Acoustic emission characteristics in deterioration behavior of dam concrete under post-peak cyclic test

Abstract

This paper presents the analysis of the deterioration in dam concrete by using acoustic emission (AE). The post-peak cyclic bending tests were carried out. The AE counts and AE hit were used to analyse the damage. The “Kaiser effect” in the post-peak field was observed. However, the results showed a weak correlation between the structural deterioration and the AE count, and it was found that the change of loading rate would also make the AE hits and counts change greatly, indicating that it is insufficient to rely only on these traditional AE parameters to characterize the deterioration process of the structure. Then, the frequency analysis based on peak frequency was conducted in order to better characterize the structural deterioration process. The principal component analysis and the K-means clustering method were combined to classify the signals. Two types of specific signals which were more sensitive to the structure degradation behavior have been found, and showed promise for structural deterioration characterization. The fracture type analysis indicated that the specific signals with low peak frequency and high RT value may have strong correlation with strong shear behavior, while the signals with high peak frequency and high RT value have strong correlation with micro-crack opening.