DIAGNOSTICS OF A BASE OF RIGID PAVEMENT USING ELASTIC STANDING WAVES

Abstract

Тo ensure the safe operation of roads, periodic monitoring of the pavement is needs. In recent years to conduct such studies, methods of shallow geophysics are widely used. However, despite the variety of methods used to control the pavement and the problems solved with their help, the accuracy and reliability of the results obtained does not always correspond to the requirements. The article presents the results of field experiments that demonstrate the possibility of detecting cavities under a rigid pavement using flexural standing waves. The accumulation of amplitude spectra of a large number of noise records was used to isolate standing waves from the acoustic noise recorded on the surface of the pavement. It is shown that the joint visualization of the averaged spectra obtained during the profile observations of the cavity makes it possible to confidently identify several modes of flexural standing waves by alternation along the profile of nodes and antinodes at some frequencies. According to the area measurements, an amplitude distribution map of one of the modes of flexural standing waves over the cavity (a gully under the asphalt pavement) was constructed. At a qualitative level, this distribution is consistent with the results of computer simulation by using the finite element method. The fact that under the influence of acoustic noise in the pavement the flexural standing waves are formed which are absent in other places, indicates the absence of rigid contact at its lower boundary. Thus, the horizontal dimensions of the cavity can be estimated from the size of the area on which flexural standing waves are formed. In addition, the article shows that the analysis of vertical compressional standing waves arising in the pavement under the influence of noise, allows one to control the thickness of the pavement and to qualitatively assess the ratio of acoustic stiffness of the pavement and the underlying layer.