A numerical simulation study explores the effects of initial defects on the collapse strength of pipelines under external pressure, with a focus on the coupling effect of multiple initial defects. The collapse strength of pipelines with only one initial defect is studied and the effects of the length and amplitude of the defect are determined. Then, pipelines with multiple initial defects are analysed and the effect of the distance between two initial defects is investigated. The critical distance between defects is determined in order to determine whether there exists any coupling effects between defects. In the case of coupling, the equivalent length of the two initial imperfections is derived. Based on the calculation results a simplified equation is proposed to describe the ultimate collapse strength of pipes with localised initial defects.

数值模拟研究探讨了初始缺陷对外压下管道坍塌强度的影响，重点研究了多个初始缺陷的耦合效应。研究了只有一个初始缺陷的管道的坍塌强度，并确定了缺陷长度和幅度的影响。然后，分析了具有多个初始缺陷的管道，并研究了两个初始缺陷之间的距离的影响。确定缺陷之间的临界距离以确定缺陷之间是否存在任何耦合效应。在耦合的情况下，推导出两个初始缺陷的等效长度。根据计算结果，提出了一个简化方程来描述具有局部初始缺陷的管道的极限坍塌强度。