WTNV122 - Triaxial compression test not drained with law CAM

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Titrate:

WTNV122 - Triaxial compression test not drained with law CAM_CLAY

Date:

27/09/04

Author (S):

G. DEBRUYNE, J. EL GHARIB

Key

V7.31.122-A

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1/10

Manual of Validation

V7.31 booklet: Thermo hydro-mechanical in porous environment of voluminal structures

HT-66/04/005/A

Organization (S):

EDF-R & D/AMA

Manual of Validation
V7.31 booklet: Thermo hydro-mechanical in porous environment of structures
voluminal
Document: V7.31.122

WTNV122 - Triaxial compression test 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.
Three different modelings are carried out in 3D. In each modeling, the test is carried out in
hydro-mechanical coupling and it include/understand two ways of loading:

Modeling A is characterized by:

a hydrostatic way of compression in condition drained until the pressure of consolidation,

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, and a plastic mode
contractor.

Modeling B is characterized by:

a hydrostatic way of compression in condition drained until the critical pressure, equalizes with
half of the pressure of consolidation,

Modeling C is characterized by:

a hydrostatic way of compression in condition drained until a pressure lower than
critical pressure,

a way not-drained by maintaining the pressures lateral confining on the sample and by imposing one
vertical displacement of compression which induces a plastic state of stresses triaxial dilating.

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Titrate:

WTNV122 - Triaxial compression test not drained with law CAM_CLAY

Date:

27/09/04

Author (S):

G. DEBRUYNE, J. EL GHARIB

Key

V7.31.122-A

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Problem of reference

1.1 Geometry

height: H = 1m
width: L = 1 m
thickness: E = 1 m

1.2

Properties of material

22 E

= E

Parameters specific to CAM_CLAY:

PORO

CRIT

NEAR

AP,

1 E

1.3

Boundary conditions and loadings

The first way of loading is carried out with a state of hydrostatic stresses:

. One makes a first elastic design until

(to establish an initial state

plastically acceptable). One increases then

until

sup

, the pressure of water is maintained

null

PRE

(drained condition). For the second way, one maintains the pressure

on the faces

side and one imposes then a vertical displacement imposed in compression to modelize one
triaxial compression test, calculation is now not drained, which corresponds to a hydrostatic flow no one on
all faces.
For modeling a:

ion

consolidat

sup

(final state contracting)

For modeling b:

sup

(final state criticizes with null voluminal variation)

For modeling C:

sup

(final state dilating)

1.4 Conditions

initial

The plastic condition of compatibility requires that in an initial state the hydrostatic stress be
strictly higher than zero. To initialize this stress, one chose to carry out at the beginning a calculation
purely elastic while making evolve/move pressure of 0. with 1.E5 AP. One only extracts from this calculation
the stress field at the points of gauss. This stress field resulting from the elastic design is
regarded as the initial state of the hydrostatic stress necessary to the law Cam_Clay of calculation
according to.

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WTNV122 - Triaxial compression test not drained with law CAM_CLAY

Date:

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Author (S):

G. DEBRUYNE, J. EL GHARIB

Key

V7.31.122-A

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HT-66/04/005/A

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.

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WTNV122 - Triaxial compression test not drained with law CAM_CLAY

Date:

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Author (S):

G. DEBRUYNE, J. EL GHARIB

Key

V7.31.122-A

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V7.31 booklet: Thermo hydro-mechanical in porous environment of voluminal structures

HT-66/04/005/A

3 Modeling

With

Modeling A is characterized by:

a hydrostatic way of compression in condition drained until the pressure of
consolidation,

a way not-drained by maintaining the pressures lateral confining on the sample and while imposing
a vertical displacement of compression which induces a triaxial state of stresses, and a mode
contracting plastic.

3.1

Characteristics of modeling

Modeling 3D

NO12

NO2

NO3

NO10

NO9

NO13

NO15

NO14

NO11

NO20

NO19

NO18

NO1

NO7

NO6

NO8

NO16

NO4

NO5

NO17

3.2

Characteristics of the mesh

A number of nodes:

A number of meshs:

1 of type HEXA 20

6 of type QUAD 8

The following meshs are defined:

STRAIGHT LINE

NO3 NO5 NO8 NO10 NO12 NO15 NO17 NO20

LEFT

NO1 NO4 NO6 NO9 NO11 NO13 NO16 NO18

IN FRONT OF

NO6 NO7 NO8 NO11 NO12 NO18 NO19 NO20

BEHIND

NO1 NO2 NO3 NO9 NO10 NO13 NO14 NO15

LOW

NO13 NO14 NO15 NO16 NO17 NO18 NO19 NO20

HIGH

NO1 NO2 NO3 NO4 NO5 NO6 NO7 NO8

To account for the 1/8

ème

structure, the boundary conditions in displacement imposed are:

On the LOW face: DZ = 0
On the LEFT face: DY = 0
On the face BEHIND: DX = 0

The loading is consisted of the same pressure divided into compression on the 3 meshs: `HIGH,
“RIGHT” and “IN FRONT” to simulate a hydrostatic test, and of a null water pressure to simulate
the condition of drainage (

PRE

). Then, the pressure distributed is maintained constant on

side faces “STRAIGHT LINE” and “IN FRONT OF”, a displacement DZ is imposed on the variable face “HIGH”
with time, and one changes the hydraulic loading (null flow) to simulate the condition not
drained.

