Abstract

Acoustic Emission and Seismic Emission Monitoring of the Foundation of Hydroelectric Power Station Located on Soft Soils

N.Vilchinska, Dz.Slapyms (Energo Lab, Technical Center, Riga, Latvia)

e-mail: vilcinska@hotmail.com

If elastic waves are to be propagated in a medium with inhomogeneities (localized defects, stratification, cracks) the characteristics of the information signal, for example, velocity of propagation, amplitude, and spectral contents, can change their parameters [1]. The sensitivity of these parameters to such inhomogeneities depends, in particular, on a wavelength of the probing signal and this may be used to assess the quality of concrete. An efficient solution of the last mentioned problem consists in the development of techniques and equipment based on nonlinear acoustics, adapted to physical and mechanical properties of concrete and to the sizes of expected structural inhomogeneities. The technique employed consists in generation of acoustic signals at a certain frequency by the piezoelectric effect and detection of information signals at several points distributed on the surface of item under evaluation. The calculation of defect sizes, the depth and location of a stratification plane in concrete of massive constructions is made using a number of characteristics of detected signals. These characteristics are processed with a specially developed algorithm. An important advantage of technique developed in this study is eliminating the necessity for auxiliary holes drilled to perform the measurements [2].

References: 1. Truell R., Elbaum C., and Chick B. B., Ultrasonics Methods in Solid State Physics, New York: Academic Press, 1969 (Translated in Russian in 1972, Moscow: Publishing House "Mir"). 2. USSR Patent No. 1413516. The device for quality control of materials, by Serikov J.A., Serikov S.J, and Boguslavski M.E.

Section : 3