In cases where you have a circular tunnel designed (i.e. one segment of 360 degrees) and at least an inside (positive) interface is assigned to the tunnel, the model will not be able to be meshed in PLAXIS 2D AE due to this inside interface on a full circle.
Figure 1. Tunnel shape with inside interface
The program will give the following error: Meshing failed with the following error: Mesh output file not found
This issue is now solved since PLAXIS 2D 2015.00: now a circular tunnel will by default consist of two segments in stead of just one. This prevents this issue to occur. Note: for full circular shapes the above mentioned problem may still occur.
In older versions, this issue can be solved if instead of one segment the circular tunnel is designed with two segments of 180 degrees each:
Now the model will have no problem generating the mesh.
Figure 2. Workaround step 1: set the shape to Free
Figure 3. Workaround step 2 and 3: add a segment of 180 degrees and symmetrically close the tunnel
Figure 4. Workaround step 4: Add Properties to the segments