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Version
6.4
Titrate:
SSNV165 - Triaxial Essai not drained with law CAM_CLAY
Date:
03/06/03
Author (S):
G. DEBRUYNE, J. EL GHARIB Key
:
V6.04.165-A Page:
1/6
Organization (S): EDF-R & D/AMA
Handbook of Validation
V6.04 booklet: Nonlinear statics of the voluminal structures
Document: V6.04.165
SSNV165 - Triaxial Essai not drained with the law
CAM_CLAY
Summary:
This test makes it possible to validate the mechanical law elastoplastic Cam_Clay specific to the grounds normally
consolidated. This law integrates an elastoplastic hydrostatic mechanism (of which the elastic part is
non-linear and the threshold of flow corresponds to the pressure of consolidation) coupled to a mechanism
deviatoric elastoplastic the elastic part is linear. The behavior is hardening or
softening according to the combination of the two mechanisms.
This test carried out in hydro-mechanical coupling includes/understands two ways of loading:
1) a hydrostatic way of compression in condition drained until the pressure of consolidation,
2) a way not-drained by maintaining the pressures lateral confining on the sample and by imposing one
vertical displacement of compression which induces a triaxial state of stresses.
Modeling is carried out in 3D.
Handbook of Validation
V6.04 booklet: Nonlinear statics of the voluminal structures
HT-66/03/008/A
Code_Aster ®
Version
6.4
Titrate:
SSNV165 - Triaxial Essai not drained with law CAM_CLAY
Date:
03/06/03
Author (S):
G. DEBRUYNE, J. EL GHARIB Key
:
V6.04.165-A Page:
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1
Problem of reference
1.1 Geometry
Z
E
H
y
X
L
height: H = 1m
width: L = 1 m
thickness: E = 1 m
1.2
Properties of material
E = 22.4E6 Pa
= 0.3
= 1.E - 5
Parameters specific to CAM_CLAY:
PORO = 0.14, = 0.25, = 0.05, M = 0.9, CLOSE _ CRIT =.
3e5 Pa, Pa = 1.E5 Pa
1.3
Boundary conditions and loadings
The first way of loading is carried out with a state of hydrostatic stresses:
= = = P. One makes a first elastic design to P = Pa (to establish an initial state).
xx
yy
zz
One increases then P to P
= P
=.
6e5Pa = 2P by using Cam_Clay,
sup
ion
consolidat
Cr
pressure of water is null
1
PRE = 0 (drained condition). For the second way, one maintains
pressure P on the side faces and one imposes then a vertical displacement imposed in
compression to model a triaxial compression test, calculation is now not drained, which corresponds to
a hydrostatic flow no one on all the faces.
1.4 Conditions
initial
In CAM_CLAY, the elastic law requires a hydrostatic constraint strictly higher than zero with
the initial state (deformation being null).
To initialize this constraint, one chose to carry out at the beginning a purely elastic calculation in
making evolve/move pressure of 0. with 1.E5 Pa. One extracts from this calculation only the field of
constraints at the points of gauss. This stress field resulting from the elastic design is considered
like the initial state of the hydrostatic constraint necessary to the law Cam_Clay of following calculation.
Handbook of Validation
V6.04 booklet: Nonlinear statics of the voluminal structures
HT-66/03/008/A
Code_Aster ®
Version
6.4
Titrate:
SSNV165 - Triaxial Essai not drained with law CAM_CLAY
Date:
03/06/03
Author (S):
G. DEBRUYNE, J. EL GHARIB Key
:
V6.04.165-A Page:
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2
Reference solution
An exact solution exists as much as the loading is hydrostatic (cf SSNV160). For the second
triaxial way, an analytical solution is not obvious to find. In the same way, one does not have
data and of triaxial experimental test results allowing to compare with calculations.
This test is a test of not-regression.
