Characteristics of wave velocity and power spectral density of hole-containing specimens under water conditions

In order to study the ultrasonic characteristics of the pore samples with different water contents,the uniaxial compression test of the pore samples under different water conditions was carried out,and the wave velocity during compression was measured by RSM-SY7 ultrasonic system. Transmission waveform of a sample containing pores with different water contents was obtained. The results show that the average initial wave velocity of the specimens decreases gradually with the increase of water content. During the destruction of the hole-containing specimens,the change of wave velocity has three stages including stable stage,slightly decreasing stage and rapidly decreasing stage. The dura- tion of the stable and rapidly decreasing stages increases with the water content decrease;the duration of the slight de- crease stage decreases with the water content decrease. The power spectral density also decays as the specimen breaks. The degree of attenuation is affected by the water content. The higher the water content,the more balanced attenuation of the power spectral density in each frequency,the smaller the attenuation at the peak,and the more similar attenua- tion at different times.