GGU-3D-SSFLOW: Step 1: Define the system
We will investigate a flood protection embankment with a 1 m thick sealing layer in the embankment foreland and on the slope towards the water. There is a weak area in the cover layer of the embankment foreland covering an area of 8.33 m · 10.0 m. The system is symmetrical perpendicular to the embankment axis, so only half the system need by investigated. The system looks like this in a 3-dimensional view:
The visible longitudinal side of the system is the symmetry plane. It looks like this in section:
Figure 3 Worked example in section
Perpendicular to the section the weak area has a width of 10.0 m (5.0 m in the symmetrical system). The embankment will be modelled along a length of 40.0 m (20 m in the symmetrical system). The dimensions have been selected so that the subsequent mesh generation remains simple and does not have too much unnecessary ballast.
The following permeabilities are given:
Embankment core and subsurface: k = 10-4 m/s
Sealing layer: k = 10-7 m/s
The upstream pondage of the embankment is at 15 m AD. As on many proprietary embankments, no drainage system is installed on the air side. Drainage is by means of the hinterland, which is at 10 m AD.
The discharge through the embankment will be determined for the following cases:
Case A with weak area
Case B without weak area