The geodetic detection of the variable load impact on the earth-filled structure

Abstract

This article concerns the evaluation of displacement monitoring referred to the earth-filled flood embankment using surveying and radar measurement techniques. The results allow to reveal the embankment reaction to the external loads. The results of long-term geodetic monitoring clearly imply the dominance of displacements directed outside for points located on the embankment slopes. The displacement values were also referred to the course of the changing water level representing a flood wave, in order to point out the mutual relationship between them. Horizontal displacements indicate that earth-filled embankments may behave to some extent like elastic structures. For the experiment, which covered determining the embankment response to the varying water level, ground-based radar interferometry was used as an alternative measurement technique. This selection was justified primarily by the submillimeter accuracy of the displacement measurement. However, the research required overcoming a few limitations, among which the atmosphere variability is the most important. This was taken into account by measuring the current atmospheric conditions and correcting the results by atmospheric delay. For the time intervals in which it was possible to compare surveying and radar measurement techniques, the displacement values were analyzed and referred to the current structure load resulting from the variable water level. A sizable number of the observations allow to perceive some tendencies, even if the displacement values were at the measurement uncertainty level. The movement trend is consistent for both methods. This was evidenced particularly by the compatibility of the considerable displacements detected for the points located in the area of presumed embankment failure. Moreover, the differences are within the limits of agreements determined on the basis of the Bland–Altman plot, which means that these two measurement methods could be used interchangeably.