Detection And Application Of Impact Elastic Wave Technology Inspection Of Concrete Under Water Environment

The quantity and scale of hydraulic Engineering in China are enormous,which have produced huge economic and social benefits,and the detection and safety evaluation of hydraulic structures are of critical importance.Among the numerous nondestructive detection method,impact-echo methed is more and more widely applied in the inspection of concrete structures At the same time,the hydraulic structures such as dams and docks have been served for a long time in the water environment,but relatively few studies on the use of the impact elastic wave of water content of concrete among the current research situations.Therefore,this paper elaborates the relationship between with water content and elastic wave velocity by indoor laboratory experiments and the mechanism of influencing elastic wave velocity,comparing the difference between the elastic wave and the ultrasonic characteristics of the contrete.The relationship between the spectral characteristics of the elastic wave and the water content is analyzed.Based on the test results,the modified model of the elastic velocity of the concrete is established.The research results can provide reference for the safety evaluation of the concrete structure in the water environment.Through a large number of laboratory tests,the relationship between the concrete moisture content and the elastic wave velocity,impact elastic wave spectrum and ultrasonic velocity were explored.The main content is summarized as below:(1)Conducting the water environment of concrete impact-echo and ultrasonic elastic wave experiment,analysis of the elastic wave velocity and frequency spectrum characteristics and the ultrasonic wave velocity under different moisture content.The experimental results show that the moisture content has a certain relationship with ultrasonic wave velocity and elastic wave velocity without any additional initial damage?(2)Using concrete under the different liquid environment to do the impact-echo wave experiments and the ultrasonic experiments,study different bulk modulus of the liquid under the influence of impact-echo wave velocity and ultrasonic wave velocity,the experimental results shows that the different volumes of liquid volume have different effects on impact-echo wave velocity and ultrasonic wave velocity.(3)The experiment of impact-echo waves and ultrasonic waves in different damaged conditions concrete was analyzed.The evaluation curve of moisture content and elastic wave velocity and ultrasonic wave velocity were given by the experimental velocity data.In terms of spectrum characteristics,there is existing a certain linear relationship between moisture content and frequency spectrum area,the results can provide a new idea for using the impact-echo wave to detect the concrete moisture content.(4)Ansys finite element analysis software was used to simulate impact response on the three-dimensional model of concrete.The propagation process of elastic wave in concrete was simulated and compared with the experimental results.The feasibility of using numerical method to analyze the impact resistance of concrete was verified.