带环向表面裂纹海洋管道的断裂计算与可靠性评估

针对带环向表面裂纹海洋石油管道断裂可靠性问题,利用权函数方法,给出了计算裂纹前沿应力强度因子的积分表达式,进而导出了能满足工程精度要求的应力强度因子的实用计算公式。采用极限分析方法建立了带裂纹海洋石油管道断裂可靠性评估模型,给出了断裂失效概率和可靠度的计算公式。典型算例数值计算结果表明:应力强度因子随裂纹深度和长度的增大而增大,这与《应力强度因子手册》(科学出版社)的结果一致;当弯矩不变,裂纹深度和长度、管道壁厚和半径,及轴力为随机变量时,带裂纹海洋管道的可靠度随轴力均值的增大而减小。

Fracture and reliability assessment on submarine pipelines with circumferential surface cracks

Using the weight function method,the fracture of a submarine pipeline with circumferential surface cracks is studied.A practical formula for evaluating the stress intensity factors is derived,which is important in ocean engineering.Based on the solutions of stress intensity factors and statistical models of uncertainties,a reliability assessment method for submarine pipelines with surface cracks is proposed and a computational formula for predicting the probability of fracture is given.Finally,a typical numerical example is presented to illustrate the proposed method.The results show that the calculated stress intensity factor value will augment as increases of the length and depth of the crack,and the conclusion is consistent with those from the existed references.Taking the length and depth of the cracks,the thickness and radius of the pipe,and the longitudinal stress as random variables,the reliability of the crack submarine pipe will be decreased as expanding of the mean of the longitudinal stress while the bending moment keeps constant.