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Investigation of soil-atmosphereInteraction
Ecole des Ponts ParisTech
OUTLINE
• Laboratoire Navier/Géotechnique (CERMES)
• Environmental chamber• Field monitoring – Railway• Field monitoring – Embankment• Numerical simulation
Laboratoire Navier/Géotechnique(CERMES)
http://navier.enpc.fr/L-equipe
– 11 permanent researchers
– Staff of 5 technical + 2 administrative people
– ~ 20 PhDs (Brazil, China, Iran, Vietnam, Algeria, Cameroun, Iraq, Lebanon, France)
– ~ 5 post-doc fellows
SOILS and ROCKS
Soil-structure interactions
APPLICATIONS
RESEARCH
Sands, coarse soils, loess, clays, claystones, compacted soils, chalks, sandstones, cement…
THM couplings
Behaviour of soils et rocks
TOPICS
ANR (French Research Agency), EU, ANDRA, BRGM, CETU, EDF, FFB, EURIDICE (Belgium), NAGRA (Switzerland), IFREMER, IFPEN, INERIS, IREX, MAIF, SNCF, TOTAL
Geotechnical structuresGeomechanics and energyNatural hazards
Civil engineering Radioactive wastes Draught Offshore CO2 Tunnels
&
Experimental investigation using an environmental chamber
Air collector
Infraredthermometer
Air distributor
Set-up for soil drying
1
2
3
4
56
7
8
Surface du solCompressed air
Air speed
Heating tube
Measures RH & T
Air distributor
Air collector + Measures RH & T
Infrared thermometer
Camera
Soil surface
Probes used
10 MPa 1 MPa
ThetaProbe LVDT Thermistance
HygrometerElcowa Psychrometer ENPC HC tensiometer
100 10 1Succion totale (MPa)
10-14
10-13
10-12
10-11
Con
duct
ivité
hyd
raul
ique
(m
/s)
Total suction (MPa)Hyd
raul
icco
nduc
tivity
(m/s
)
1
10
100
1000
10000
100000
1000000
0 10 20 30 40 50 60
Volumetric water content (%)
Suc
tion
(kP
a)
Volumetric water content (%)
Suc
tion
(kP
a)
Hydraulicconductivity
Water retentioncurve
During wetting
During drying
0
20
40
60
Rel
ativ
e hu
mid
ity
(%) Outlet
ChamberInlet
24
32
40
Air
tem
pera
ture
(°C)
OutletChamberInlet
1.21.31.41.51.61.7
Act
ual e
vapo
ratio
n (m
m/d
ay)
0 10 20 30Elapsed time (day)
0
20
40
Cum
ulat
edev
apor
atio
n (m
m)
60
80
100
Air
rate
(L
/min
)
(a)
Imposed condition (b)
Imposed condition
Imposed condition
(c)
1618202224
Soi
l tem
pera
true
(°C
)
0 mm50 mm250 mm> 250 mm (d)
(e)
(f)
Evaporation test results - Ctd
Scale: 1000 mm x 800 mm
total
cracksCS S
SR =
i ip
ii
n LL
n=∑
(b)
(c)
20
40
60
Vol
umet
ricw
ater
con
tent
(%)
50 mm250 mm450 mm650 mm850 mm
1
10
100
1000
10000
Soi
l suc
tion
(kP
a)
TS_195 mmPS_150 mmPS_50 mm
010203040
Cra
ck s
urfa
cera
tio (
%)
0 5 10 15 20 25 30Elapsed time (day)
10
20
30
Wei
ghed
cra
ckw
idth
(m
m) (d)
(a)
Field monitoring - Railway
Moulin Blanc site, PK 230+000 Douai – Valenciennes line (262 000)
V1V2
Valenciennes
Douai
� Criteria of site sélection� Cutting area : without drainage
� Geotechnical characteristics: sol support type A2
� Line groupe: UIC < 6
Instrumentation
Zone AZone B
Zone C
Piézomètre
Station météo et centrale d’acquisition
View of the instrumented siteInstrumentation layout
ST4
ST5ST3
ST2
ST1
ST6
ST7
ST8
0,0 m
- 0,4 m- 0,5 m
- 10,0 m
Ballast
CI
+ 0,5 m
SECTION TRANSVERSALE
Sol support
V1 DL2
SMCaténaire
Pi
- 0,3 m- 0,2 m
Capteur de température (1)T9
Pi
STi
Piézomètre (2)
Capteurs de succion - température (8)
