Simulation of large-scale experimental failure of flood defence systems

Embankments or otherwise known as levees or dikes are typical flood defence structures. Levees have allowed people to settle along rivers and low-lying countries where the risk of flooding is high. Although levees provide protection against floods, they are not exempt from being prone to failure. The risks posed by levee failure can be catastrophic. This makes it crucial to assess the consequences of levee failures. The limit equilibrium method (LEM) and finite element method (FEM) are two techniques capable of simulating levee failure. However, the former does not allow for a progressive simulation of the complete failure process, while the latter encounters convergence issues and cannot simulate large displacements. To overcome these issues, the material point method (MPM) is introduced. In this study, two numerical simulations are conducted to replicate an experimental slope failure of a full-scale earthen levee known as IJkDijk South Dike that took place in the Netherlands in 2012. The first simulation employed FEM for pre-failure analysis, while the second employed MPM for the post-failure analysis where large deformations are present. Before simulating the experiment, a basic slope was modelled as a benchmark to ensure consistency between the two different methods for simulating the same problem. This helped to validate post-failure analysis results which involved mapping of stresses from the onset of failure. Furthermore, sensitivity analysis was performed for the strength and consolidation parameters in the pre-failure analysis, as well as for the stiffness and assignment of the number of material points per element in the post-failure analysis. Overall, the models managed to capture the deep sliding failure mechanism reported in the experiment, with the MPM model permitting the evolution of the failure over time.