冰区老龄平台整体时变可靠性分析与更新  

Analyzing and updating on the global time-dependent reliability for ageing platforms in ice zones

作　　者：陈团海[1] 陈国明[1] 林红[1] 

机构地区：[1]中国石油大学海洋油气装备与安全技术研究中心,山东东营257061

出　　处：《石油学报》2011年第3期518-523,共6页Acta Petrolei Sinica

基　　金：国家自然科学基金项目(No.50679083);中央高校基本科研业务费专项资金项目(09CX05008A)联合资助

摘　　要：建立了冰区老龄平台整体时变可靠性分析模型,并基于Bayes理论研究平台时变可靠性更新方法。根据现场实测冰力时程曲线,将冰载过程简化为具有随机强度和时间间隔的脉冲序列,利用泊松点过程描述冰载发生次数;采用平台极限状态时的基底剪力作为平台整体抗力指标,运用Weibull函数腐蚀模型预测平台抗力衰减;基于条件概率与载荷—强度干涉理论,建立冰区老龄平台整体时变可靠性微分方程,导出时变可靠性与失效率函数分析模型;给出基于Bayes理论对平台抗力衰减影响因子进行修正的方法,通过修正抗力衰减模型对老龄平台可靠性进行更新。分析渤海一冰区平台的时变可靠性,并利用检测数据进行可靠性更新。研究结果表明,随着服役时间的增加,平台可靠性迅速下降,失效率在初期缓慢增大,达到一定服役期后迅速上升。抗力衰减模型对平台可靠性与失效率的评估均有较大影响。随着更新次数的增加,平台抗力衰减函数概率分散性减小,可靠性与失效率准确度提高。Since the number of ageing platforms increased rapidly and ageing effects would imperil the safety and service ability of structures,the present paper brought forward an analysis model for the global time-dependent reliability of ageing platforms in ice zones and investigated update ways of the time-variation reliability based on the Bayesian theory.The ice-load process was simplified to be a pulse sequence with random intensity and intervals and the occurrence number of ice loads was described by the Poisson point process according to probabilistic characteristics of load intervals.The base shear force in the ultimate limit state was taken as a whole resistant index for offshore platforms and a corrosion model with the Weibull function expression was employed to study the resistance degradation of platforms.Based on the conditional probability model and the load-strength interference theory,a probability differential equation of ageing platforms in ice zone was established and analysis models of the global time-dependent reliability and failure-rate function were developed.A method to modify influential factors of the resistance degradation based on the Bayesian approach was given and the reliability update of ageing platforms through the modified degradation model was investigated.Finally,the time-dependent reliability of an ageing platform in an ice zone of the Bohai Bay was taken as an example and evaluated.The results indicated that the global time-dependent reliability of the ageing platform decreased rapidly with service-time due to deterioration and load accumulations.The failure rate at initial stages increased slowly and then quickly as the service time reached at a certain stage,showing the feature of a bathtub-like curve at the two latter stages.Variations in both the reliability and failure-rate function were significantly influenced by the resistance degradation model.With the increase of update,the probability dispersion of resistance degradation functions became smaller and the results of reliabil

关 键 词：老龄平台 冰区 Bayes更新 随机冰载过程 抗力衰减 时变可靠性 失效率函数 

分 类 号：TE852[石油与天然气工程—油气储运工程]