Hi, I am a newbie in Plaxis 3D. I am setting the model of deep excavation with lateral support.
First, I creat the soil/existing ground by borehole only, and i set some volume to deactivate since the ground surface is not flat. And I creat all excavation volume by "structure: surface with extrude tool", it is not accurate due to the excavated surface with the different gradient in real case. The result generated is reasonably close.
Then, I found that the existing ground surface can be imported in borehole setting. I imported the surface in DXF format and it looks really great!! After that (re-calculation), it fails just in stage 1 (inserting sheet pile wall without any excavation). I dont know whats going on and i found that there are some external water load adding to the sectional face, which does not appear in my first method.
Please help.... Thank you.
Best Regards,
William
Dear Wiliam,
Unfortunately, I do not know the way for triming the soil body.
In your project I see two possible ways:
1. Check the origin surface in DXF, Import settings in PLAXIS and Contour in Project properties window on Model tab.2. Check plate geometry via echo command to get the exact coordinates of plate elements. Another method: delete all structures and check the error only with soil body. If the problem remains, the trouble is in the imported geometry.
Sorry, but it is very difficult to help without origin 3D project.
Dear Rushan,
Thank you for your big help! I found the way out! It really depends on the boundary of the imported DXF surface.
I imported the top soil layer by "structure" and buildup solid/volume, and "connect" to another soil layer, it works and it gives me a clear cut boundary!! Until now it works great. Thank you x 1000!
Dear William,
Great! I am very glad, that your issue has been resolved.You are welcome ;)
The problem you experienced can happen due to a small inaccuracy of the created geometry (usually from import).
Most of the times this inaccuracy is too small to be noticed while checking the model, however, the program will indicate this when applying the default fixities.
By default all lateral (and bottom) boundaries have fixities. The default fixities are applied to the extremes of the model, i.e. Xmin, Ymin, Xmax, Ymax, Zmin, which means that if one of the lateral boundaries, as correctly mentioned by Rushan, is not perfectly vertical, then some part of the geometry will not have any fixities as the whole lateral boundary is not the extreme of that model, but probably some part of the geometry.
As a result, when fixities are not applied and a water level is present, external water loads are applied to the model, which are not supposed to be generated at all.
In that case, you need to inspect the part of the geometry that is missing the fixities and show external water loads and go back to Input and try to fix it.
One way is to check the importance file and fix the issue before importing it to PLAXIS.
Another way is to force an intersection between a vertical surface you can quickly create in Input and the soil volumes. The intersect command can be executed in the command line as follows:
intersect BoreholeVolume_1 Polygon_2 # for two objects
intersect BoreholeVolume_1 BoreholeVolume_2 BoreholeVolume_3 Polygon_1 # for multiple objects
As a result, the manual intersection will create new objects which will be editable in Structures mode. Then, you can delete the parts that seem to "stick out" to fix the geometry. Typically you can check the command response to identify all created objects from intersections.
If you encounter any similar issues you cannot fix, please submit a service request.
Then, one of our support engineers can help you in detail: https://apps.bentley.com/srmanager/ProductSupport
Dear Stefanos,
Great thanks for the information about intersect BoreholeVolume_1 ... Polygon_2 command.I did not think about this simple way.