城镇燃气钢质管道受轨道交通电磁干扰测试与评价方法研究

【作者】 刘菊银；

【导师】 王新华；

【作者基本信息】 北京工业大学 ， 机械设计及理论， 2009， 硕士

【摘要】 随着我国地铁等轨道交通的蓬勃发展以及城镇燃气的普及使用,由此而凸显的埋地燃气钢质管道干扰电流腐蚀问题愈来愈引起了人们的关注。调查显示,我国90%以上的城镇埋地燃气钢质管道防腐层破损、剥离以及腐蚀穿孔等缺陷均由地铁等轨道交通泄漏到土壤中的动态干扰电流所引发,不仅造成了巨大的国民经济损失,同时也给人民的生命财产安全带来了隐患。在我国,燃气管道的建设始于20世纪50年代,地铁轨道交通的发展历史也才仅仅40年。因此,对埋地燃气钢质管道的轨道交通电磁干扰腐蚀问题尚未进行深入研究。同时,由于埋地燃气钢质管道埋设现场环境恶劣且复杂多变,导致现有技术与设备无法较好地应用于城镇埋地燃气钢质管道的电磁干扰检测与评价。因此,为了保障管道的安全运行并及时对受干扰的管道采取防护措施,对城镇埋地燃气钢质管道所受的轨道交通电磁干扰情况进行有效测试与评价势在必行。课题围绕该任务开展了理论与实验研究,取得了以下研究成果:通过对现有检测技术的比较分析,并针对轨道交通电磁干扰的动态变化特性,提出了管地电位连续动态监测技术。在实验研究的基础上,根据管地电位波动情况与干扰电流的关系,初步估计了管道受到的动态电磁干扰严重性。基于轨道交通动态电磁干扰原理,提出了实验室动态直流电磁干扰与交流电磁干扰腐蚀实验方案。搭建了动态电磁干扰下的金属管道加速腐蚀实验平台,研究了不同物化性质的土壤、不同特性的动态干扰电流对管道腐蚀速率的影响规律,以及干扰电流与管地电位波动范围之间的关系。通过数字图像处理技术提取腐蚀形貌图像的腐蚀特征,并应用分形几何理论,计算腐蚀形貌分形维数。研究表明,动态电磁干扰造成的管体腐蚀形貌具有分形特征,分形维数可作为定量描述腐蚀形貌特征的参数。同时,以实验研究为基础,建立了分形维数与腐蚀速率之间的数学关系式。采用LabVIEW与Microsoft SQL数据库、MATLAB、Visual C++结合的方法开发了埋地燃气钢质管道电磁干扰测试与评价软件。软件实现了数据实时显示、信号频域测量、数据统计计算、.txt文件存储与回放、数据库存储与条件查询、删除、干扰严重性判断等功能,并通过提取腐蚀形貌和计算腐蚀表面分形维数,估计了管道破损点处的干扰电流大小,并预测了管道的剩余寿命。更多还原

【Abstract】 As the flourishing development of the subway traffic and the common usage of urban gas, the electromagnetic interference and corrosion to buried gas pipe-lines attract more and more attention now. Investigation shows that, more than 90% urban buried gas pipe-lines’defects and leakage are caused by rail traffic disturbing current, which results great loss to national economy and damages the pipe-lines’safe operation seriously.In our country, the gas pipe-lines are developed in the 1950s, and the establishment of subway traffic has its only 40 years’history, so thorough research on dynamic current interference and corrosion has not been performed until now. Due to the complexity and variability of the field environment, current detection techniques and instruments can not be applied in the detection of the dynamic disturbing current on buried gas pipe-lines and the evaluation of the severity of the interference. So to find a dependable detection and evaluation method is the guarantee of the safety operation of buried gas pipe-lines. This subject carries out the theoretical and experimental research centering on this task and completes the main work as following.By the contrast with current detection techniques and according to the dynamic characteristics of subway electromagnetic interference, the pipe-to-soil potential sequential dynamical monitoring technology is put forward. On the base of lab experimental research and according to the fluctuation conditions of the pipe-to-soil potential, the severity of the electromagnetic interference is estimated initially.Subway electromagnetic interference and corrosion experimental model is built based on the principle of subway electromagnetic interference. The experimental platforms of DC and AC electromagnetic interference to pipes are established in the lab, and the inference rules of different soils and disturbing currents are researched, and the relationship between pipe-to-soil potential and disturbing current is explored here.Images of surface corrosion morphologys are acquired, and then corrosion characteristics through the technology of digital image processing are obtained. Based on the fractal theory, surface corrosion morphologys have characteristics with fractal and the fractal dimension can be considered as a parameter for describing complexity quantitatively.The software is developed for pipe-to-soil potential dynamic monitoring and corrosion evaluation using LabVIEW, Microsoft SQL database and C++. It can realize the real-time monitoring for pipe-to-soil potential. Meanwhile, it can realize format documents saving and calling back, database saving and conditional inquiry, then the severity of interference is judged and the remaining life of the pipe is predicted at last. The residual service life of the pipe and the magnitude of the disturbing current density can be estimated by extracting the corrosion morphologys and calculating the fractal dimension.更多还原