Numerical interpretation of regressive localized internal erosion in a real-scale levee physical model

This paper presents the numerical interpretation of a recent experiment on a real-scale levee physical model, in order to investigate the process of Backward Erosion Piping (BEP) and validate a recently proposed finite element formula- tion able to model both the simultaneous processes observed in backward erosion piping, i.e. the propagation of the pipe tip and the enlargement of the conduit cross-section, as well as the time-dependent effects. In previous papers, the numerical formulation already demonstrated its ability in reproducing available experimental data of full-scale physical models of levees, e.g. for the IJkdijk and for the Delta Flume tests. In the present work, as a further validation for the aforementioned formulation, we consider the numerical interpretation of the regressive localized internal erosion observed in the newly constructed real-scale levee at the Flood Proof Holland facility test site in Delft, The Netherlands. This test was mainly focused on the experimental evaluation of the time-dependent effects typically observed in these phenomena. To this purpose the levee foun- dation was equipped with an effective and accurate water pressure monitoring system. In view of its ability in modeling the time-dependent effects in backward erosion piping, the aforementioned formulation was considered as the proper one for the numerical interpretation of the test. A good agreement between calcu- lated and measured piezometric heads and pipe tip propagations was obtained.