Servo mechanism for multiple walls

Hey everyone,

this question is somehow related to this topic (History for facets - #4 by dblanksma). I have modeled the pile now creating different walls. I have assigned all the walls to the group “pile”. Now, I want to apply a servo-mechanism on the whole pile to conduct a load test. However, although the servo-mechanism is applied on all walls, it is not applied on the whole pile as an one unit. Thus, the walls move not in-sync (photo attached below) Does anybody know how to handle this issue?
Thanks in advance!


Hi Nick,
we are looking into this.
You will hear back from us soon.

Hello Nick,

I am not sure why the walls are moving apart. My guess is you may gave made separate walls and they each have a different servo condition. Could you share how you created your walls?

Dear dblanksma,
I have seen the same issue in one of my simulations.

I have tried to sum it up in one simple example (I have mocked up the footing example from the manual for that).

I have created a group of walls that would all move in line when beeing pushed down into an assembly of balls using the “wall attribute velocity-y” command but wouldnt do so when a servo mechanism is beeing used applying a load in the same direction.

Maybe there is some basic thing that Nick and I are missing here?

Thank you very much!


Bottom_Wall_Stress.dat (2.0 KB)
Wall_Displacement.dat (9.1 KB)
footing_2D.dat (4.9 KB)

Dear Derrick, dear Nick,
is this issue solved already?


I have not checked @Mussie data files. If @nibel22 finds your solution satisfactory I think we can call it resolved.

Dear Derrick,
this seems to be a missunderstanding.

As I am seeing the same problem within my simulations right now, I have just provided files that display the same issue of separately moving walls when using a servo mechanism (an illustrative example similar to the case that Nick is explaining) - I havent provided a solution.


Hey @Mussie, sorry for the miscommunication. I assumed you had resolved this issue. I will look into it.

– Derrick

Thank you very much Derrick!


Hello @Mussie,

I found that if you add the one-wall keyword to the foundation walls they will behave as a single wall and not separate when loading with servo conditions. I am not sure if you have tried this, but it may be worth trying.

– Derrick

Thank you Derrick! The one-wall keyword worked fine for me.

Sorry for the late response - I was offline for some time.