GGU-STABILITY: "Define search grid" menu item
- Matthias Jusko
A description of this menu item can be found under "Worked example 2: Data input via editor/Step 4: Define slip circles (Ex. 2)/Define search grid". Further examples below will clarify procedure for defining the search grid.
Select a centre-point array by going to the menu item "Centre-points/In rectangle".
Using this menu item to define the search grid the following dialog box opens. If there is any uncertainty in terms of the search, always select the "Horizontal tangents" search grid and a larger number of radii (40 or more), depending on your safety requirements.
After leaving the dialog box by pressing "OK", define "Top of slope" as the uppermost point by clicking with the mouse, and "Bottom of system" as the lowest point.
Then start the analysis and the following results are acquired:
The slip circle with the highest utilisation factor is located at the top left edge of the selected array. The array must be expanded towards the upper left. Alternatively, a new, appropriately displaced array can be selected.
The slip circle with the highest utilisation factor now lies within the selected array. The stability of the slope is verified. Further arrays may need to be investigated for slopes with numerous layers. In case of uncertainty, the region above the slope face can be plastered with centre-points.
Centre-point array 3 was generated using the menu item "Centre-points/Define in quadrilateral". The following array subdivisions were selected:
The following result is acquired using the selected centre-point array 3:
The result confirms the previous investigations. Defining the search grid using "Horizontal tangents" works almost every time. However, computation may be optimised by using a different definition.
Defining the search grid by selecting the "Start and end radius" is useful for investigating the global stability of a cantilever wall, for example. This allows slip circles passing through the cantilever wall to be excluded from the analysis.
A rational search grid is shown below:
The following analysis result is acquired using this search grid.
