基于单模-多模-单模光纤的钢筋腐蚀监测技术

Steel Bar Corrosion Monitoring Based on Single Mode-Multimode-Single Mode Optical Fiber

关键词:  单模-多模-单模光纤  钢筋腐蚀监测  特征波长  线性极化阻抗

Key words:  single mode-multimode-single mode （SMS） optical fiber  steel bar corrosion monitoring  characteristic wavelength  linear polarization resistance

摘要:

提出了一种利用单模-多模-单模（SMS）光纤进行钢筋腐蚀监测的方法.首先，采用长度分别为2、3、4 cm的3组无芯光纤（NCF）作为多模光纤，制备单模-多模-单模（SMS）光纤传感器；然后，将贴有SMS光纤传感器的钢筋置于质量分数为3.5%的NaCl溶液中进行腐蚀，并用光谱仪实时监测钢筋腐蚀过程中SMS光纤光谱的变化，同时采用开路电位和线性极化阻抗测量钢筋腐蚀电位和腐蚀电流密度，计算钢筋累积腐蚀量.结果表明：钢筋腐蚀量与特征波长的偏移量呈3次函数关系，SMS光纤监测钢筋腐蚀的灵敏度随着多模光纤长度的增加而提高，且随着腐蚀时间的增加而先增大后减小.

Abstract:

A method of steel bar corrosion monitoring used single mode-multimode-single mode optical fiber was proposed. Firstly， three lengths of non-core fiber （NCF） were used as multimode fiber to make SMS optical fiber sensor， including 2 cm， 3 cm and 4 cm. Then， the fiber was directly placed on the polished side surface of a steel bar， and immersed in 3.5% NaCl solution for corrosion test. The change of light spectra was continuously monitored with an optical spectral analyzer （OSA）， and the corrosion potential and corrosion current density of steel bar was measured with open circuit potential and linear polarization resistance， respectively， based on which the accumulative corrosion-induced mass loss of steel bar was calculated. Results indicate that a cubic relationship is present between the mass loss of steel bar and the change in the characteristic wavelength of SMS optical fiber. The sensitivity of SMS optical fiber for corrosion monitoring increases with an increase of the length of the multimode fiber segment， while it first increases and then decreases with the increase of corrosion time.