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Geodetic monitoring of earth-filled flood embankment subjected to variable loads

Kuras P., Ortyl Ł., Owerko T., Borecka A.

Reports on Geodesy and Geoinformatics

2018

Vol. 106

9--18

The article presents an example of supplementing geotechnical monitoring with geodetic observations. The experimental flood embankment built within the ISMOP project (Information Technology System of Levee Monitoring) was subjected to continuous monitoring based on built-in measuring sensors. The results of geodetic monitoring used for observation of earth-filled flood embankment subjected to external loads are presented in the paper. The tests were carried out on an experimental flood embankment forming a closed artificial water reservoir. The observations were carried out for two purposes. The first was long-term monitoring, which was aimed to determine the behaviour of the newly built embankment. The second purpose was to check the reaction of the levee to the simulated flood wave, caused by filling and draining the reservoir. In order to monitor the displacements of the earth-filled embankment, it was necessary to develop the proper methodology. For the needs of research works, an appropriate network of 5 reference points and 48 survey markers has been designed and established. The periodic measurements were carried out using precise robotic total station. The stability of the reference frame was each time checked and displacements of survey markers were determined based on it. The final results allow to reveal the reaction of levee to external loads. The displacement values were referred to the course of the filling and draining experiment to indicate the relationship between them. In the field of long-term monitoring the results clearly imply the dominance of displacements outside the reservoir for points located on the embankment, in contrast to points on the crest and foreground, which do not show significant movements. On the other hand, in the field of testing the embankment reaction to the flood wave, obtaining reliable results was possible thanks to high-accuracy geodetic measurements. Small displacement values, often at the level of their determination errors, were averaged for groups of points with the same height of foundation. A sizable number of points allows to perceive some tendencies and the relation between embankment soaking and its movement directions can be noticed. During periods when the levee was still saturated with water, slight movements outside the reservoir were revealed. On the other hand, the following period of drying caused movement in the opposite direction.

Zastosowanie metody konduktometrycznej do typowania stref o zmiennych parametrach filtracyjnych w obrębie podstawy wału przeciwpowodziowego

Cygal A., Stefaniuk M., Kret A., Klityński W.

Przegląd Geologiczny

2015

Vol. 63, nr 10/1

652--656

The need to continuously monitor the flood embankment is necessary to introduce the measurement methods which give quick results in crisis situations. The protection of embankments as well as the prevention from floods are not only associated with the examination of the body river levee. Experience suggests that one of the problems involves the unknown geotechnical conditions of the levee base. Unfortunately, point geotechnical surveys carried out with a big measurement step were not able to fully identify the lithology variation over larger areas. This is caused by the high cost of drilling shallow wells. The application of non-invasive geophysical methods allows the completion of geotechnical research, and supplies additional information about the variability of geological medium. The structure in the area of the former river beds creates favorable conditions for carrying out geophysical surveys dependent on the variability of geoelectrical properties of rocks. This problem is solved by the use of conductivity method on the 100 m long part of the flood bank. This is recommended for quick and non-invasive measurements. A complex interpretation of geotechnical, hydrogeological and geophysical data provided information about the variability of geoelectrical parameters over this area and therefore made it possible to identify areas prone for greater filtration during high water levels.