Érosion rosion interne interne dans les ouvrageshydrauliques ouvrageshydrauliques · 2012. 1....
TRANSCRIPT
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ÉÉRosionRosion INterneINterne dans les dans les OuvragesHydrauliquesOuvragesHydrauliques Internal Erosion in Hydraulic WorksInternal Erosion in Hydraulic Works
EssaisEssais de de laboratoirelaboratoire (CEMAGREF)
Nadia BenahmedNadia Benahmed
PROJET ANR PGCU ERINOH
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1993 Camargue dikes, France
12 breaches in December 1993 and 4 breaches in January 1994
Saint-Gilles flood, 2003
Breache of Fourques, Petit Rhône Rive Droite
The Ouches Dam, 2001 (200 years old)
- 3 total breaches- 3 partial breaches- 5 fatalities
Sinkholes
Rupture of Aramon dike, 2002
Contexte
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On sait depuis quelques années qu’il y a environ 8000 km de digues de protection contre les inondations en France :
– 8700 km* au dernier recensement
– … dont 2500 km* dans les régions Provence-Alpes-Côte d’Azur (1890 km : 1/22) et Languedoc-Roussillon (650 km : 4/22)
… mais depuis peu de temps que :
– 2700 km* de digues (existantes) de classes A et B doivent faire l’objet d’une étude de dangers d’ici le 31/12/2012
– 3200 km* de classe C d’ici le 31/12/2014
* Sources : logiciel BarDigues (R Tourment, M. Wolff – Cemagref)
Rappel
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Internal erosion : complex phenomenon which affect stability of hydraulic works (earth dams, dykes,…) Failure
ERINOH 2008 Four types of internal erosion:
• Regressive erosion • Contact erosion• Suffosion• Piping flow erosion
Ouches dam, july
2001
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Brief
review…Sherard et al. 1976:
Pinhole Test Apparatus
Lack: Qualitative test, no quantitative data!
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Other references :
Hole Erosion test (Christensen & Das, 1973)
Leakage Erosion test (Hjeldnes & Lavania, 1980)
Drill Erosion test (Lefebvre, 1986) (Canada)
Crack Erosion test (Sanchez & al., 1983; Maranha das Neves, 1987)
Surface and Internal Erosion test (Reddi, Lee & Bonala, 2000)
Constat :
Several experimental procedures
Dispersion and different interpretations of experimental results
Nonexistence of appropriate theoretical model to fit the
experimental data !!!
Brief
review…
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Pressure transducersTurbidity meter
Flowmeter
Hole
Erosion Device
(CEMAGREF)
Turbidity meter
Pressure outSample
Pressure in
Flow in
Flow out
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Experimental
results
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0:00:00 0:15:00 0:30:01 0:45:01 1:00:01 1:15:01 1:30:02 1:45:02 2:00:02
Temps (h)
Déb
it Q
(kg/
h) ;
Turb
idité
(NTU
)
0
10
20
30
40
50
60
70
80
90
100
Gra
dien
t de
pres
sion
Del
ta P
(kPa
)
Turbidité (NTU)Débit massique (kg/h)Delta P (kPa)
( )sinon
si
0er b c b ckm
τ τ τ τ⎧ − >⎪= ⎨⎪⎩
&
Loi d’érosion à seuil : Paramètres d’érosion :
• Seuil d’érosion τc• Coefficient d’érosion kd
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• Seuil d’érosion τc• Coefficient d’érosion kd
0
1
2
3
4
5
6
71 10 100 1000
Eros
ion
rate
inde
x Ie
Fell DataSample N°1
Critical shear stress τc (Pa)
Moderatly rapid
Very rapid
Moderatly slow
Very slow
Extremely slow
Extremely rapid
Wan and Fell guidelines
Experimental
results
Wan and Fell (2002, 2004)
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Experimental
