# Weird displacements contours at initial state

**URL:** <https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096>\
**Category:** FLAC3D\
**Created:** [July 27, 2023, 1:35pm UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096 "2023-07-27T13:35:35Z")\
**Posts on this page:** 9\
**Page:** 1

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**Author:** ![Carlos\_Mora](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@Carlos\_Mora](https://forum.itascainternational.com/u/Carlos_Mora)\
**Post date:** [July 27, 2023, 1:35pm UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096/1 "2023-07-27T13:35:35Z")

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Hello! I get to equilibrium next model with no problem but displacement and velocity contours do not seem like equilibrium is reached. I cycled the model 10000 steps more but any change. In elastic cmodel contours are horizontal but when change to Plastic-Hardening this situation arise. I´d appreciate if you can help me, thank you in advance.

 ![disp_cont](https://canada1.discourse-cdn.com/flex031/uploads/itasca/original/1X/621356247c18aa2b640d5ce9f172cce9f36581d0.png)  
 ![vel_cont](https://canada1.discourse-cdn.com/flex031/uploads/itasca/original/1X/2ee2a92a0627f315d18d355a91db961b42dd3513.png)

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**Author:** ![msepu](https://avatars.discourse-cdn.com/v4/letter/m/b9e5f3/32.png) [@msepu](https://forum.itascainternational.com/u/msepu)\
**Post date:** [July 27, 2023, 2:16pm UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096/2 "2023-07-27T14:16:58Z")

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Are the boundary conditions ok? i mean… roller at elastic and fixed in plastic?

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**Author:** ![Huy](https://avatars.discourse-cdn.com/v4/letter/h/c5a1d2/32.png) [@Huy](https://forum.itascainternational.com/u/Huy)\
**Post date:** [July 27, 2023, 2:28pm UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096/3 "2023-07-27T14:28:25Z")

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For the PH model, you need to set the initial principal stresses (stress-1-effective …) .

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**Author:** ![Carlos\_Mora](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@Carlos\_Mora](https://forum.itascainternational.com/u/Carlos_Mora)\
**Post date:** [July 31, 2023, 9:33am UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096/4 "2023-07-31T09:33:56Z")

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Thanks Matias, yes boundary conditions were ok, the problem was I did not set the initial principal stresses for the PH model.

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**Author:** ![Carlos\_Mora](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@Carlos\_Mora](https://forum.itascainternational.com/u/Carlos_Mora)\
**Post date:** [July 31, 2023, 9:35am UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096/5 "2023-07-31T09:35:44Z")

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Thanks Huy, I set the initial principal stresses for the PH model and now contours plots are ok!

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**Author:** ![MiguelN](https://avatars.discourse-cdn.com/v4/letter/m/6f9a4e/32.png) [@MiguelN](https://forum.itascainternational.com/u/MiguelN)\
**Post date:** [August 1, 2023, 5:28pm UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096/6 "2023-08-01T17:28:03Z")

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Carlos, I solve the model as elastic to reach the in situ stresses, and then rescue the prinicipal stresses to use for the plastic hardening by fish. Cheers

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**Author:** ![Sullivan](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Sullivan](https://forum.itascainternational.com/u/Sullivan)\
**Post date:** [August 25, 2023, 8:08am UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096/7 "2023-08-25T08:08:46Z")

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hello Huy,  
The initial principal stresses in PH model puzzle me a lot.  
Is it possible to solve the problem inwhich the soil is M-C material with “model solve elastic”, and then change the M-C to PH without assigning the intial principal stresses?

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**Author:** ![Huy](https://avatars.discourse-cdn.com/v4/letter/h/c5a1d2/32.png) [@Huy](https://forum.itascainternational.com/u/Huy)\
**Post date:** [August 25, 2023, 8:40am UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096/8 "2023-08-25T08:40:14Z")

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You need to set the initial principal stresses for PH model because it’s a stress-dependent model.  
You can have a look on the example below in the FLAC3D documentation.  
[Reinforced Tunnel Excavation (FLAC3D) — Itasca Software 9.0 documentation (itascacg.com)](https://docs.itascacg.com/itasca900/flac3d/zonesel/test3d/ExampleApplications/ReinforcedTunnelExcavation/reinforcedtunnelexcavation.html?highlight=ph)  
As you can see, the principal stresses are assigned via the function “iniprin” which can be found in the “FishTask” file of this example.

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<div class="post-metadata">

**Author:** ![Sullivan](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Sullivan](https://forum.itascainternational.com/u/Sullivan)\
**Post date:** [August 25, 2023, 10:16am UTC](https://forum.itascainternational.com/t/weird-displacements-contours-at-initial-state/1096/9 "2023-08-25T10:16:06Z")

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than means, after I set the model to PH, we must assign the principal stress from the m-c model just like below?

```auto
fish define iniprin
    loop foreach z zone.list
        if zone.model(z) == 'plastic-hardening' then
            zone.prop(z,'stress-1-effective') = zone.stress.min(z)
            zone.prop(z,'stress-2-effective') = zone.stress.int(z)
            zone.prop(z,'stress-3-effective') = zone.stress.max(z)
        endif
    endloop
end

```