混凝土内锈蚀钢筋的漏磁信号分析

Magnetic flux leakage signal analysis of corroded reinforcing bar in concrete

将漏磁检测技术应用于混凝土内部钢筋的锈蚀检测中,以磁偶极子模型为理论依据,在对锈蚀钢筋进行数值模拟的基础上,完成了对10个试件的加速锈蚀、磁信号采集及分析.提出了基于磁偶极子模型的钢筋锈蚀损伤漏磁场空间分布计算理论,计算了锈蚀钢筋的漏磁场的空间分布,分析得到沿试件纵向的磁感应强度B_x-x曲线图和磁感应强度梯度K_x-x曲线图.数值模拟和试验结果表明:根据磁感应强度B_x-x曲线的峰值可半定量评估钢筋的锈蚀程度,根据磁感应强度梯度K_x-x曲线的零点间距可定量判断钢筋的锈蚀区域,且箍筋及混凝土保护层厚度对于钢筋锈蚀损伤检测的影响较小,可以忽略不计.

The magnetic flux leakage (MFL) technology was applied to detect the corrosion of steel bars inside the concrete. Based on the magnetic dipole model, the corroded steel bar was numerically analyzed. The specimens were corroded,and the MFL signals were acquired and analyzed. The MFL field distribution was calculated by the proposed calculation theory based on the magnetic dipole model. The B x-x curve of magnetic induction intensity and the K x-x curve of magnetic induction intensity gradient along the specimen longitudinal direction were obtained. The results of simulation and experiment show that the steel corrosion degree can be semi-quantitatively evaluated by the peak value of the B x-x curve.The area of steel corrosion can be quantitatively measured according to the zero point spacing of K x-x curve. The effects of stirrups and concrete cover thickness on the detection of steel corrosion can be negligible.