xtrata
Civil/Environmental
- Mar 12, 2012
- 5
I have a 50mx25m section of Clay analysed in Plane Strain.
It's density is
*Density
1977., (kg/m3)
So therefore I specify the initial geostatic stress condition as
*INITIAL CONDITIONS, TYPE=STRESS, GEOSTATIC
LCESET,0,25,-485000,0,2
As 25x1977x9.81=484859 N/m2
Gravity is specified as
*Dload
_PickedSet188, GRAV, 9.81, 0., -1.
Pickeset188 is the mesh region
But when I run the Geostatic analysis I get displacements of 283 mm which is a lot. I have found an old thread that says
"The displacements will only be zero if you apply a set of loads that exactly equilbreate your initial state
of stress.
You can solve the problem by first running a single step with the initial conditions applied and boundary
conditions on every dof. The reaction forces will the be forces required to maintain the state of stress. Write the reactions forces to the results file or odb file. Post process the results file or odb file so you can use the reactions forces as concentrated loads in your actual analysis. In you actual analysis apply these forces as concentrated loads in your geostatic step. Leave the concentrated forces in the analysis for subsequent steps." (
But surely there must be a simpler method
It's density is
*Density
1977., (kg/m3)
So therefore I specify the initial geostatic stress condition as
*INITIAL CONDITIONS, TYPE=STRESS, GEOSTATIC
LCESET,0,25,-485000,0,2
As 25x1977x9.81=484859 N/m2
Gravity is specified as
*Dload
_PickedSet188, GRAV, 9.81, 0., -1.
Pickeset188 is the mesh region
But when I run the Geostatic analysis I get displacements of 283 mm which is a lot. I have found an old thread that says
"The displacements will only be zero if you apply a set of loads that exactly equilbreate your initial state
of stress.
You can solve the problem by first running a single step with the initial conditions applied and boundary
conditions on every dof. The reaction forces will the be forces required to maintain the state of stress. Write the reactions forces to the results file or odb file. Post process the results file or odb file so you can use the reactions forces as concentrated loads in your actual analysis. In you actual analysis apply these forces as concentrated loads in your geostatic step. Leave the concentrated forces in the analysis for subsequent steps." (
But surely there must be a simpler method