基于激光诱导击穿光谱的混凝土氯元素分布测量方法  

Measurement of Chlorine Distribution in Concrete Based on Laser-Induced Breakdown Spectroscopy

作　　者：张智[1] 郭歆宇 杭玉桦 邱岩 吴坚[1] 孙浩 周颖 李京徽 梅金娜[2] 廖开星 ZHANG Zhi;GUO Xin-yu;HANG Yu-hua;QIU Yan;WU Jian;SUN Hao;ZHOU Ying;LI Jing-hui;MEI Jin-na;LIAO Kai-xing(State Key Laboratory of Electrical Insulation and Power Equipment,Xi'an Jiaotong University,Xi'an 710049,China;Suzhou Nuclear Power Research Institute,Suzhou 215004,China)

机构地区：[1]西安交通大学,电气绝缘与电力设备国家重点实验室,陕西西安710049 [2]苏州热工研究院有限公司,江苏苏州215004

出　　处：《光谱学与光谱分析》2024年第3期632-640,共9页Spectroscopy and Spectral Analysis

基　　金：国家重点研发计划先进结构与复合材料重点专项(2021YFB3703200)资助。

摘　　要：氯元素会对混凝土结构产生侵蚀,引起结构内部的钢筋锈蚀,导致混凝土开裂,破坏结构的完整性。化学滴定等常规的混凝土中氯元素含量测量方法存在操作复杂、检测速度慢等问题。激光诱导击穿光谱(LIBS)具有无须样品预处理、二维扫描检测和原位定点分析等优势,但其用于混凝土中的氯元素含量测量仍存在氯元素定量限难以降低、非水泥成分对氯元素二维分布测量结果的影响等问题。面向核电站混凝土构筑物中氯元素含量现场快速检测的需求,研究了氯元素含量分布的双脉冲激光诱导击穿光谱检测方法,进一步评估了核电站混凝土模拟样品渗透面中氯离子的侵蚀状况。首先,分别采用内标法、主成分回归和支持向量回归建立氯元素定标模型,基于内标法得到的氯元素检测限为0.006 02 wt%、定量限为0.018 06 wt%,并采用留一法交叉验证法来评估三种模型的预测性能。其次,为了排除非水泥基质对氯元素检测的影响,分别建立了结合主成分分析的逻辑回归分类和支持向量机分类模型对混凝土中的水泥和骨料进行精确识别。同时选取Si、 Ca、 O三种元素组合的支持向量机模型的分类效果最优,其对总体组分识别的准确率达到了98.20%,其中骨料识别准确率97.84%、水泥识别准确率为98.33%。最后,基于主成分回归定标模型针对侵蚀15和30 d的混凝土渗透面的氯含量进行二维分布测量,两种样品的平均预测Cl含量均在约2 mm处达到最大值分别为0.890 wt%和0.599 wt%,结果与电位滴定法一致。综上,基于双脉冲激光诱导击穿光谱检测方法,在30 mJ的总能量下实现了氯元素检测限达0.006 02 wt%,实现了混凝土中骨料和水泥的精确识别,获得了混凝土侵蚀渗透面的氯元素含量二维分布,为核电站混凝土构筑物氯元素含量快速检测的现场应用提供了工程化解决方案。Chloride ions will corrode the concrete structure,cause the corrosion of the reinforcement inside the structure,lead to concrete cracking,and destroy the structure s integrity.Conventional chlorine content measurement methods,such as chemical titration,have many problems,such as complicated operation and slow detection speed.Laser-induced breakdown spectroscopy(LIBS)has the advantages of no sample pretreatment required,two-dimensional scanning detection and in-situ fixed-point analysis.However,there are still some problems in the measurement of chlorine content in concrete,such as the difficulty in reducing the limit of chlorine quantification and the influence of non-cement components on the measurement results of the two-dimensional distribution of chlorine.In order to meet the application requirements of rapid detection of chlorine content in concrete structures of nuclear power plants,a method for detecting chlorine content distribution by dual-pulse LIBS is studied,and the erosion status of chloride ions in simulated concrete samples of nuclear power plants is evaluated in the paper.Firstly,the calibration models of chlorine are established by internal standard(IS),Principal Component Regression(PCR)and Support Vector Regression(SVR).The LOD and LOQ of chlorine calculated by the IS method are 0.00602 wt%and 0.01806 wt%respectively.The Leave-One-Out Cross-Validation(LOOCV)method is used to evaluate the prediction performance of the three calibration models.Secondly,to exclude the influence of the non-cement matrix on chlorine detection,Logistic Regression combined with Principal Component Analysis(PCA)and SVM classification are established to identify aggregate and cement in concrete.The SVM model with the combination of Si,Ca and O has the best classification effect,and its recognition accuracy of the total components reaches 98.20%,including 97.84%for aggregate and 98.33%for cement.Finally,the quantitative analysis of chlorine in the concrete erosion surface corroded for 15 and 30 days iscarried out aPCR ca

关 键 词：激光诱导击穿光谱 混凝土 氯 组分识别 二维扫描 

分 类 号：O433.4[机械工程—光学工程]