混凝土裂缝深度的激光超声探测方法  

Laser ultrasonic detection method for concrete crack depth

作　　者：刘学增[1] 段俊铭 桑运龙[1,3] 赖浩然 周若阳 LIU Xuezeng;DUAN Junming;SANG Yunlong;LAI Haoran;ZHOU Ruoyang(Civil Engineering Information Technology Research Center of Ministry of Education,Tongji University,Shanghai 200092,China;Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;Shanghai Tongyan Civil Engineering Technology Co.Ltd.,Shanghai 200092,China;China State Construction Engineering Corporation,Beijing 100029,China)

机构地区：[1]同济大学土木信息技术教育部工程研究中心,上海200092 [2]同济大学地下建筑与工程系,上海200092 [3]上海同岩土木工程科技股份有限公司,上海200092 [4]中国建筑股份有限公司,北京100029

出　　处：《中南大学学报（自然科学版）》2021年第3期839-847,共9页Journal of Central South University:Science and Technology

基　　金：国家重点基础研究发展规划(973计划)项目(2015CB057806);国家自然科学基金面上项目(51878497);贵州省科学技术厅重大科技专项项目(黔科合重大专项字[2018]3011);浙江省交通运输厅科技项目(2018011)。

摘　　要：为探究激光超声技术检测混凝土裂缝深度的可行性,首先,建立平面应变的有限元模型,研究激光激发的表面波与混凝土表面裂缝的作用规律;其次,分析表面波与裂缝前沿(波与裂缝最先作用的纵向边沿)作用的散射回波特征,讨论裂缝深度对散射回波特征点时间差的影响;最后,在自主研制的激光超声试验平台上,采用激光扫描混凝土表面激发声场、表面波探头接收信号的方法,分析裂缝深度分别为1,2和3 cm混凝土试块的时域波形信号。研究结果表明:裂缝前沿棱角作为一个次声源与表面波作用时发生明显反射,并在时域波形信号中产生了滞后于反射表面波的波峰波谷特征点波形;波峰波谷特征点到达时间差随裂缝深度增大呈线性增长,由此可根据裂缝前沿与表面波作用产生的散射回波特征实现混凝土裂缝深度的定量检测;物理试验中混凝土裂缝与表面波作用表现出相同规律,并结合数值模拟结果建立了检测裂缝深度的线性公式,试验检测裂缝精度最高可达90%。The purpose of the study is to explore the feasibility of detecting concrete crack depth by laser ultrasonic technology.Firstly,plane strain finite element model was established to study the interaction law between laser-induced surface wave and concrete surface crack.Secondly,the scattering echo characteristic of surface wave interacting with crack front(the longitudinal edge where the wave first interacted with the crack)was analyzed,and the effect of crack depth on the time difference of scattering echo characteristic point was discussed.Finally,the time domain waveform signals of concrete specimens with crack depth of 1,2 and 3 cm were analyzed by the method of laser scanning concrete surface excited sound field and received signal with surface wave probe on the self-developed laser ultrasonic test platform.The results show that the edge of crack front reflect obviously as an infrasound source when interacting with surface wave,and the wave peak and trough characteristic point waveform that lag behind the reflected surface wave is produced in the time domain waveform signal.The arrival time difference of wave peak and trough characteristic point increases linearly with the increase of crack depth,which can realize the quantitative detection of concrete crack depth based on the scattering echo characteristics generated by the interaction between crack front and surface wave.In the physical test,the concrete crack and surface wave show the same action law,and a linear formula for detecting crack depth is established by combining with the numerical simulation results,and the test detection accuracy can reach 90%.

关 键 词：混凝土裂缝 深度检测 激光超声 表面波 数值模拟与试验 

分 类 号：TU37[建筑科学—结构工程]