Exploration of underground buried objects by noncontact acoustic inspection using normalized SSE analysis

Using our noncontact acoustic inspection, the exploration of a buried object in the ground was performed in a non-contact and remote manner. Conventionally, SSE analysis has been applied to detect internal defects (cavities, cracks, peeling, etc.) of solid such as concrete. In particular, SSE can find resonance frequency band of internal defects. This time, it was applied to soil buried object. The accuracy of SSE to detect the resonance frequencies was improved by removing the influence of relatively large vibration velocities, caught on a laser Doppler vibrometer, due to fine particles on the surface of ground by statistical method. Normalization of SSE was examined so that SSE values are not affected by different objects or measuring conditions.