多失效模式与变量相关的管道失效概率预测

Prediction of pipeline failure probability with multiplefailure modes and variable correlation

针对腐蚀管道多失效模式相互竞争、变量非独立的特点以及小失效概率预测效率低的问题,提出一种基于子集模拟法(SS)的腐蚀管道时变失效概率预测方法。基于泄漏与爆裂失效的极限状态函数,考虑泄漏与爆裂失效的竞争关系,构建管道竞争失效概率预测模型;使用Nataf转换方法描述模拟样本中缺陷深度与长度的相关性,提出考虑失效模式竞争性、变量相关性的腐蚀管道失效概率求解方法,并采用蒙特卡罗模拟(MCS)验证该方法;应用上述方法,探究缺陷深度和长度的弱相关性(相关系数0~0.3)对管道服役15年内失效概率的影响。结果表明:失效概率大于10-6时,使用该方法的计算结果与MCS计算结果基本相同,计算效率高于MCS,且可预测概率水平为10-12的极小概率事件;管道服役15年内,缺陷变量相关系数越大,管道爆裂失效概率越大,越早到达爆裂失效概率阈值年限;而随着相关系数的增大,泄漏失效概率越小,越晚达到泄漏失效概率阈值年限;在预测后期,相关系数增大对2种失效概率的影响均减弱。

Aiming at the problem of competing multiple failure modes and dependent variables of corroded pipelines,and low efficiency of predicting the probability of small failures,a time-varying failure probability prediction method for corrosive pipelines based on SS method is proposed.Based on the limit state function of leakage and burst failure,considering the competition between leakage and burst failure,a prediction model for the pipeline competitive failure probability was constructed.In order to solve the above model,the Nataf transformation method was used to describe the correlation between the depth and length of the defects in the simulated samples,and a method to solve the failure probability of corroded pipelines was proposed by considering the competitiveness of failure modes and the correlation of variables.Monte Carlo Simulation(MCS)was used to verify the above method.Finally,the above method was applied to investigate the effect of the weak correlation(correlation coefficient 0-0.3)between defect depth and length on the probability of failure within 15 years of pipeline service.The results show that when the failure probability is greater than 10-6,the calculation results of this method are basically consistent with those of MCS,and the calculation efficiency is higher than that of MCS,and the minimal probability events with the probability level of 10-12 can be predicted.Within 15 years of pipeline service,the greater the correlation coefficient of defect variables is,the greater the probability of pipeline burst failure is,and the earlier it reaches the threshold year of burst failure probability.As the correlation coefficient increases,the smaller the probability of leakage failure is,and the later it reaches the threshold year of leakage failure probability.At the later stage of the prediction,the effect of the correlation coefficient increase on the probability of the two kinds of failures is weakened.