基于FITNET FFS模型的腐蚀管道失效概率敏感性分析

为了获取影响腐蚀管道失效概率的关键因素及敏感性规律，基于FITNET FFS模型，采用可靠性理论对国内某腐蚀管道的失效概率进行计算和分析。通过全寿命方法计算了腐蚀增长速率，从而得到了与时间相关的腐蚀管道损伤概率模型，并采用蒙特卡罗模拟算法进行求解，得出了不同年限下腐蚀管道的失效概率；采用变异系数法对各影响因素进行参数敏感性分析。研究结果表明:管道直径、壁厚及径向腐蚀速率的分散性对管道失效概率具有双向扰动作用，其机理在于随机变量的分散性和腐蚀速率同时影响失效概率的波动，开始阶段随机变量分散性起主导作用，两者在管道失效概率达到50%会趋于一个平衡状态，之后腐蚀速率起主要支配作用；另外，管材的抗拉强度对腐蚀管道失效概率的影响较屈服强度的影响更大，可靠性分析时采用只考虑屈服强度的强度模型将存在一定的局限性，建议同时考虑管材抗拉强度的影响。

Sensitivity analysis on failure probability of corroded pipeline based on FITNET FFS model

In order to obtain the key factors and sensitivity laws that affect the failure probability of corroded pipeline, the failure probability of a domestic corroded pipeline was calculated and analyzed by using the reliability theory based on the FITNET FFS model. The growth rate of corrosion was calculated by means of the full life method, then the model on the damage probability of corroded pipeline with time related was obtained and solved by using the Monte Carlo simulation algorithm. The failure probability of corrosion pipeline under different years was obtained, and the parameter sensitivity of each influencing factor was analyzed by using the variation coefficient method. The results showed that the dispersibility of pipeline diameter, wall thickness and radial corrosion rate had the bidirectional disturbance effect on the failure probability of pipeline, and the essential mechanism of this phenomenon was revealed. The dispersibility of random variables and the corrosion rate influenced the fluctuation of failure probability at the same time, and in the initial stage, the dispersibility of random variables played a leading role, then they tended to an equilibrium state when the failure probability of pipeline reached 50%, while the corrosion rate played a dominant role after that. In addition, the influence of the tensile strength of pipeline material on the failure probability of corroded pipeline was greater than that of the yield strength, so adopting the strength model which only considered the yield strength in the reliability analysis had some limitations. It was suggested that the influence of the tensile strength of pipeline material should be considered at the same time.