DETECTION OF INTERNAL DEFECTS IN SHOTCRETE SPECIMENS BY NONCONTACT ACOUSTIC DETECTION METHOD

Abstract

 The noncontact acoustic inspection method using acoustic irradiation induced vibration and laser Doppler vibrometer can remotely detect internal defects in concrete. However, fundamental verification experiments using shotcrete specimens have not been conducted for shotcrete, which has an uneven measurement surface. In this study, a shotcrete specimen was fabricated and a basic fundamental experiment using the noncontact acoustic inspection method was conducted. The experimental results show that defects can be detected in the same way as in the previous demonstration test conducted in the ceiling of a large underground cavern where an underground power plant is located.