Wave Velocity and Power Spectral Density of Hole-Containing Specimens with Different Moisture Content under Uniaxial Compression

The gas drainage borehole is a typical hole-containing structure, and its failure is similar to the hole-containing specimen. To study the characteristics of wave velocity and power spectral density of the hole-containing specimens with different moisture content, an ultrasonic test of the hole-containing specimens during destruction was carried out. A waveform with different moisture contents was recorded by the RSM-SY7 system. The wave velocity and power spectral density was calculated to analyze its relationship with moisture content and degree of damage. The results show that the wave velocity of the hole-containing specimens gradually decreases during the destruction. There were 3 stages of attenuation of wave velocity during the destruction, which were stable, slightly reduced, and rapidly decreasing stages. Changes in moisture content would cause changes of duration of the three stages. The power spectral density gradually decreases during the destruction. The moisture content affected the attenuation mode of the power spectral density and the amount of attenuation. In the detecting of the gas borehole, the wave velocity and the power spectral density can be used to locate the damage area. This research provides a theoretical basis for detection engineering.