pipe-soil interaction element in Abaqus/CAE

[SIAVASH54]

Hello all,

I am modeling a buried pipeline. Can you please help me with modeling pipe-soil interaction elements? I don't know how to do this in Abaqus/CAE.

Thanks
Sia

 

[FEA way]

Check the examples in Abaqus documentation. There are some in the Verification Guide but also in the Example Problems Guide ("Analysis of a pipeline buried in soil"). I would especially recommend the latter since it involves a specific engineering problem, not just abstract test.

 

[SIAVASH54]

Thanks for your reply "FEA way".
I checked the example and it is sharing some input files ".inp" for the models, that I don't know how to use them on Abaqus CAE 2020. I cannot import this type of files(.inp) in Abaqus 2020. I cannot find any menu to create the pipe-soil interaction elements. And this version seems to not have command line support, so I cannot use commands to create the elements. I appreciate your help.

 

[NRP99]

One time activity for example problem file download- Go to directory-C:\Win64App\ABAQUS20xx\SIMULIA\CAE\20xx\win_b64\SMA\samples\job_archive. Extract the samples.zip file to another folder. Open new database in Abaqus. Import the required example problem input file in model from the unzipped folder.

You can import *.inp files by going to file menu=>import=>select .inp format from file filter and import the required inp file in the CAE.

You need to insert specific commands related to pipe-soil interaction elements to specific element set in inp file rather than command line or GUI menu item.

 

[FEA way]

Usually those exemplary input files from the documentation are submitted from the command line (abaqus job=input_file_name) and GUI is used only for postprocessing. But you can also import the input file as a model to Abaqus/CAE and explore its contents there. Just keep in mind that some keywords are not supported by Abaqus/CAE (and thus won’t be imported) and that mesh will be available in so called orphan form - without underlying geometry so no option for easy refinement.

 

[SIAVASH54]

Thanks for your help NRP99 and FEAway. I could import the .inp files by importing "part".
I just noticed that pipe-soil interaction elements can only be used with "beam" pipes, and not "shell" pipes. Am I right? And as Abaqus recommendation, when there is large amount of bending moments(like cross-country pipelines with long pipes and sharp bends), pipes and bends must be modeled as "shell" parts. So, in this case, what is the best option to model the pipe-soil interaction. Specifically, how to model soil spring stiffness? Should I model the soil as a deformable soil extrude or sweep and put the pipe system inside it and use "interaction" to simulate the soil spring values in three(or four) directions?

 

[FEA way]

Importing inp files as parts is somewhat different since you won’t get all the necessary model features.

Pipe-soil interaction elements are indeed available only for use with 1D (beam, pipe or elbow) representations of pipelines. If you want to use shells instead, you will have to model the underlying soil either with a spring foundation feature or discretely. Proper material model (Abaqus offers several materials meant specifically for geotechnical applications) and contact interaction will let you model this accurately.

 

[NRP99]

"Subsea Pipeline Design, Analysis, and Installation" by Qiang Bai and Yong Bai may contain guideline you need.