[Geoqus] Far Field Stresses,Thank Wouter and Jose

[Manooch Salehabadi]

Dear Wouter:

 

Hi,

Really thank you for your kind and attention, I will follow your
comments for my modelling, also I should say thank you to Jose For her
comments as well.

 

Regards

 

Manooch 

 

 

________________________________

From:
geoqus-bounces+manooch.salehabadi=pet.hw.ac.uk at lists.ruhr-uni-bochum.de
[mailto:geoqus-bounces+manooch.salehabadi=pet.hw.ac.uk at lists.ruhr-uni-bo
chum.de] On Behalf Of Wouter van der Zee
Sent: 27 March 2007 22:53
To: 'Geoscientific Abaqus User Group'
Subject: Re: [Geoqus] Far Field Stresses

 

Manooch,

 

to incorporate the field stresses, I would use:

 

*initial conditions, type=stress

and

*initial conditions, type=pore pressure 

and 

*initial conditions, type=ratio

 

To keep the stresses in your model, either make your mesh large enough
and hold the outside boundary in 1,2 direction, or use the infinite
element as Jose pointed out. Be aware that you should provide effective
stresses, not total stresses.

 

Please note that from your part of the input file it looks like you want
to calculate time dependent pore pressure (although you call your step
"equilibrium step"). If you want to calculate the equilibrium only them
remove "consolidation, end=PERIOD", it probably makes convergence also
more likely, and you don't have to worry about the permeability of your
material. As soon as you understand your model, you can switch to
time-dependent modeling, and start playing with the permeability (and
unit system).

 

Good luck,

 

Wouter

 

________________________________

From: geoqus-bounces+wvanderzee=geomi.com at lists.ruhr-uni-bochum.de
[mailto:geoqus-bounces+wvanderzee=geomi.com at lists.ruhr-uni-bochum.de] On
Behalf Of Manooch Salehabadi
Sent: Tuesday, March 27, 2007 3:52 PM
To: Geoscientific Abaqus User Group
Subject: Far Field Stresses

 

Dear All,

hi and sorry for this simple question , i am just a beginner with
ABAQUS.

i am trying to model a bore hole in mohr coulomb media (rock) with plain
strain element CPE8RP, but i do not know how 

to include far field stress in the model?

i have used simple hollow cylindrical model with loading as following to
simulate far field stresses:

 

*Step, name="Equilibrium Step", nlgeom=YES

*Soils, consolidation, end=PERIOD, utol=10., creep=none

100., 14400., 0.144, 14400., 

 

** LOADS

** 

** Name: Far Field Stress Type: Pressure

*Dsload

"Outer Boundary Surface", P, 24.

** Name: Mud Pressure-surface Type: Pressure

*Dsload

"wellbore Face", P, 20.

** 

unit is in MPa , i considered 24 Mpa as far field stress and 20 Mpa as
borehole pressure ,also i have considered

18 Mpa as an initial pore pressure , but i didnot get reasonable
results.!

i will be much appreciated for any comments.

Regards

Manooch 

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