Author(s): Berit Finklenburg; Elena-Maria Klopries; Holger Schuttrumpf

Linked Author(s): Berit Finklenburg, Holger Schüttrumpf

Keywords: Geotextile tube; Resilient dike; Experimental modeling

Abstract: Due to climate change, flood events may increase in frequency and magnitude. River dikes built according to the state of the art usually breach due to overflow or piping causing significant damage to humans and infrastructure in the flooded area. In order to adapt to extreme flood events, resilient flood protection structures are required. Such structures should not only minimize the destructive potential of flood events, but need to be designed resource efficiently ensuring low environmental impact. Dikes made out of stacked soil-filled geotextile tubes represent a promising way of meeting the above-mentioned challenges. Innovative machine technology enables wrapping, filling, and placing the tubes on-site within an integrated continuous process. Covered with earth and vegetation, the tube dikes blend into the landscape just like conventional dikes. The geotextile package protects the filling material from inner and outer erosion and thus prevents the dike from breaching due to overflow or piping. The erosion protection enables steeper slopes reducing the amount of filling material as well as the land consumption. Additionally, the requirements on the filling material are lower and thus locally available material can be used for implementation of short transport ways along with low cost and reduced environmental impact. By now, geotextile tubes are filled hydraulically and used mainly in coastal constructions such as groynes, breakwaters, sea dikes or artificial islands. Stability calculations are thus based on the pumping pressure during the filling process and on wave loads during the design life. For dry-filled geotextile tubes used in river dikes, however, there is a lack of experience and established stability calculations. Hence, the aim of our investigation was the analysis of the 2D- und 3D-behaviour of dry-filled, stacked geotextile tubes during seepage and overflow under systematic variation of the initial conditions. To meet the requirements, we set up 2D-experiments in a 2 m wide dike model as well as 3D-experiments in a 29.8 m wide dike basin. During the experiments, we systematically varied the parameters filling material, degree of filling, number of geotextile layers, number of tubes, load type, load strength, and load duration. In order to determine design rules for geotextile tube dikes, we measured the flow depth, seepage level, seepage flow, tube shape, and material transport using ultrasonic probes, pressure gauges, 2D-LiDaR-Sensor, and soil sampling cylinder in combination with sieving analysis. The results in form of failure mechanisms and failure modes lead to hydraulic stability formulae serving as basis for design recommendations and stability assessments in comparison to conventional river dikes.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022164

Year: 2022