Hi everyone,
I am modeling a staged MSE wall constructed lift-by-lift on a deformable foundation soil in FLAC3D.I am facing a second issue related to the wall–foundation interface. The wall base is intended to interact with the foundation soil (i.e., it is not fixed). However, FLAC3D reports the messages “No faces fell within the range” and “No valid interface nodes in range”, even though the wall base and the foundation top geometrically coincide at . In my model, I create two separate brick zone blocks: one for the foundation soil and another for the MSE wall. I need to define an interface between these two layers such that the MSE wall responds to foundation soil deformation—meaning that when the foundation soil settles, the MSE wall settles accordingly. My current approach is as follows. First, I attach the wall bottom to the foundation top so that they share common faces over the intended contact area. Then, I attempt to create an interface by separating those shared faces over the same spatial range and assign the interface properties (normal and shear stiffness, friction angle, and cohesion). I am using the following syntax:
zone attach by-face range position-z 0.0 position-x 0.0 12.19 position-y 0.0 9.14
zone interface ‘WallFoundation’ create by-face separate range position-z 0.0 position-x 0.0 12.19 position-y 0.0 9.14
zone interface node property stiffness-normal 5.0e7 stiffness-shear 5.0e7 … friction 30 cohesion 8740 range group ‘WallFoundation’
Despite this, the interface is not being created successfully, and FLAC3D reports: “+++ No valid interface nodes in range.” and “+++ No faces fell within the range.”
I would appreciate your guidance on whether this issue could be related to face ownership, zone ordering, geometric tolerance, or the sequence in which the attach and interface-creation steps are applied.
Thank you for your time and support.
Hi Sudipta, as far as I can understand, the attach command is creating problem. If you are using that command, you will have to clear attach- check this out in the create by-face keyword- “clear attach”.
Also, check out these rules of creating interface geometry for additional help with creating an interface elements- Creation of Interface Geometry — FLAC3D 7.0 documentation
Hi @Ankitkumarsuman1
I have a few questions regarding the interface definitions in the model.
- For the interface between FoundationSoil and Soil_L01, I used the following commands:
; Create backfill soil–foundation interface from the panel contact faces
zone interface 'IF_Foundation_Backfill' create by-face range group "Skin=Bottom1"
; Properties
zone interface node property stiffness-normal 9.9e8 stiffness-shear 9.9e8 ...
friction 30 cohesion 0 range interface 'IF_Foundation_Backfill'
; Initialize interface stresses (recommended)
zone interface 'IF_Foundation_Backfill' node initialize-stresses
- I followed the same pattern to create the zone interface between Panel_01 and FoundationSoil, as shown below:
; Create panel–foundation interface from the panel contact faces
zone interface 'IF_Panel_Foundation' create by-face range group "Skin=Panel_Foundation"
; Properties
zone interface node property stiffness-normal 5.0e7 stiffness-shear 5.0e7 ...
friction 20 cohesion 6.6e4 range interface 'IF_Panel_Foundation'
; Initialize
zone interface 'IF_Panel_Foundation' node initialize-stresses
However, FLAC3D reports the following messages:
+++ No valid interface nodes in range
+++ No valid nodes found to assign stresses
Could you please explain the likely reason for this issue?
- Finally, I would like to ask how I can visually or numerically verify from the model that the interfaces have been correctly created between:
Thank you very much for your time and guidance. I truly appreciate your help. It would be great if could check my model script.
Dear @Sudipta, You have to separate the faces first using “zone interface create by-face” command and use “separate” keyword in that so that the faces are separated first and you will be able to create your interfaces on either of the faces. You have to make sure that the face on whoich the interface elements are created has to have greater zone density. Read: Creation of Interface Geometry — FLAC3D 7.0 documentation .
Now, for the different interfaces, the properties will obviously change.
- Identify the stiffer zone adjascent to your interface.
- Set the normal and shear stiffness of the interface elements as per the FLAC Documentation guideline i.e., A good rule-of-thumb is that ks and kn be set to ten times the equivalent stiffness of the stiffest neighboring zone.
- Cohesion and angle of internal friction can be taken from the soil properties by using a penalty function by referring to some of the published literature. Read: Choice of Material Properties — FLAC3D 7.0 documentation
Alternatively, you can perform a direct shear test to assess the interface properties.
Note- All the answers here are according to my knowledge. If anyone feels anything wrong with the explanation, you can correct it in this thread, please. Thank you.
Hi @Ankitkumarsuman1
Here, the foundation soil and the MSE wall are created as two separate bricks, so the two groups of zones are not attached at a common face. That is why I did not use the “separate” keyword when creating the interface.
However, my question is: when I applied the interface between the foundation soil and soil_L01, it worked properly, but when I applied the same approach between the panel and the foundation soil, it did not work. I am unable to understand the reason for this behavior.
Could you kindly check my model script?
If the faces have different dimensions, they are already separated; if they have the same dimensions and all nodes are shared by the two faces, you need to separate them.