Weird displacements contours at initial state

FLAC3D
1

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
disp_cont3800×2190 469 KB

vel_cont
vel_cont3800×2190 478 KB

2

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

3

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

4

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

5

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

6

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

7

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?

8

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)
As you can see, the principal stresses are assigned via the function “iniprin” which can be found in the “FishTask” file of this example.

9

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

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
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