# Soil-pipe interaction analysis

**URL:** <https://calculix.discourse.group/t/soil-pipe-interaction-analysis/4078>\
**Category:** Model setup\
**Created:** [July 29, 2026, 7:57pm UTC](https://calculix.discourse.group/t/soil-pipe-interaction-analysis/4078 "2026-07-29T19:57:44Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Juseche](https://avatars.discourse-cdn.com/v4/letter/j/258eb7/32.png) [@Juseche](https://calculix.discourse.group/u/Juseche)\
**Post date:** [July 29, 2026, 7:57pm UTC](https://calculix.discourse.group/t/soil-pipe-interaction-analysis/4078/1 "2026-07-29T19:57:44Z")

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Hi!

This is a model for soil-pipe interaction analysis. It is experiencing convergence issues; what is the best way to model this problem?

The link to the INP file is as follows:

Thanks in advance.

> **[modelo\_suelo\_tuberia\_20m\_contacto\_corregido.inp](https://drive.google.com/file/d/1G-KNhsVnCL-6NqALKE4XSEhxtYU8VYN9/view?usp=drive_link)**
>
> Google Drive file.

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**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\
**Post date:** [July 30, 2026, 10:21am UTC](https://calculix.discourse.group/t/soil-pipe-interaction-analysis/4078/2 "2026-07-30T10:21:00Z")

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Check if it works without friction. If not, replace contact with tie constraint and see if the results make sense. If it still doesn’t converge, you may need to remove Nlgeom and plasticity as well for debugging.

Also, try with the pipe modeled using solid elements.

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<div class="post-metadata">

**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\
**Post date:** [July 30, 2026, 10:26am UTC](https://calculix.discourse.group/t/soil-pipe-interaction-analysis/4078/3 "2026-07-30T10:26:42Z")

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> [@Calc\_em](#):
>
> Also, try with the pipe modeled using solid elements.

Or at least don’t fix all rotations for the pipe - shells in CalculiX may fail to converge if their drilling DOF is constrained.