c3 Farimah Masrouri - LTU

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http://www.laego.org 1/29

Farimah MASROURI Professor in Geotechnical Engineering

LAEGO : Research Center In Geomechanics & Geoenvironmental Engineering

Nancy – UniversitéFrance

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Paris Nancy ~300 km

Nancy

90 min by TGV

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LAEGO : Research Center In Geomechanics & GeoenvironmentalEngineering

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Research teams

Rock Mechanics

Transfer in Porous media

Soil Mechanics

Systems & Risks

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Hydro-mechanical, Physical & Numerical Modelingof Soil Behavior

• Soil : Saturated, Unsaturated, Swelling or Rigid, Natural or Remolded -Treated

• Coupling : Hydraulic – Mechanical - Thermal & Chemical

• Multiscale : Lab (micro- et macroscopique ), in situ

• Aging & Time effects

Geotechnical EngineeringGeoenvironmental EngineeringConstruction Safety

Applications :

Soil Mechanics

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Swelling and shrinkage of unsaturated claysSwelling and shrinkage of unsaturated clays

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• When wetted, swelling soils can apply very high uplift pressures which can damage lightly-loaded structures.

• Expansive soils pose the greatest hazard in arid regions, which are much more susceptible to damage from expansive soils, than regions that maintain moist soil conditions throughout the year.

Expansive Clayey Soils

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http://www.laego.org 8/29Photos : P. Berthelot

2007

Small building in SenegalIndividual house in Tunisia

Arid Regions Swelling

Expansive soils damage foundations by uplift as the soils swell with moisture increases

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Buildings in Dakar - Senegal



Photo : P. Berthelot2007

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Buildings in Dakar - Senegal



Photos : P. Berthelot2007

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• Insurance companies pay out millions of euros yearly, to repair homes distressed by expansive soils (4,3 billions of euros between 1989 and 2006 ))

Global warming very long drought periods (1989-92, 1996-97, 2003, 2006,…) there are significant damages to foundations of light buildings

Shrinkage of clayey soils is considered as a natural hazard

France Shrinkage

Photos : R. Fabre2007

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• Surface evaporation and tree roots Differential water content

France Shrinkage

Photos : BRGM

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Influence of several wetting-drying cycles on the hydro-mechanical behaviour of clay soils

Analysis and modelling of drought propagation in the soil

11

22

ExamplesExamples ::

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Compacted swelling soil

Chou et Mou (1973)

Swellingaccumulation

Equilibrium stage

Alonso et al. (2005)

Mixture of bentonite/sand (80/20)

Shrinkageaccumilation

Equilibrium stage

Influence of several suction cycles on theHydro-mechanical behaviour of the swelling soils

11

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Mixture of two materials: 60% of bentonite + 40% of silt.

Characterisation of the tested materials (1/2)

2.672.632.71Specific Gravity (Gs)

14 -15--Shrinkage Limit(%)

22305Plasticity Index(%)

658137Plasticity Limit (%)

8711142Liquid Limit (%)

MixtureBentoniteSiltPhysical Property


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Initial states of the samples

12.7Dry unit weight (kN/m3)

1000

20 ± 2

37

70

10

15 ± 0.3

Loose samples

Height (mm)

Diameter (mm)

Parameters

Suction (MPa)

Compaction pressure (kPa)

Degree of saturation (%)

Water content (%)

Characterisation of the tested materials (2/2)

3000

20 ± 2

15.5

37

70

10

15 ± 0.3

Dense samples

11Influence of several suction cycles on theHydro-mechanical behaviour of the swelling soils

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Vertical net stress (kPa)

Suc

tion

(MP

a)

Followed stress paths

B8

A20

10

C

15

D

30

E

60F G H

0.01

3 cycles

11Influence of several suction cycles on theHydro-mechanical behaviour of the swelling soils

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11

Kassif & Ben Shalom (1971), Delage et al. (1992)

Suction Controlled Osmotic oedometer (0 to 8 MPa)


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0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0.01 0.1 1 10 100

Suction (MPa)

Void

ratio

(-)

Applied vertical stress=30 kPa, initial density=1.27 Mg/m3

Applied vertical stress=30 kPa, initial dry density=1.57 Mg/m3

L2 (initial density=1.27 Mg/m3)D2 (initial density=1.55 Mg/m3)

Applied vertical stress=30 kPa

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0.01 0.1 1 10 100

Suction (MPa)

Void

ratio

(-)

Applied vertical stress=15 kPa, initial density=1.27 Mg/m3

Applied vertical stress=15 kPa, initial dry density=1.57 Mg/m3L1 (initial density=1.27 Mg/m3)D1 (initial density=1.55 Mg/m3)

Applied vertical stress=15 kPa

15 kPa

Swelling accumulationDense sample

Loose sample

Shrinkage accumulation

30 kPaLoose sample


Dense sample Swelling accumulation

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0.01 0.1 1 10 100

Suction (MPa)

Void

ratio

(-)

Applied vertical stress=60 kPa, initial density=1.27 Mg/m3Applied vertical stress=60 kPa, initial dry density=1.57 Mg/m3

L3 (initial density=1.27 Mg/m3)D3 (initial density=1.55 Mg/m3)

Applied vertical stress=60 kPaLoose sample


Dense sample Swelling accumulation

Void ratio - Suction

60 kPa

11

LAEGO LAEGO –– H. H. NowamoozNowamooz


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1. For the swelling soils submitted to several wetting and drying cycles, the factors influencing the volumetric deformation are :• the preconsolidation stress ;• the initial density and the water content.

