When the model width is determined by the soil layers and these soil layers are generated by boreholes, the horizontal model dimensions are defined by the Model Contour in the Project properties (available via the File Menu):
Figure 1. Model contour in PLAXIS 2D AE’s Project Properties
When changing the values for the horizontal dimensions, the soil layer generation will take these horizontal coordinates as limits. For PLAXIS 2D this will be xmin and xmax, and for PLAXIS 3D this will be xmin, xmax, ymin and ymax.
If the soil layers in the program are defined by not using the borehole, e.g. Polygons in PLAXIS 2D and Volumes in PLAXIS 3D, this model contour does not define the overall model width. To change the model width, you will need to modify these Polygons (2D) and Volumes (3D).
To do this in PLAXIS 2D (2D AE.02, and later):
Figure 2. Highlighted Helper points of a Polygon (right) and HelperPoints in the Selection explorer (left)
In PLAXIS 3D, such a volume cannot be modified. A new volume needs to be created in PLAXIS 3D in order to change the model’s width based on volumes.
One approach to extend the width of the 3D model, is by adding the extension as separate volumes:
This needs to be repeated for each volume that form the boundary.
For reducing the size of the model, .i.e. removing part of the volumes:
Repeat the steps above for each model boundary.