Note that since the release of PLAXIS 3D AE.00 it is recommended to use the 3D Tunnel designer to create curved tunnels instead of the approach discussed here.

Starting from PLAXIS 3D2012 it is possible to extrude a polycurve along a curved path, as defined by another polycurve. This can be used to generate for example a curved tunnel or an embankment construction along a predefined path. This extrusion can be achieved either via a command and via the graphical user interface using the mouse.

 

User interface

For this example we will create a curved circular tunnel shape by using the mouse. We start with a polycurve, Polycurve_1, that forms the circular cross section of the tunnel, and the path of the curved tunnel as Polycurve_2.

Now we will first select the circular tunnel shape (Polycurve_1), and then we will select the path (Polycurve_2). The selection order is important, since this will determine which polycurve will be extruded over which path (the second selected polycurve).
After the selection, right click on one of the polycurves, and from the popup menu choose Extrude. After the extrusion process, we obtained the desired curved tunnel shape:

Now, one can assign e.g. plates and interfaces to this generated surface.

Command

The command to extrude a polycurve along another polycurve is:
extrude polycurve(shape) polycurve(path)
The first polycurve defines the shape you want to extrude, the second polycurve is the definition of the path.

In the example above, as we defined the circular tunnel shape as Polycurve_1 and the path as Polycurve_2, the command would look like:
extrude Polycurve_1 Polycurve_2