Understanding Flow Slides in Flood Defences
Research Summary
During a flow slide, large amounts of soil move down an underwater slope. A flow slide is able to remove an entire dike or dune section which poses a severe threat to the water safety of low-lying countries.
The ability to predict flow slides is an important asset for the design of flood defence measures, their construction, maintenance and safety assessment; even more so in view of intensifying land use and the impact of climate change on low-lying coastal areas worldwide.
Flow slides are not yet well understood. Their study requires an integrated approach of fluid and soil mechanics; soil movement induces turbulent water motion which in turn interacts with the eroding soil surface. Currently, such an integrated approach is lacking. Studies so far mostly rely on empirical approaches that apply to specific circumstances only and use considerable simplifications. Physical experiments involve high costs as scale effects necessitate large test facilities and such tests often only allow predictions for specific projects. This makes the safety assessment of flood defences and the development of measures to prevent flow slides difficult and costly.
In the proposed interdisciplinary project, an integrated numerical solution for the simulation of underwater flow slides from initiation up to deposition of sediments will be developed through enhancement of a numerical method, the so-called material point method (MPM). Laboratory experiments will be performed to gain deeper insight into soil and fluid mechanical processes that occur at the onset of and during flow slides. They further serve for the validation of the developed numerical solution method. New physics-based models for soil-water interaction, soil heterogeneity and turbulent flow as relevant to flow slides will be formulated and existing models will be extended. They will be translated into purpose-built, efficient algorithms to be integrated into available Anura3D MPM software.
