Methods of detectiоn a voids under concrete slabs of water faces of the dam of Novosibirsk hydrostation by the standing wave method

Using the example of the Novosibirsk hydrostation, the capabilities of the standing wave method to identify defects in the fastenings of water faces of dams of hydraulic structures are demonstrated. The accumulation of amplitude spectra of acoustic noise records allows one to determine the frequencies of the few first modes of standing compression waves generated by noise in concrete slabs. A sharp increase in the frequency of the lowest mode of standing waves is an indicator of the appearance of voids under the slabs or decompression of the base soil.