User-Defined Slip Surface Overview

The Add User-Defined Surface option allows you to define any general slip surface shape as a User-Defined Slip Surface.

This option is only enabled if the Surface Generation Method in the Slip Surface Options dialog is set to User-Defined Surfaces.

To add a user-defined slip surface:

1. Select the Slip Surfaces workflow tab.
2. Make sure the Surface Generation Method = User Defined Surfaces in the Slip Surface Options dialog.
3. Select Add User-Defined Surface from the toolbar or the Surfaces menu.
4. You will see the Add User Defined Slip Surface dialog. In the dialog, select an existing surface, enter a name and select OK.
5. The User Defined Slip Surface will be added to the model.

You can add any number of user-defined slip surfaces. To add additional surfaces repeat steps 3 to 5.

A User-Defined Slip Surface is a spherical, ellipsoidal or general slip surface created with one of the Add User-Defined Surface options:

• Add User-Defined Sphere/Ellipse Surface
• Add User-Defined Surface
• Add User-Defined Surface from Global Minimum

These options are only enabled if the Surface Generation Method in the Slip Surface Options dialog is set to User-Defined Surfaces.

Search Methods and User-Defined Surfaces

When you add a user-defined slip surface:

• You can apply the Surface Altering Optimization option to User Defined slip surfaces. In this case, the User Defined Surface will be converted to a spline surface and used as the starting location for the Surface Altering Optimization to search for lower safety factor surfaces.
• You can use the External Geometry Composite Surface option with User-Defined slip surfaces.
• You CANNOT use the primary Search Methods (e.g. Grid Search, Cuckoo Search, Particle Swarm) in conjunction with User-Defined Slip Surfaces. The two options are exclusive. If you need to analyze user-defined slip surfaces and search for critical surfaces using the primary Search Methods, then you will have to carry out the analyses separately.