Characteristics of Acoustic emission amplitude and wave velocity in hydraulic concrete structures

Amplitude attenuation test and wave velocity attenuation test are used to analyze the characteristics of acoustic emission (AE) signals in hydraulic concrete structures. The attenuation curves of amplitude-distance and velocity-distance of acoustic wave in a hydraulic concrete structure were plotted by using pencil lead break (PLB) as AE simulation source. Amplitude-distance distribution of AE signal in hydraulic concrete structure better satisfies the logarithmic attenuation model, and the amplitude attenuation is up to 38dB during 1m propagation, so the AE sensor spacing should not exceed 1m. Three kinds of nonlinear fitting model are used to analyze the velocity - distance data. It is found that the Boltzmann sigmoidal curve fitting model has the highest fitting accuracy and the best fitting goodness, the Boltzmann sigmoidal curve can well reflect the three stages of the velocity-distance curve, which include the upper platform, wave velocity rapid attenuation zones, and the lower platform, so as to carry out the correction of the average wave speed under different propagation distances. The characteristics of amplitude attenuation and wave velocity attenuation can provide data basis and reference for subsequent AE detection of hydraulic concrete structures.