Légende
Station météo (1 Plu, 1 Ané, 1 Thermo, 1 sonde de RAY et 1 sonde d 'HR)
Centrale d'acquisition DL2e (1)
SM
DL2
- 0,3 m
- 0,5 m
T9
Results
� The température under ballast is always positive � The fonction of protection against frost of sub-grade is ensured
25-A
ug-0
924
-Sep
-0924
-Oct-
0923
-Nov
-09
23-D
ec-0
922
-Jan-
1021
-Feb-
1023
-Mar-
1022
-Apr
-1022
-May
-1021
-Jun
-10
21-Ju
l-10
Temps
-10
0
10
20
30
40
Tem
pér
atu
re (
°C)
Zone CT 8_z = -0,5 m T 7_z = -0,3 m
Zone AT 1_z = -0,5 m T 3_z = -0,2 m
Zone BT 4_z = -0,5 mT 5_z = -0,3 mT 6_z = -0,2 m
Thermo_z = 2,0 m T 9_z = 0,0 m (surface)
0
6
12
18
24
Tem
péra
ture
(°C
)
Results
� The suctions in the soil under ballast are low
� The increase of suction in the soil under track is due to evaporation
25-A
ug-0
924
-Sep
-09
24-O
ct-09
23-N
ov-0
923
-Dec
-0922
-Jan
-1021
-Feb-
1023
-Mar
-10
22-A
pr-1
022
-May
-10
21-Ju
n-10
21-J
ul-10
Temps
0
5
10
15
20
25
Préc
ipita
tion
(mm
)
0
2
4
6
8
10
Su
ccio
n (k
Pa)
Zone ASIS 1_z = -0,5 m SIS 2_z = -0,3 mSIS 3_z = -0,2 m
Zone BSIS 4_z = -0,5 m SIS 5_z = -0,3 m SIS 6_z = -0,2 m
Zone CSIS 7_z = -0,3 m SIS 8_z = -0,5 m
0
1
2
3
4
5
ET 0
(m
m/jo
ur)
Penman-Monteith
25-A
ug-0
924
-Sep
-0924
-Oct-
0923
-Nov
-09
23-D
ec-0
922
-Jan
-10
21-F
eb-1
023
-Mar
-10
22-A
pr-1
022
-May
-10
21-J
un-1
021
-Jul-
10
Temps
20
40
60
80
100
Hum
idité
rel
ativ
e (%
)
0
4
8
12
Vite
sse
du
ven
t (m
/s) 0
0.4
0.8
1.2
Ra
yon
nem
en
t (kW
/m2 )
-10
0
10
20
30
40
Tem
pér
atu
re d
'air
(°C
)
Embankment in Héricourt
Silt side Clay side
Air
Air - ctd
Soil – embankment slope
(a)
(b)
(c)
Effect of freezing/thawing
• Mechanisms of swelling due to freezing and damage due to freezing/thawing cycles
• Impact on earthworks made up of lime treated soils
Numerical investigation
stockθ − THM code by Gatmiri et al. (1999), Gatmiri and Arson (2008)
( )ZDDTDq wTww ∇−∇−∇−= θρ θ
−−=
T
r
b
ru
rurwzw S
SSKD
µµ
10
0 010 ewz wK Kα=
∇+
∇−∇
∂∂
−= ZP
KTT
PKq
g
g
g
g
g
g
gg γγρ
( )( )d
r
g
g
g Seg
cK −= 1µ
ρ
Water flow
Air flow
Consitutive model - State surface
( ) ( )
01
0
11
1
exp[ ]exp1
m
g g g we e
atm e atme
b
ee
p p p pa b
p pc T T
K m
σ σσ
−
+= − − − −
+ − − −
( ) ( )( ) ( )( )01- - 1-exp - exp -r s s g s g w sS a b p c p p d T Tσ = +
Gatmiri and Delage (2007)
Basic equations about infiltration and evaporation
nfoffTe IREIP +++= int
Tn EHGR λ++=
ah
aspa r
TTcH
−= ρ
( )v
vavs
a
aT r
PP
pE
−=
λερλ
( ) 2/)()( minmaxmaxmin hTPhTPP vsatvsatva +=
( ) 17.270.6108exp
237.3vsat
TP T
T = +
Inf determined if ET known
Ts and Pvs are soil property dependent, and should be properly determined
Remark:
Ts and Pvs are not included in the equations for potential evaporation determination
Mormoirons site
- Clay of green colour till 10 m depth
- Meteorological data fromCarpentras station, 10 km from the Mormoirons site
- 17-month period from01/01/2007 to 25/05/2008
Soil settlement – comparison between calculation and measurement
Exchanges within TU1202
• Data available- Environmental chamber (Romainville clay,
sand, Héricourt clay, lime treated Héricourt clay
- Freezing swelling (lime treated soils)- Mont Blanc site- Possibly Mormoirons site, Héricourt site- Laboratory elementary tests