管道环焊缝是油气输送管道的最薄弱环节，中国的管道敷设环境复杂，管道在附加外载和工作内压的共同作用下将导致环焊缝区域产生应力集中，极易导致管道失效。目前行业内预测管道环焊缝极限载荷的主要手段是标准反演法，该方法预测的结果相对保守，且仅适用于常规工况。为了更准确地预测管道环焊缝的极限载荷，对X80管道环焊缝进行了详细的材料力学试验和基于有限元反向标定法的GTN（Gurson-Tvergaard-Needleman）损伤参数的标定，在此基础上采用GTN损伤模型和子模型技术模拟了含裂纹缺陷的全尺寸管道环焊缝的损伤失效过程，得到了管道环焊缝在复杂载荷作用下的极限载荷。最后对仿真过程进行了试验验证，仿真预测的极限内压误差为3.1%，裂纹断裂时远端应变值的最大和最小预测误差分别为3.15%和1.10%。对比结果表明，采用的全尺寸管道环焊缝极限载荷预测方法可以准确地预测环焊缝在复杂载荷状态下的极限载荷，能够应用于管道环焊缝的安全评价过程。

Pipeline girth welds are recognized as the weakest link in oil and gas transmission pipelines. Given the complex pipeline laying environment in China, the combined effects of additional external loads and internal working pressures can lead to stress concentrations in the girth weld region, significantly increasing the risk of pipeline failure. Currently, the standard inversion method is used as the primary tool within the industry to predict the ultimate load of pipeline girth welds. However, relatively conservative predictions are yielded by this method, and it is only applicable to conventional operating conditions. To achieve a more accurate prediction of the ultimate load of pipeline girth welds, detailed material mechanics tests were conducted on X80 pipeline girth welds, and the Gurson-Tvergaard-Needleman(GTN) damage parameters were calibrated using the finite element inverse calibration method. Based on these parameters, the GTN damage model and sub-modeling technique were employed to simulate the damage and failure process of full-scale pipeline girth welds containing crack defects. The ultimate load of the pipeline girth welds under complex loading conditions was yielded by this simulation. Finally, the simulation process was experimentally validated, revealing a 3.1% error in the predicted ultimate internal pressure and maximum and minimum prediction errors of 3.15% and 1.10%, respectively, for the far-field strain values at the time of crack fracture. The comparative results demonstrate that the proposed method for predicting the ultimate load of full-scale pipeline girth welds can accurately predict the ultimate load under complex loading conditions, making it suitable for the safety assessment of pipeline girth welds.