Experimental study on the process behavior of Backward Erosion Piping in levee and dam foundations (X-BEP)

• Applicant: Professor Dr. Jürgen Stamm
• Subject Area: Geotechnics, Hydraulic Engineering
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 567279823

Flood risk reduction strategies are diverse, a common mitigation measure is the use of structural flood protection systems such as levees (also called dikes or embankments) and dams. Failure of these flood defenses can be caused by a number of failure mechanisms such as overtopping, slope instability or internal erosion. Backward erosion piping (BEP) is a specific internal erosion type of failure, which has accounted for 14 % - 15 % of the historic levee and dam failures worldwide. During the 2013 floods in Germany, it was also one of the dominant failure mechanisms of the multiple levee breaches. During high water events, groundwater flow can cause sand grains to erode from the foundation leading to the formation of one or multiple erosion pipes from the downstream towards the upstream side, called backward erosion piping. The main objective of the X-BEP project is to improve the description of the complex BEP erosion process and to derive erosion criteria for the primary erosion acting on the pipe tip and the secondary erosion acting on the pipe wall in order to use them in reliable prediction methods, using an innovative experimental setup. The reliable prediction of BEP has not been possible to date, as the mechanisms that describe the formation and progression of piping erosion are incompletely understood. A validated, generally recognized BEP method for the application in engineering practice does not exist, which is mainly due to the uncertain definition of the erosion criteria. To achieve an accurate prediction of BEP, it is necessary to apply primary and secondary erosion criteria. The question of whether the onset of the grain mobilization depend on upward seepage entering the pipe and its tip requires further study. For this purpose, systematic laboratory experiments are carried out and applied to a 3D-hydronumerical simulation (FEM) in order to better understand the erosion-determining conditions at the tip and along the backward erosion pipe.

• DFG Programme: Research Grants