内压作用下含体积型缺陷弯管极限载荷研究

Research on ultimate load of elbow containing volumetric defects under effect of internal pressure

油气管道一旦发生泄漏失效容易引发爆炸等灾难性事故,而管路中的弯管段是容易发生失效的部分,弯管段承载能力的高低将影响整个管道系统的安全性。为了解决油气管线中弯管的失效问题,考虑几何和材料非线性,建立内压作用下含体积型缺陷弯管的有限元模型,并与爆破试验结果对比验证模型的有效性,确定管道的失效判定准则。研究表明影响弯管极限载荷的主要因素有缺陷的几何尺寸、相对位置以及弯曲半径。基于模拟计算,讨论各因素对含缺陷弯管极限载荷的影响规律,通过对计算结果进行非线性拟合,提出内压作用下含体积型缺陷弯管的极限内压预测公式。该公式将为含缺陷弯管的剩余强度评价和完整性评价提供一定依据。

Once the oil and gas pipeline has a leak failure,it is easy to cause the catastrophic accident such as explosion,and the elbow in the pipeline system is a part that is prone to occur the failure,so the bearing capacity of the elbow section will affect the safety of the whole pipeline system.In order to solve the failure problem of elbow in theoil and gas pipeline,a finite element model of elbow containing the volumetric defects under the effect of internal pressure was established considering the geometric nonlinearity and material nonlinearity.The validity of the model was verified through the comparison with the results of blasting tests,and the judgment criteria of pipeline failure were determined.The results showed that the main factors affecting theultimate load of elbow were the geometry size of defect,the relative position of defect and the bending radius of elbow.The influence of various factors on the ultimate load of elbow containing defects was discussed based on the simulation calculation,and the nonlinear fitting of the calculation results was carried out.The prediction formula of ultimate internal pressure for the elbow containing volumetric defects under the effect of internal pressure was proposed,which can provide a certain basis for the residual strength evaluation and integrity evaluation of the defective elbows.