Handbook of Validation
V6.04 booklet: Nonlinear statics of the voluminal structures
HT-66/03/008/A
Code_Aster ®
Version
6.4
Titrate:
SSNV165 - Triaxial Essai not drained with law CAM_CLAY
Date:
03/06/03
Author (S):
G. DEBRUYNE, J. EL GHARIB Key
:
V6.04.165-A Page:
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3 Modeling
With
3.1
Characteristics of modeling
Modeling 3D
Z
NO3
NO5
NO8
NO2
NO7
y
NO1
NO4
NO6
NO12
NO10
NO9
NO11
X
NO15
NO17
NO20
NO14
NO19
NO13
NO18
NO16
3.2
Characteristics of the grid
A number of nodes:
20
A number of meshs:
1 of type HEXA 20
6 of type QUAD 8
The following meshs are defined:
DROITE
NO3 NO5 NO8 NO10 NO12 NO15 NO17 NO20
GAUCHE
NO1 NO4 NO6 NO9 NO11 NO13 NO16 NO18
DEVANT
NO6 NO7 NO8 NO11 NO12 NO18 NO19 NO20
DERRIERE
NO1 NO2 NO3 NO9 NO10 NO13 NO14 NO15
BAS
NO13 NO14 NO15 NO16 NO17 NO18 NO19 NO20
HAUT
NO1 NO2 NO3 NO4 NO5 NO6 NO7 NO8
To represent the 1/8th structure, the boundary conditions in displacement imposed are:
On face BAS: DZ = 0
On face GAUCHE: DY = 0
On face DERRIERE: DX = 0
The loading is consisted of the same pressure divided into compression on the 3 meshs: `HAUT,
“DROITE” and “DEVANT” to simulate a hydrostatic test with
1
PRE = 0 in drained. Then,
pressure distributed is maintained constant on side faces “DROITE” and “DEVANT”, one
displacement DZ is imposed on variable face “HAUT” with time in not drained.
Handbook of Validation
V6.04 booklet: Nonlinear statics of the voluminal structures
HT-66/03/008/A
Code_Aster ®
Version
6.4
Titrate:
SSNV165 - Triaxial Essai not drained with law CAM_CLAY
Date:
03/06/03
Author (S):
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:
V6.04.165-A Page:
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3.3 Functionalities
tested
Commands
DEFI_MATERIAU CAM_CLAY
STAT_NON_LINE COMP_INCR
RELATION= `KIT_HM'
`RELATION_KIT'=
“CAM_CLAY”
“LIQU_SATU”
“HYDR_UTIL”
NEWTON
STAMP = TANGENT
3.4
Sizes tested and results
The components, and of the constraint are tested at moments 3., 6., 15. and 20. and
xx
yy
zz
value of the pressure of water PRE1 at moment 20 with nodes NO8. The values of reference are
values of not-regression.
Values of and:
xx
yy
Moment
Reference
Aster
1st loading 3.
3.000000+05 3.000000+05
1st loading 6.
6.000000+05 6.000000+05
2nd loading 15.
2.590356+05 2.590355371917+05
2nd loading 20.
2.495777+05 2.495776491115+05
Values of:
zz
Moment
Reference
Aster
1st loading 3.
3.000000+05 3.000000+05
1st loading 6.
6.000000+05 6.000000+05
2nd loading 15.
5.560431+05 5.650429335188+05
2nd loading 20.
5.578873+05 5.578813428168+05
Values of PRE1:
Moment
Reference
Aster
2emechargement 20.
3.50422+05 3.50422350888+05
Handbook of Validation
V6.04 booklet: Nonlinear statics of the voluminal structures
HT-66/03/008/A
Code_Aster ®
Version
6.4
Titrate:
SSNV165 - Triaxial Essai not drained with law CAM_CLAY
Date:
03/06/03
Author (S):
G. DEBRUYNE, J. EL GHARIB Key
:
V6.04.165-A Page:
6/6
4
Summary of the results
tr ()
By interpreting the diagram, (P, Q), P = -
and Q = - (-) in the case of this case test, one
3
3
1
note well that the loading remains hydrostatic up to a value of 6.E5Pa. Once it
vertical displacement is imposed and varies with time, the pressures on the side faces being
maintained constant, a diverter of constraints is induced and increases with time with one
positive work hardening. When one approaches the point Q = MP, one tends towards perfect plasticity with
plastic flow without work hardening and variation of constraints (see [§6] Doc.
[R7.01.14]).
Handbook of Validation
V6.04 booklet: Nonlinear statics of the voluminal structures
HT-66/03/008/A
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