内衬GFRP防护复合管壁原缺陷坑处应力重分布规律分析

为了深入研究内衬GFRP防护复合管壁在其原管道内腐蚀缺陷坑处的应力重分布状态以及其修复的效果，利用弹塑性力学中的平衡微分方程，建立了管道内腐蚀缺陷处的数学模型，采用有限单元法建立了含单个腐蚀缺陷的管道模型，并通过改变腐蚀缺陷坑的深厚比，将修复前后腐蚀缺陷坑处的应力状态进行对比分析。分析结果表明，腐蚀缺陷坑的深厚比对管道的应力分布有着显著的影响，所以在进行管道安全评估时应注意腐蚀坑深度的影响；在腐蚀缺陷坑深厚比0.1到0.8的分次增加的过程中，管壁腐蚀缺陷处的周向应力，径向应力，Mises应力都有增大的趋势；修复前腐蚀缺陷坑处的周向应力和Mises应力相近，径向应力较前两者小，三者中周向应力最大；在修复前后，管道腐蚀缺陷处的控制应力一般是周向应力，管道的失效可依据周向应力进行判断；修复后的内衬GFRP防护复合管壁，原始腐蚀缺陷坑处发生了应力重分布，其周向应力与Mises应力均有减小，修复效果明显。

Analysis of Stress Redistribution Law at the Original Defect Pits of GFRP Protective Composite Pipe Wall with Inner Lining

In order to conduct in-depth research on the stress redistribution state of the lining GFRP protective composite pipe wall at the corrosion defect pit in its original pipeline and its repair effect. A mathematical model of corrosion defects in pipelines was established using the equilibrium differential equation within elastic-plastic mechanics. A pipeline model containing a single corrosion defect was established using the finite element method, and the stress state at the corrosion defect pit before and after repair was compared and analyzed by changing the depth ratio of the corrosion defect pit. The analysis results indicate that the depth ratio of corrosion defect pits has a significant impact on the stress distribution of pipelines, so attention should be paid to the influence of corrosion pit depth when conducting pipeline safety assessments. During the process of increasing the depth ratio of corrosion defect pits from 0.1 to 0.8 in stages, the circumferential stress, radial stress, and Mises stress at the corrosion defect site on the pipe wall show an increasing trend. The circumferential stress at the corrosion defect pit before repair is similar to the Mises stress, while the radial stress is smaller than the previous two and the circumferential stress is the largest among the three. Before and after repair, the control stress at the corrosion defect of the pipeline is generally the circumferential stress, and the failure of the pipeline can be judged based on the circumferential stress. After repair, the inner lining of the GFRP protective composite pipe wall experienced stress redistributions at the original corrosion defect pit, and both the circumferential stress and Mises stress decreased, indicating a significant repair effect.