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WTNV122 - Triaxial compression test not drained with law CAM_CLAY

Date:

27/09/04

Author (S):

G. DEBRUYNE, J. EL GHARIB

Key

V7.31.122-A

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HT-66/04/005/A

3.3 Functionalities

tested

Controls

DEFI_MATERIAU CAM_CLAY

STAT_NON_LINE COMP_INCR

NEWTON

RELATION= `KIT_HM'

`RELATION_KIT'=

“CAM_CLAY”

“LIQU_SATU”

“HYDR_UTIL”

STAMP = “TANGENT”

3.4

Sizes tested and results

Components

and

stress are tested at moments 3., 6., 15. and 20. and

value of the pressure of water PRE1 at moment 20 with node NO8. The values of reference are
values of not-regression.

Values of

and

Moment

Reference

Aster

loading

3. 3.000000+05

 3.000000+05

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

Moment

Reference

Aster

loading

3. 3.000000+05

 3.000000+05

loading

6. 6.000000+05

 6.000000+05

2nd loading

15. 5.650431+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

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Titrate:

WTNV122 - Triaxial compression test not drained with law CAM_CLAY

Date:

27/09/04

Author (S):

G. DEBRUYNE, J. EL GHARIB

Key

V7.31.122-A

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V7.31 booklet: Thermo hydro-mechanical in porous environment of voluminal structures

HT-66/04/005/A

4 Modeling

Modeling B is characterized by:

a hydrostatic way of compression in condition drained until the critical pressure,
equalize with half of the pressure of consolidation,

4.1

Characteristics of modeling

Idem modeling A

4.2

Characteristics of the mesh

Idem modeling A

4.3 Functionalities

tested

Idem modeling A

4.4

Sizes tested and results

Components

and

stress are tested at moments 3., 6., 15. and 20. and

value of the pressure of water PRE1 at moment 20 with node NO8. The values of reference are
values of not-regression.

Values of

and

Moment

Reference

Aster

loading

3. 2.000000+05

 2.000000+05

loading

6. 3.000000+05

 3.000000+05

2nd loading

15.

 2.100000+05

 2.099999 +05

2nd loading

20.

 2.100000+05

Values of

Moment

Reference

Aster

loading

3. 2.000000+05

 2.000000+05

loading

6. 3.000000+05

 3.000000+05

2nd loading

15. 4.800000+05

 4.799999+05

2nd loading

20. 4.800000+05

 4.800000

+05

Values of PRE1:

Moment

Reference

Aster

2emechargement

20. 9.00000+E4

9.00000+E4

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Titrate:

WTNV122 - Triaxial compression test not drained with law CAM_CLAY

Date:

27/09/04

Author (S):

G. DEBRUYNE, J. EL GHARIB

Key

V7.31.122-A

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V7.31 booklet: Thermo hydro-mechanical in porous environment of voluminal structures

HT-66/04/005/A

5 Modeling

Modeling C is characterized by:

a hydrostatic way of compression in condition drained until a pressure lower than
critical pressure,

5.1

Characteristics of modeling

Idem modeling A

5.2

Characteristics of the mesh

Idem modeling A

5.3 Functionalities

tested

Idem modeling A

5.4

Sizes tested and results

Components

and

stress are tested at moments 3., 6., 15. and 20. and

value of the pressure of water PRE1 at moment 20 with node NO8. The values of reference are
values of not-regression.

Values of

and

Moment

Reference

Aster

loading

3. 2.000000+05

 2.000000+05

loading

6. 2.200000+05

 2.200000+05

2nd loading

15.

 1.560470+05

 1.560470100963+05

2nd loading

20.

 1.815567+05

 1.815567285399+05

Values of

Moment

Reference

Aster

loading

3. 2.000000+05

 2.000000+05

loading

6. 2.200000+05

 2.200000+05

2nd loading

15. 4.156324+05

 4.156324653437+05

2nd loading

20. 4.382215+05

 4.382215080457+05

Values of PRE1:

Moment

Reference

Aster

2emechargement

20. 3.844327+E4

3.844327146008+E4

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Titrate:

WTNV122 - Triaxial compression test not drained with law CAM_CLAY

Date:

27/09/04

Author (S):

G. DEBRUYNE, J. EL GHARIB

Key

V7.31.122-A

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V7.31 booklet: Thermo hydro-mechanical in porous environment of voluminal structures

HT-66/04/005/A

Summary of the results

By interpreting the diagram, (P, Q),

()

and

)

(

for three modelings of

this case test, one notes well that in modeling A [Figure 6-a], the loading remains
hydrostatic up to a value of

6th

AP. Once vertical displacement is imposed and

vary with time, the pressures on the side faces being maintained constant, a diverter
stresses is induced and increases with time with a positive work hardening. When one
bring closer the point

, one tends towards perfect plasticity with plastic flow without

work hardening and without variation of stresses (see [§6] Doc. [R7.01.14]).

Appear 6-a: Q according to P (modeling A)

In modeling B [Figure 6-b], after a hydrostatic loading which reaches the critical pressure
with

3rd

AP, the second loading are only deviatoric with a hydrostatic pressure

maintained with

3rd

AP. When one reaches the point criticizes, one touches the critical slope, where plasticity is

perfect with plastic flow without work hardening and variation of stresses.

Q =

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WTNV122 - Triaxial compression test not drained with law CAM_CLAY

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HT-66/04/005/A

Appear 6-b: Q according to P (modeling B)

In modeling C [Figure 6-c], vertical displacement is imposed before the loading
hydrostatic reached the critical pressure. The diverter of the stresses varies with time, during
that the pressures on the side faces are maintained constant. Like the criterion of plasticity
is reached in the field of dilatancy, work hardening is negative and the diverter of the stresses
decrease with time.

Appear 6-c: Q according to P (modeling C)