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