埋地管道杂散电流腐蚀及其数值模拟研究进展

Research progress in stray current corrosion and its numerical simulation for buried pipeline

杂散电流具有多源性特征,其腐蚀类型有直流、交流及地电流3种,其腐蚀强度大且集中于局部位置。杂散电流的成因有二:电流泄漏和电位梯度。直流杂散电流腐蚀的本质是电化学腐蚀的电解作用,而交流杂散电流的腐蚀机理有待进一步研究。目前采用的防护手段有:避开杂散电流干扰源、增大接地电阻、排流保护法、电化学方法防护、材料表面改性、加强日常维护和检修。针对杂散电流腐蚀问题的数值计算,目前主要采用有限元法和边界元法,其中边界元法应用更为广泛。当前主要通过现场电位观测法确定杂散电流腐蚀的保护方案,而通过数值计算和模型实验相结合的方式确定最佳保护方案将成为未来的发展趋势。针对土壤介质不均匀的情况,可采用分块边界元法提高计算精度。(表1,图1,参45)

Stray currents follow multi-source characteristics and can be divided into direct current, alternating current and ground current. They are subject to a large corrosion strength concentrated in a local position. There are two causes for stray currents, namely current leakage and potential gradient. Direct stray current corrosion is essentially electrolytic action of electrochemical corrosion, while corrosion mechanism of alternating stray current needs further studies. Current protection means adopted include avoidance of stray current interference source, increase of grounding resistance, electric drainage protection method, electrochemical protection method, material surface modification and enhancement of daily maintenance. Finite element method and boundary element method are mainly used for numerical calculations of stray current corrosion, of which the boundary element method is applied more widely. Field potential observation method is mainly used to determine a stray current corrosion protection program while it will become a future development trend to determine the optimum protection program by the combination of numerical calculations and model experiments. In the case of uneven soil media, blocked boundary element method can be used to improve calculation accuracy. （1 Table, 1 Figure, 45 References）