resultsSlot erosion test :
Sample before erosion Sample during testing Sample after erosion
Hole erosion test :
Sample after erosionSample before erosion Sample after erosion
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Sample before erosion Sample after erosion, upstream side
Naturel soil : Silty sand (26% sand, 58% silts, 16% clay)
Sample after erosion, down stream side
Naturel soil : Sandy silt (72% sand, 23% silts, 4% clay)
Collapse of the sample during filling of the testing cell
Experimental
results
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Soil : KAOLINITE
0.001 0.01 0.1 1 10 100Dimension des particules (mm)
0
10
20
30
40
50
60
70
80
90
100
Tam
isat
(%)
KAOLIN
pH 4 to 9
Density : 2.6 g/cm3
Dry density Opt. : 1.51 t/m3
W Opt. : 23.5 %
Wl = 49 Wp = 33 Ip = 16 Grain size distribution
Experimental
study
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Effect of moisture content on τc and Ie (ρd = 1.4 t/m3 (95% OPN))
0
10
20
30
40
50
60
70
16 20 24 28 32
Moisture content W (%)
Crit
ical
she
ar s
tress
τc
(Pa)
0
1
2
3
4
5
6
16 20 24 28 32
Moisture content W (%)
Eros
ion
rate
inde
x Ie
Effect of dry density on τc and Ie (W = 23.5 %)
20
30
40
50
60
1,20 1,25 1,30 1,35 1,40 1,45 1,50
Dry density ρd (t/m3)
Crit
ical
she
ar s
tres
s τc
(Pa)
0
1
2
3
4
5
1,20 1,25 1,30 1,35 1,40 1,45 1,50
Dry density ρd (t/m3)
Eros
ion
rate
inde
x Ie
Experimental
results
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Effect of energy of compaction
3,761,75E-041,00E-012,01E-0428,511517,2Sample N° 2(1/4 Proctor)
3,951,18E-046,49E-021,36E-0465,291517,9Sample N° 1(Proctor)
IeCe(s/m)kd
(cm3/N.s)ker
(s/m)τc
(Pa)W(%)
γd(kN/m3)
3,761,75E-041,00E-012,01E-0428,511517,2Sample N° 2(1/4 Proctor)
3,951,18E-046,49E-021,36E-0465,291517,9Sample N° 1(Proctor)
IeCe(s/m)kd
(cm3/N.s)ker
(s/m)τc
(Pa)W(%)
γd(kN/m3)
Fell guidelines0
1
2
3
4
5
6
71 10 100 1000
Eros
ion
rate
inde
x Ie
Fell DataSample N°1Sample N°2
Critical shear stress τc (Pa)
Moderatly rapid
Very rapid
Moderatly slow
Very slow
Extremely slow
Extremely rapid
1/4 Proctor
Proctor
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Effect of clay content
Sample N°1
Sample N°2
Sample N°3
Sand > 50 μm (%) 44 41 33
Silt > 2 μm (%) 30 39 41
Clay < 2 μm (%) 26 20 26
γd (kN/m3) 16,7 16,7 16,7
W (%) 18 19 21
τc (Pa) 103,25 31,49 110,75
Ie 4,10 3,60 4,19
kd (cm3/N.s) 4,68E-02 1,48E-02 3,82E-01
Fell guidelines0
1
2
3
4
5
6
71 10 100 1000
Eros
ion
rate
inde
x Ie
Fell DataSample N°1Sample N°2Sample N°3
Critical shear stress τc (Pa)
Moderatly rapid
Very rapid
Moderatly slow
Very slow
Extremely slow
Extremely rapid
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Ageing effect ?
Wan et Fell guidelines0
1
2
3
4
5
6
71 10 100 1000
Eros
ion
rate
inde
x Ie
Fell Data
ReconstitutedsamplesUndisturbedsamples
Critical shear stress tc (Pa)
Moderatly rapid
Very rapid
Moderatly slow
Very slow
Extremely slow
Extremely rapid
HET tests on naturel soils
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Merci de votre attention !
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Failure of Teton Dam by piping
Failure: On 3 hours only!
Contexte
Diapositive numéro 1Diapositive numéro 2Diapositive numéro 3Diapositive numéro 4Diapositive numéro 5Diapositive numéro 6Diapositive numéro 7Diapositive numéro 8Diapositive numéro 9Diapositive numéro 10Diapositive numéro 11Diapositive numéro 12Diapositive numéro 13Diapositive numéro 14Diapositive numéro 15Diapositive numéro 16Diapositive numéro 17Diapositive numéro 18