Soil Excavation

[fo2sh]

Hi Dear All,
I am using ABAQUS to investigate the soil stressess around a buried pipe. I managed to simulate the geostatic condition successfully.
After Running this model, I have to excavate a trench in the soil profile. I went over the manual and I knew about the Model Change, Remove command. It works fine and reasonable results as long as I assign my region of excavation as Partioned sections of the original soil.
I tried to redo the model where I assigned each section to be excavated as a separate part and I assigned some contact interaction between The two soils. At this stage I would like to know what type of contact I have to select for the tangential and normal behavior when I deal with two soil that are self contact originally.
The second challenging phase of my simulation is the backfilling process. I went over the different posted replies and I came with the idea to split my steps into two separate parts one for the geostatic and excavation then I Transferr the results to Another ABAQUS/Standard model to apply the different new parts shapes and Material properties. I am still lost in doing this because I am completely confused how to import the results successfully in the new model to restart my analysis which the backfilling process.
thanks for anyone who can clarify me some tips or ideas.
best regards
Sherif

 

[geo2006]

Hi,

just 2 ideas. For the contact issue, are you really interested in studying the contact behavior? If you only are trying to transmit forces between parts, using constraints instead of contacts may be easier.

To the second part: I think you can model the process activating and deactivating parts and changing its properties, all in 1 analysis.

Just my 2$.

 

[barney75]

Hi Sherif,
Few months ago I've tried some analyses with buried pipeline but my poor geothecnical background coupled with Abaqus did not allow me to go very far from the starting point. Basically I need some advice as the element and the material model to be used for modelling pipe interacting with a soft clayey soil for instance. I really appreciate any suggestion/advice you could give me.

Thanks in advance.
Barney75

 

[fo2sh]

Hi Barney75,
I think since you are dealing with clay you may use cam clay model for your soil properties. Pipe soil contact I am still at the stage of figuring how to define this in accurate way and in other extent to be time economic from a discussion with one colleague adding contact properties in the model will make run very slow and it is very time cosuming to get the results. If you are interested in rough contact I suggest you merge/cut tool to assign bonded contact between the pipe and the soil.
The pipe should be a rigid body so if you define it a beam element you can assign the pipe soil element available in the ABAQUS library.
I wish you all the best and I would like to share your trial and mistakes further so that we can learn more.
Yours
sherif

 

[barney75]

Hi Sherif,
thanks for your advices. Actually I've used the so-pi implented in Abaqus in my model for investigating several issues but the problem is that it's time for me -)) to move to a model based on shell element pipe interacting with surronding soil (clay or sand meshed as brick element?). Since I'm not a civil engineer everything is a litlle bit more complicated. I hope we may share some other tip&triks on this matter.

Thanks a lot

See u