基于扩展磁荷模型的埋地管道弱磁检测方法研究

Weak magnetic detection method on the buried pipeline based on the extended magnetic charge model

为了提高弱磁检测方法对埋地管道早期损伤诊断的有效性,进一步明确检测信号与应力和缺陷之间的定量关系,构建了考虑力磁耦合效应和位错钉扎效应的扩展磁荷模型,研究了多种管道异常状况引起的弱磁检测信号变化规律,利用工程检测实验验证了该模型的有效性。研究结果表明,在体积型凹坑缺陷、面积型裂纹缺陷和焊缝缺陷处,梯度模量G_(M)均出现显著的对称尖峰畸变,且其峰值随缺陷尺寸的增加而增大,其中当量深度的影响更为显著;焊缝错边缺陷对G_(M)峰型和峰值的影响显著,而咬边缺陷的影响不明显;工程实测数据与理论计算数据的最大位置误差≤1 m,最大峰值误差≤15%,均在工程检测的可接受范围内。

An extended magnetic charge model considering the magneto-mechanical coupling effect and dislocation pinning effect is constructed to improve the effectiveness of the weak magnetic detection method for early damage diagnosis of buried pipelines,and further clarify the quantitative relationship between detection signals and stress and defects.The variations of weak magnetic detection signals caused by various abnormal conditions of pipelines are studied.The effectiveness of the model is evaluated by engineering detection experiments.Research results show that the gradient modulus G_(M) has significant symmetrical peak distortion at the volume pit defect,area crack defect or weld defect.The peak value of the gradient modulus G_(M) increases with the increase of defect size,especially the equivalent depth.The influence of weld misalignment defect on the peak shape and peak value of G_(M) is significant,while the influence of undercut defect is not obvious.Comparing the engineering measured data and theoretical calculation data,the maximum position error is ≤1 m,and the maximum peak error is ≤ 15%,which are both within the acceptable range of engineering detection.