Global Minimum Slip Surface

The Global Minimum Slip Surface is the 3D slip surface with the LOWEST factor of safety, for a given analysis method, of all slip surfaces analyzed.

The Global Minimum Slip Surface and Factor of Safety are automatically displayed when you view analysis results.

• You can plot data contours on the Global Minimum Slip Surface with the Show Contours option.
• You can show or hide the display of the Global Minimum Slip Surface using the Visibility settings in the sidebar.

Factor of Safety

The factor of safety for the Global Minimum is displayed in two locations:

• in the Analysis Method selection box
• at the top of the Perspective view of the model

Analysis Method

By default, when Results are viewed, the Global Minimum slip surface for the Bishop analysis method will be displayed (if a Bishop analysis was one of the analysis methods used).

To view the Global Minimum surface and safety factor for other analysis methods (e.g. Janbu, Spencer, GLE), use the mouse to select a method from the drop-list in the workflow bar.

It is important to realize that the Global Minimum surface will NOT NECESSARILY BE THE SAME SURFACE, FOR DIFFERENT ANALYSIS METHODS. In general, each analysis method may find a different Global Minimum surface and safety factor.

Finding the True Global Minimum

The term "Global Minimum" should be used with caution. The Global Minimum surfaces displayed after an analysis, are only as good as your search techniques, and may not necessarily be the lowest possible safety factor surfaces for a given model. Depending on your search methods and parameters, surfaces with lower safety factors may exist.