2. After several suction cycles, an elastic state can be reached;

3. Intensity of the applied charge influences the necessary number of suction cycles to reach the equilibrium point.

Remarks 11

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– Fine graded soils Cam Clay

– Unsaturated soils BBM (Barcelona Basic Model)

– Swelling soils BExM (B. Expansive Model)Gens & Alonso (1992);

Alonso et al. (1999, 2005) : BExM

Hydro-mechanical behaviour of expansive soils22

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0,25em0,011κm

Micro / macro-structural coupling functions

Microstructural soil parameters

0,844 MPa30 MPa14 MPa

0,091,24

p0*

s0shkM

0,020,3150,2777

8,054×10-3 MPa-1

0,0150,609 MPa

κλ(0)rβκspc

f = 1×10-3 + 2×10-2 (1 - p* /p0)0,1fI = 0,5 + 9,9 (p* /p0 )1

Macro-structure soil parameters

0.25em0.011κm

0.844 MPa30 MPa14 MPa

0.091.24

p0*

s0shkM

0.020.3150.2777

8.054×10-3 MPa-1

0.0150.609 MPa

κλ(0)rβκspc

fD= 1×10-3 + 2×10-2 (1 - p* /p0)0,1fI = 0.5 + 9.9 (p* /p0 )1

Soil parameters (BExM)

Porosity n0= 0.385 Density ρs = 2.7 Mg/m3 Permeability k s = 1.66 10-6 m/s

Van Genuchten parameters : α = 27 MPa-1 ; m = 0.316 ; Sres = 0.2338

Hydro-mechanical behaviour of the swelling soilsunder shallow foundations

M. Mrad - H. Nowamooz - Laego

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22

– Objectives• Effect of wetting /drying (rain/drought) on the settlements of a

shallow foundation• Effect of a geo-membrane layer

Swelling soil

Rigid soil



backfill

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22

Propagation of Sr Without geo-membrane

Propagation of Sr With geo-membrane

Swelling soil

Rigid soil Soil deformations



Sr Propagation and soil strains

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Application to mine tailings :

Swelling pressure of treated tailingsHydraulic conductivity in Mine waste disposals…

Hydro-mechanical behaviour of the swelling soils

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Some of our recent papers in this field NOWAMOOZ H. & MASROURI F. “Relationships between soil fabric and suction cycles in compacted swelling soils“.International Journal of Engineering Geology – 2010 - 114 (3-4), pp. 444-455

NOWAMOOZ H. & MASROURI F. “Volumetric strains due to changes in suction or stress of an expansive bentonite/silt mixture treated with lime“. Comptes Rendus – Mecanique – 2010 – 338 (4), pp. 230-240.

NOWAMOOZ H. & MASROURI F. “Density-dependent hydromechanical behaviour of a compacted expansive soil”. International Journal of Engineering Geology. 2009. 106 (3-4), pp. 105-115

NOWAMOOZ H., MRAD M., ABDALLAH A, & MASROURI F. “Experimental and numerical studies of the hydromechanical behaviour of a natural unsaturated swelling soil”. Canadian Geotechnical Journal. 2009. 46 (4), pp. 393-410

NOWAMOOZ H. & MASROURI F. “Hydromechanical behaviour of an expansive bentonite/silt mixture in cyclic suction-controlled drying and wetting tests“. International Journal of Engineering Geology. 2008. 101 (3-4), pp. 154-164

MASROURI F., BICALHO K. & KAWAI K. “Laboratory hydraulic testing in unsaturated soils“. Geotechnical and Geological Engineering. 2008. Vol 26, 691-704.

DEVINEAU K., BIHANNIC I., MICHOT L., VILLIERAS F., MASROURI F., CUISINIER O., FRAGNETO G. & MICHAU N. "In situ neutron diffraction analysis of the influence of geometric confinement on crystalline swelling of montmorillonite". Applied Clay Science. Volume 31, Issues 1-2. 2006. 76-84. (ISSN : 0169-1317)

CUISINIER O. & MASROURI F. "Influence of complex hydromechanical loadings on the behaviour of a compacted expansive soil". Canadian Geotechnical Journal. Vol. 42. n° 3. 2005. 731-741. (ISSN 1208-6010)

CUISINIER O. & MASROURI F. "Hydromechanical behaviour of a compacted swelling soil over a wide suction range". International Journal of Engineering Geology. 2005. Vol. 81. n° 3 204-212. (ISSN : 0013-7952)

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Documents

c3 Farimah Masrouri - LTU