Initial stress state for an irregular surface topography

FLAC3D
1

Hello,

When dealing with irregular surface topography to reach equilibrium, Itasca recommends:

There is no simple way to calculate initial stresses that are nearer equilibrium for this case. There are a number of different possible methods one could use to help, however:

  1. Use multiple zone initialize-stresses commands at different elevations and regions, with different ratio values.
  2. Solve the model elastically.
  3. Reset displacement after reaching initial equilibrium (this is generally good practice in any case).
  4. Allow plastic flow to occur, thus removing stress concentrations, and then re-assign constitutive models to reset state variables.

When trying to perform step 4 (basically using “zone cmodel assign” and “zone property …” commands), the zone state (e.g., shear-n shear-p) does not reset. Am I misunderstanding what step 4 should do?

Script.zip (615.0 KB)

2

Just use this command:
zone initialize state 0

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3

It works. Thanks Zhao :+1:

4

Another method to try to initialize the model to the desired stresses is to use, in the first phase, ad hoc Poisson’s coefficient value(s) using a linear elastic material, for which the following equation holds:
image
After the initialization, you can switch the constitutive model to the most appropriate for your purposes and run again the model: the only changes should be those caused by the state of stress out of the yielding surface (some plastic points could appear).

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