Abstract :
[en] Flood is one of the most serious natural disasters that affect human beings,
so how to effectively reduce flood damage to human beings is of vital im-
portance. One of the keys to reducing flood damage is to design buildings
effectively enough to withstand flooding and the impact of floating debris
on the structures.
Although, many studies exist to address the impact of floods on structures,
the impact of floating debris on the buildings and structures, i.e. wall or
bridge during flooding have not been fully addressed yet. Thus, the objec-
tive of this dissertation is to predict the trajectory of floating debris of rivers
during flooding and analyze its impact on the structures.
For achieving this goal, a numerical tool based on the mesh-less method of
Smoothed Particle Hydrodynamics (SPH), Discrete Element Method (DEM)
and Finite Element Method (FEM) is proposed in this dissertation. Where
SPH is employed to describe the fluid flow and DEM is employed to ob-
tain the contact force between the floating debris and structures. And a
coupling model of SPH and DEM is presented and implemented based on
the OpenFPM, a scalable and open C++ framework for particles and mesh
simulation in parallel. Buildings and structures are represented by Finite
Element Method (FEM) mesh, for which impact with floating debris is de-
termined. These contacts of floating debris cause forces at the positions of
impact, e.g. mechanical load and are evaluated by using commercial Finite
Element Analysis (FEA) software Abaqus.
As a result, a numerical tool combing the SPH-DEM and FEA is presented
in this dissertation It is worth to notice, that treating the inlet/outlet con-
dition in SPH is a challenging issue due to its Lagrangian nature. A suitable
boundary treatment for the inlet / outlet condition in SPH for river flooding
problem in 3D is unavailable in literatures. Thus, this dissertation extended
the open boundary treatment for SPH using semi-analytical conditions and
Riemann solver in 2D (Ferrand et al., 2017) to 3D. Which in results, a new
open boundary treatment that is suitable for describing the inlet/outlet
condition of SPH in 3D is presented and applied to describe the inlet/outlet
condition in this dissertation.
The numerical tool is applied to study the scenario of floating trees, trans-
porting in the Mosel river and hitting the flood control wall at Kesten town
in the west Germany during flooding. As the result of simulation shows,
the floating trees are driven by the river and heading to the downstream
and eventually collide with the flood control wall. This impact causes the
flood control wall crack from the position of impact. Which means that the
flood control wall is not capable of standing the impact of floating trees that
transported in the river.
