Research On Intelligent Ultrasonic Testing Technology Of Coral Concrete Quality Of Island Reefs

Coral concrete is a new type of concrete made of coral aggregates instead of coarse aggregates and seawater instead of fresh water,it is of great significance to reduce the transportation cost of materials and shorten the construction period in the construction of islands and reefs.In practical engineering applications,the strength of coral aggregate is lower than that of cement mortar,which makes coral concrete show brittle failure characteristics,and there is no obvious damage before the failure,resulting in a greater safety hazard in its structure.In order to ensure the performance of coral concrete,it is necessary to conduct non-destructive testing to evaluate its structural properties.Ultrasonic testing technology is a very important method in the field of non-destructive testing technology.In this paper,the quality of coral concrete was tested and evaluated by ultrasonic testing technology,and the relationship between the acoustic parameters of coral concrete and its water-cement ratio and damage was analyzed.The main research contents and results are as follows:(1)The effect of water-cement ratio on the acoustic properties of coral concrete was studied.Coral concrete and ordinary concrete specimens with different water-cement ratios were made,and ultrasonic inspection comparison test were carried out.The test results show that the longitudinal wave velocity of coral concrete of the same age decreases with the increase of water-cement ratio;when the water-cement ratio is the same,the longitudinal wave velocity of coral concrete with an age of 28d is greater than that of 7d;the test results of ordinary concrete also conform to the above rules,but the longitudinal wave velocity of ordinary concrete is greater than that of coral concrete.(2)The acoustic properties of coral concrete under uniaxial loading was studied.Collected and analyzed the ultrasonic signals of cubic and prismatic coral concrete under different stress states,and extracted the acoustic characteristic parameters that can reflect the degree of damage from the acoustic parameters of the cubic concrete,which were defined as the wave velocity attenuation coefficient as and the amplitude attenuation coefficient βS,and then the ultrasonic signal acquisition and analysis of the two coral concretes were carried out.The Pearson correlation coefficient method was used to calculate the degree of correlation between the coda waves under different stresses and the coda waves under the initial stress,which was the correlation coefficient p.The results show that:as and βS will decrease with the increase of stress,and begin to change abruptly at about 80%of the ultimate stress;p can reflect the crack development state of the two kinds of coral concrete at various stages;When the stress σ/σ0 of the prism is more than 0.8,it can be seen that the curve of ρ/ρ0 has an obvious downward trend,and then a sudden change occurs;and when the stress σ/σ0 of the cube is greater than 0 and less than 0.4,the downward trend of the ρ/ρ0 curve can be seen;when σ/σ0 is more than 0.65,ρ/ρ0 decrease to less than 0.2 and approach to 0,which is weakly correlated with the waveform signal collected from the initial stress.(3)The intelligent ultrasonic testing technology software for coral concrete quality was developed.The main functions of the software include new construction,data acquisition,data analysis and data preservation.Among them,there are two calculation methods for data analysis:correlation coefficient calculation,amplitude standard deviation calculation,and visualization of the calculated results.The one-stop data processing function of "collection-processingvisualization" is realized,which can be used to detect the damage degree of coral concrete under uniaxial compression,and realizes intelligent real-time evaluation,which improve detection efficiency and reduce human error.In this paper,after calculating the longitudinal wave velocity and amplitude of coral concrete,the results can be used to evaluate the damage degree of coral concrete under uniaxial compression,and an intelligent ultrasonic detection software for coral concrete quality was written,which is conducive to realizing the intelligent quality of coral concrete.