Dear all,
I am trying to model a simple multiple layer rehabilitated embankment in Flac3D and I am new to this software. In my model, I use modified cam clay model for two consecutive layers, strain hardening/softening model for the soil replacement material, and linear elastic model for the overlaying pavement. Now, any time I ran the project, I faced two errors:
1- *** Cam-clay: Bulk modulus bound must be increased for stability.
once I increase the Bulk modulus, I encounter another error:
2- *** Cam-clay: Yield envelope cannot be reached
I will appreciate if you please let me know the possible reasons for these errors.
Thank you
What is the bulk modulus you have taken?
please send me the entire code.
be carefull with the initial stress field, it must be consistent with the model parameters
Ana,
you are quite right. Actually I used the same parameters which were applied for the Plaxis SS (soft soil) model. I also think that the main reason can be due to the soil parameters. But even by changing them, I couldn't have passed the initial condition step.
Hello Bulent Kocak. Yes. I could have resolved that issue. Actually I made a mistake during the soil's parameter correlations. Please pay attention to the Ana Vieria's recommendation.
Hello Ali Shafikhani, I am also getting same error. May you please help me to resolve these problems.
Thank you
Hi all, I am also getting same errors even I defined the initial conditions and use absolute before mean pressure. anyone could help me
Dear Mouhieddine and Kumar,
If you use cam-clay model, please make sure that you need to initialize stresses and pore pressures for cam clay model prior to loading and running the code. Simply, you need to add this commands in your model before the loading:
;---"Initializing Cam clay mean effective stress"----
def camclay_ini_p
local nccz = 0
local mean_p = 0
local p_z = zone_head
loop while p_z # null
if z_model (p_z) = 'cam-clay' then
nccz = nccz + 1
mean_p = -(z_sxx(p_z) + z_syy(p_z) + z_szz(p_z))/3.0 - z_pp(p_z)
z_prop(p_z,'cam_cp') = mean_p
end_if
p_z = z_next(p_z)
endloop
local oo=out(' '+string(nccz)+' zones with camclay')
end
@camclay_ini_p
-------------------------------------------------------------------------------------
Also, you need to precisely correlate cam clay parameters by considering the stress boundary conditions at the bottom of the layer in which, you try to define with cam clay constitutive model (specially the bulk_bound parameter).
Please feel free to ask questions.
Dear Ali,
Thank you for your kind response.
I used this code but still i was getting same problem. Again, I am going to try this.
You are welcome Kumar,
So, the problem can be due to a mistake during the correlation of cam clay soil parameters especially the bulk modulus. You need to consider the boundary stresses at the bottom of the layer to correlate the bulk modulus. Otherwise, you will face the same problem again.
Best regards
Dear ali ,
I'm modeling a triaxial test ( cylindrical model) in flac 3d 6 using cam- clay model.
I tried the model from model cyle 100 to model cycle 90000 . Till the trail with model cycle 80000 the code had no errors. But when when I increase the cycle no to 90000 it showed the same error *** cam-clay: Yield envelope cannot be reached.
I appreciate any help regarding this error.
Thank you.
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