Dear Mostafa Abbasinejad,

It seems to be interesting but under geostatic stress getting plastic points may not be possible. Because, geostatic stress in soil is basically due to its own weight and it increases with depth. Also, at any time the stress at any point in soil remains constant unless the soil is loaded with any external forces. If soil is loaded with sufficient load then one can get plastic points.

I think in "Initial Phase (Step 3)", you might have activated applied load, so that's why, you might be getting plastic points.

Thanking You.

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Shivanand

if F=tan(𝜙)/tan(ϴ), your ϴ is 26.6°. ϴ>𝜙. 

You can recalculate with more width and checking failure zone.

Regards

Hadi

how is it possible that you have plastic points in initial phase? in addition, check out the elastic parameters, you may have assigned them wrong

@Shivanand Mahadeo Mali, There is no load on top of the slope, there is just 1 phase for geostatic equilibrium.

@Emad Maleksaeedi, your question is my question too! How is it possible? all parameters are correct

Not sure to have understood the question, but usually it is possible to apply at the very beginning of the calculation a fictitious cohesion, then initialize gravity, then for the further steps aplly the real parameters. This procedure can help to avoid undesired strips of elements in plasticity.

Regards

C.O.

I'm not familiar with PLAXIS, but it looks like the slope angle of about 26.5 degrees is well in excess of the 20 degree soil friction angle.  I wonder whether this is the reason for the behaviour of your model?  You could try increasing the soil friction angle (to at least 26.5 degrees) and see how the model responds.  Good luck, Ian

Haven't worked with plaxis much but this could be reasonable.

When you generate the soil mass, no stresses exist within the soil body. Therefore (Imagine MC failure criteria in your head) small increase in shear stresses could cause your soil element to fail (It has no normal stress acting on it when it is just generated).

There are usually several ways to approach this problem. Some softwares have option to estimate geostatic stress conditions, apply them and then let gravity do its work to reach equilibrium.

One other solution is to let the soil undergo plastic deformations until it reaches equilibrium, no element should be remaining in yield condition at the end of this stage. Then you can reset displacements to zero. This way, your stresses are kept while all the "unrealistic" plastic deformations are taken away as if your soil had never yielded before.

No matter what you do, it is important to make sure your stresses are reasonable (matching what you expect in the field) and the geometry is also what you intended.

Hope this helps!