Internal stability of granular materials in triaxial tests · Internal stability of granular...

Internal stability of granular

materials in triaxial tests

Livah ANDRIANATREHINA (1), Hanène SOULI (1),

Jean-Jacques FRY (2), QuocTuan PHAN (3), Jean-Marie FLEUREAU (3)

(1)-Laboratoire de Tribologie et Dynamique des Systèmes CNRS/UMR 5513, ENISE 58 Rue Jean Parot, 42023 Saint Etienne cedex 02

(2)- Électricité de France, Centre Ingénierie Hydraulique ,

73073 Le Bourget du Lac cedex

(3) Laboratoire de Mécanique (Sols, Structures & matériaux) CNRS/UMR 8579 ,ECP

Grande voie des vignes 92290 Châtenay-Malabry cedex

6th International Conference on Scour and Erosion, Paris Aug. 27-31, 2012

2

CONTENTS

I. Introduction;

II. Presentation of materials;

III. Experimental procedure of the tests;

IV. Internal stability;

V. Results;

VI. Conclusions.


3

CONTENTS

I. Introduction;




V. Results;

VI. Conclusions.


4

I. INTRODUCTION

OVERVIEW OF THE MIGRATION OF FINES:

Migration of

fines

Heterogeneity

of the material

in dam

Differential

settlement Loss of

performance

Phenomenon of

piping

Instability of

the dam


5

CONTENTS

I. Introduction;



IV. Internal stability

V. Results;

VI. Conclusions.


6

II. PRESENTATION OF THE MATERIALS

0

20

40

60

80

100

100 1000 10000 100000

C5

C10

C20

C30

C7

Pa

ssin

g (

%)

Grain diameter (µm)

Continuous grain size distribution

0

20

40

60

80

100

100 1000 10000 100000

D5

D10

D20

D30

Pa

ssin

g (

%)

Grain diameter (µm)

Discontinuous grain size distribution

Name < 0.315

[mm] CU

C5

continuous

5 13,7

C7 7 9,4

C10 10 20,7

C20 20 19,1

C30 30 8,5

D5

discontinuous

5 2,6

D10 10 2,9 - 29

D20 20 35,7

D30 30 35,5

All materials have

Cu =d60/d10>2, then : widely graded

Fine = Φ < 0.315 mm

Cx or Dx = material having respectively

continuous or discontinuous grain size

distribution, containing x% of fines


7

CONTENTS

I. Introduction;



IV. Internal stability

V. Results;

VI. Conclusions.


8

III. EXPERIMENTAL PROCEDURE OF THE TESTS

Equipment:

Triaxial cell;

the loading frame Pressure controller

Saturating;

B check = Δu/Δσ3;

Consolidating;

Shearing.

The triaxial test is consists in:

2 Relative densities:Dr = 50, 90%;

3 effective confining stresses:

σ’3 = 50, 100, 200kPa;

Initial water content: 0 to 4 %.


9

CONTENTS

I. Introduction;




V. Results;

VI. Conclusions.


10

IV. INTERNAL STABILITY OF THE MATERIAL

1)Terzaghi (1953);

2)Kezdi (1979);

3)Kenney and Lau (1985; 1986);

4)Burenkova (1993).

CRITERIA TO EVALUATE INTERNAL STABILITY


11

IV. INTERNAL STABILITY OF THE MATERIAL

Kenney and Lau (1985; 1986)+ Kezdi (1979):

C5 C7 C10 C20 C30 D5 D10 D20 D30

Kenney & Lau (1985,

1986) S S S S S U U U U

Continuous grain size distribution Discontinuous grain size distribution

0

20

40

60

80

100

0 20 40 60 80 100

C5

C10

C20

C30

C7

H=F

H:

mass f

racti

on

betw

een

D a

nd

4D

F: mass fraction smaller than

Unstable

K&L

Stable

K&L

0

20

40

60

80

100

0 20 40 60 80 100

H:

mass f

racti

on

betw

een

D a

nd

4D

D5

D10

D20

D30

H=F

F: mas fraction smaller than

Stable

K&L

Unstable

K&L

Narrowly Graded Narrowly Graded Widely Graded Widely Graded

Kenney & Lau

(1985,1986) + Kezdi

(1979)

U U U S S U U U U

Stable Kezdi

Unstable Kezdi

Stable Kezdi

Unstable Kezdi


12

CONTENTS

I. Introduction;




V. Results;

VI. Conclusions.


13

V. RESULTS

DIRECT MEASUREMENT OF THE STABILITY OF THE STUDIED SOILS

AFTER TRIAXIAL TESTS

0

20

40

60

80

100

0.1 1 10 100

initial

triax_upper

triax_medium

triax_lower

Pa

ssin

g (

%)

Grain diameter (mm)

D20

Size analysis tests


ΔPmoy

- ΔP≤10%: Stable;

- ΔP>10%: Unstable.

14

CONTENTS

I. Introduction;




V. Results;

VI. Conclusions.


15

VI. CONCLUSION

C5 C7 C10 C20 C30 D5 D10 D20 D30

Direct measurement U U S S S U U U S

Summary table

analysis of internal stability of soils must take into account several parameters.

None of the criteria gives a correct answer for all the soils (this can be caused

by differences in test conditions); In the present test, the combination of Kenney & Lau (1985, 1986) and Kezdi (1979)

gives the best assessment of the internal stability of soils;

Kenney & Lau (1985,

1986) S S S S S U U U U

Kenney & Lau

(1985,1986) + Kezdi (1979) U U U S S U U U U

Terzaghi, USACE (1953) S LS٭ S S S U U U U

Burenkova (1993) LS٭ U LS٭ S U LS٭ LS٭ U U

Limite Stable٭


16

Thank you for your attention!


Internal stability of granular materials in triaxial tests · Internal stability of granular...

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