefficient of function relation before and after the proof of load.